PublicArchive/sqlalchemy
2
0
Fork 0
mirror of https://github.com/sqlalchemy/sqlalchemy.git synced 2026-06-05 07:17:06 -04:00
Code Issues Packages Projects Releases Wiki Activity
Files
52d5151aa454fa4a8470849dddb0e49df707f145
sqlalchemy/lib/sqlalchemy/sql/expression.py
T
Mike Bayer 19fcf37483 - fixed expression translation of text() clauses; this repairs various 
ORM scenarios where literal text is used for SQL expressions
2007-10-28 18:25:37 +00:00

3470 lines
117 KiB
Python
Raw Blame History

# sql.py
# Copyright (C) 2005, 2006, 2007 Michael Bayer mike_mp@zzzcomputing.com
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Defines the base components of SQL expression trees.
All components are derived from a common base class
[sqlalchemy.sql.expression#ClauseElement]. Common behaviors are organized
based on class hierarchies, in some cases via mixins.
All object construction from this package occurs via functions which
in some cases will construct composite ``ClauseElement`` structures
together, and in other cases simply return a single ``ClauseElement``
constructed directly. The function interface affords a more "DSL-ish"
feel to constructing SQL expressions and also allows future class
reorganizations.
Even though classes are not constructed directly from the outside,
most classes which have additional public methods are considered to be
public (i.e. have no leading underscore). Other classes which are
"semi-public" are marked with a single leading underscore; these
classes usually have few or no public methods and are less guaranteed
to stay the same in future releases.
"""
import re
from sqlalchemy import util, exceptions
from sqlalchemy.sql import operators, visitors
from sqlalchemy import types as sqltypes
__all__ = [
'Alias', 'ClauseElement',
'ColumnCollection', 'ColumnElement',
'CompoundSelect', 'Delete', 'FromClause', 'Insert', 'Join',
'Select', 'Selectable', 'TableClause', 'Update', 'alias', 'and_', 'asc',
'between', 'bindparam', 'case', 'cast', 'column', 'delete',
'desc', 'distinct', 'except_', 'except_all', 'exists', 'extract', 'func',
'modifier',
'insert', 'intersect', 'intersect_all', 'join', 'literal',
'literal_column', 'not_', 'null', 'or_', 'outparam', 'outerjoin', 'select',
'subquery', 'table', 'text', 'union', 'union_all', 'update', ]
BIND_PARAMS = re.compile(r'(?<![:\w\x5c]):(\w+)(?!:)', re.UNICODE)
def desc(column):
"""Return a descending ``ORDER BY`` clause element.
e.g.::
order_by = [desc(table1.mycol)]
"""
return _UnaryExpression(column, modifier=operators.desc_op)
def asc(column):
"""Return an ascending ``ORDER BY`` clause element.
e.g.::
order_by = [asc(table1.mycol)]
"""
return _UnaryExpression(column, modifier=operators.asc_op)
def outerjoin(left, right, onclause=None, **kwargs):
"""Return an ``OUTER JOIN`` clause element.
The returned object is an instance of [sqlalchemy.sql.expression#Join].
Similar functionality is also available via the ``outerjoin()``
method on any [sqlalchemy.sql.expression#FromClause].
left
The left side of the join.
right
The right side of the join.
onclause
Optional criterion for the ``ON`` clause, is derived from
foreign key relationships established between left and right
otherwise.
To chain joins together, use the ``join()`` or ``outerjoin()``
methods on the resulting ``Join`` object.
"""
return Join(left, right, onclause, isouter = True, **kwargs)
def join(left, right, onclause=None, **kwargs):
"""Return a ``JOIN`` clause element (regular inner join).
The returned object is an instance of [sqlalchemy.sql.expression#Join].
Similar functionality is also available via the ``join()`` method
on any [sqlalchemy.sql.expression#FromClause].
left
The left side of the join.
right
The right side of the join.
onclause
Optional criterion for the ``ON`` clause, is derived from
foreign key relationships established between left and right
otherwise.
To chain joins together, use the ``join()`` or ``outerjoin()``
methods on the resulting ``Join`` object.
"""
return Join(left, right, onclause, **kwargs)
def select(columns=None, whereclause=None, from_obj=[], **kwargs):
"""Returns a ``SELECT`` clause element.
Similar functionality is also available via the ``select()``
method on any [sqlalchemy.sql.expression#FromClause].
The returned object is an instance of [sqlalchemy.sql.expression#Select].
All arguments which accept ``ClauseElement`` arguments also accept
string arguments, which will be converted as appropriate into
either ``text()`` or ``literal_column()`` constructs.
columns
A list of ``ClauseElement`` objects, typically ``ColumnElement``
objects or subclasses, which will form the columns clause of the
resulting statement. For all members which are instances of
``Selectable``, the individual ``ColumnElement`` members of the
``Selectable`` will be added individually to the columns clause.
For example, specifying a ``Table`` instance will result in all
the contained ``Column`` objects within to be added to the
columns clause.
This argument is not present on the form of ``select()``
available on ``Table``.
whereclause
A ``ClauseElement`` expression which will be used to form the
``WHERE`` clause.
from_obj
A list of ``ClauseElement`` objects which will be added to the
``FROM`` clause of the resulting statement. Note that "from"
objects are automatically located within the columns and
whereclause ClauseElements. Use this parameter to explicitly
specify "from" objects which are not automatically locatable.
This could include ``Table`` objects that aren't otherwise
present, or ``Join`` objects whose presence will supercede that
of the ``Table`` objects already located in the other clauses.
\**kwargs
Additional parameters include:
prefixes
a list of strings or ``ClauseElement`` objects to include
directly after the SELECT keyword in the generated statement,
for dialect-specific query features.
distinct=False
when ``True``, applies a ``DISTINCT`` qualifier to the columns
clause of the resulting statement.
use_labels=False
when ``True``, the statement will be generated using labels
for each column in the columns clause, which qualify each
column with its parent table's (or aliases) name so that name
conflicts between columns in different tables don't occur.
The format of the label is <tablename>_<column>. The "c"
collection of the resulting ``Select`` object will use these
names as well for targeting column members.
for_update=False
when ``True``, applies ``FOR UPDATE`` to the end of the
resulting statement. Certain database dialects also support
alternate values for this parameter, for example mysql
supports "read" which translates to ``LOCK IN SHARE MODE``,
and oracle supports "nowait" which translates to ``FOR UPDATE
NOWAIT``.
correlate=True
indicates that this ``Select`` object should have its
contained ``FromClause`` elements "correlated" to an enclosing
``Select`` object. This means that any ``ClauseElement``
instance within the "froms" collection of this ``Select``
which is also present in the "froms" collection of an
enclosing select will not be rendered in the ``FROM`` clause
of this select statement.
group_by
a list of ``ClauseElement`` objects which will comprise the
``GROUP BY`` clause of the resulting select.
having
a ``ClauseElement`` that will comprise the ``HAVING`` clause
of the resulting select when ``GROUP BY`` is used.
order_by
a scalar or list of ``ClauseElement`` objects which will
comprise the ``ORDER BY`` clause of the resulting select.
limit=None
a numerical value which usually compiles to a ``LIMIT``
expression in the resulting select. Databases that don't
support ``LIMIT`` will attempt to provide similar
functionality.
offset=None
a numeric value which usually compiles to an ``OFFSET``
expression in the resulting select. Databases that don't
support ``OFFSET`` will attempt to provide similar
functionality.
bind=None
an ``Engine`` or ``Connection`` instance to which the
resulting ``Select ` object will be bound. The ``Select``
object will otherwise automatically bind to whatever
``Connectable`` instances can be located within its contained
``ClauseElement`` members.
scalar=False
deprecated. Use select(...).as_scalar() to create a "scalar
column" proxy for an existing Select object.
"""
if 'scalar' in kwargs:
util.warn_deprecated('scalar option is deprecated; see docs for details')
scalar = kwargs.pop('scalar', False)
s = Select(columns, whereclause=whereclause, from_obj=from_obj, **kwargs)
if scalar:
return s.as_scalar()
else:
return s
def subquery(alias, *args, **kwargs):
"""Return an [sqlalchemy.sql.expression#Alias] object derived from a [sqlalchemy.sql.expression#Select].
name
alias name
\*args, \**kwargs
all other arguments are delivered to the [sqlalchemy.sql.expression#select()]
function.
"""
return Select(*args, **kwargs).alias(alias)
def insert(table, values=None, inline=False, **kwargs):
"""Return an [sqlalchemy.sql.expression#Insert] clause element.
Similar functionality is available via the ``insert()`` method on
[sqlalchemy.schema#Table].
table
The table to be inserted into.
values
A dictionary which specifies the column specifications of the
``INSERT``, and is optional. If left as None, the column
specifications are determined from the bind parameters used
during the compile phase of the ``INSERT`` statement. If the
bind parameters also are None during the compile phase, then the
column specifications will be generated from the full list of
table columns.
inline
if True, SQL defaults will be compiled 'inline' into the statement
and not pre-executed.
If both `values` and compile-time bind parameters are present, the
compile-time bind parameters override the information specified
within `values` on a per-key basis.
The keys within `values` can be either ``Column`` objects or their
string identifiers. Each key may reference one of:
* a literal data value (i.e. string, number, etc.);
* a Column object;
* a SELECT statement.
If a ``SELECT`` statement is specified which references this
``INSERT`` statement's table, the statement will be correlated
against the ``INSERT`` statement.
"""
return Insert(table, values, inline=inline, **kwargs)
def update(table, whereclause=None, values=None, inline=False, **kwargs):
"""Return an [sqlalchemy.sql.expression#Update] clause element.
Similar functionality is available via the ``update()`` method on
[sqlalchemy.schema#Table].
table
The table to be updated.
whereclause
A ``ClauseElement`` describing the ``WHERE`` condition of the
``UPDATE`` statement.
values
A dictionary which specifies the ``SET`` conditions of the
``UPDATE``, and is optional. If left as None, the ``SET``
conditions are determined from the bind parameters used during
the compile phase of the ``UPDATE`` statement. If the bind
parameters also are None during the compile phase, then the
``SET`` conditions will be generated from the full list of table
columns.
inline
if True, SQL defaults will be compiled 'inline' into the statement
and not pre-executed.
If both `values` and compile-time bind parameters are present, the
compile-time bind parameters override the information specified
within `values` on a per-key basis.
The keys within `values` can be either ``Column`` objects or their
string identifiers. Each key may reference one of:
* a literal data value (i.e. string, number, etc.);
* a Column object;
* a SELECT statement.
If a ``SELECT`` statement is specified which references this
``UPDATE`` statement's table, the statement will be correlated
against the ``UPDATE`` statement.
"""
return Update(table, whereclause=whereclause, values=values, inline=inline, **kwargs)
def delete(table, whereclause = None, **kwargs):
"""Return a [sqlalchemy.sql.expression#Delete] clause element.
Similar functionality is available via the ``delete()`` method on
[sqlalchemy.schema#Table].
table
The table to be updated.
whereclause
A ``ClauseElement`` describing the ``WHERE`` condition of the
``UPDATE`` statement.
"""
return Delete(table, whereclause, **kwargs)
def and_(*clauses):
"""Join a list of clauses together using the ``AND`` operator.
The ``&`` operator is also overloaded on all
[sqlalchemy.sql.expression#_CompareMixin] subclasses to produce the same
result.
"""
if len(clauses) == 1:
return clauses[0]
return ClauseList(operator=operators.and_, *clauses)
def or_(*clauses):
"""Join a list of clauses together using the ``OR`` operator.
The ``|`` operator is also overloaded on all
[sqlalchemy.sql.expression#_CompareMixin] subclasses to produce the same
result.
"""
if len(clauses) == 1:
return clauses[0]
return ClauseList(operator=operators.or_, *clauses)
def not_(clause):
"""Return a negation of the given clause, i.e. ``NOT(clause)``.
The ``~`` operator is also overloaded on all
[sqlalchemy.sql.expression#_CompareMixin] subclasses to produce the same
result.
"""
return operators.inv(clause)
def distinct(expr):
"""Return a ``DISTINCT`` clause."""
return _UnaryExpression(expr, operator=operators.distinct_op)
def between(ctest, cleft, cright):
"""Return a ``BETWEEN`` predicate clause.
Equivalent of SQL ``clausetest BETWEEN clauseleft AND clauseright``.
The ``between()`` method on all [sqlalchemy.sql.expression#_CompareMixin] subclasses
provides similar functionality.
"""
ctest = _literal_as_binds(ctest)
return _BinaryExpression(ctest, ClauseList(_literal_as_binds(cleft, type_=ctest.type), _literal_as_binds(cright, type_=ctest.type), operator=operators.and_, group=False), operators.between_op)
def case(whens, value=None, else_=None):
"""Produce a ``CASE`` statement.
whens
A sequence of pairs to be translated into "when / then" clauses.
value
Optional for simple case statements.
else\_
Optional as well, for case defaults.
"""
whenlist = [ClauseList('WHEN', c, 'THEN', r, operator=None)
for (c,r) in whens]
if not else_ is None:
whenlist.append(ClauseList('ELSE', else_, operator=None))
if whenlist:
type = list(whenlist[-1])[-1].type
else:
type = None
cc = _CalculatedClause(None, 'CASE', value, type_=type, operator=None, group_contents=False, *whenlist + ['END'])
return cc
def cast(clause, totype, **kwargs):
"""Return a ``CAST`` function.
Equivalent of SQL ``CAST(clause AS totype)``.
Use with a [sqlalchemy.types#TypeEngine] subclass, i.e::
cast(table.c.unit_price * table.c.qty, Numeric(10,4))
or::
cast(table.c.timestamp, DATE)
"""
return _Cast(clause, totype, **kwargs)
def extract(field, expr):
"""Return the clause ``extract(field FROM expr)``."""
expr = _BinaryExpression(text(field), expr, operators.from_)
return func.extract(expr)
def exists(*args, **kwargs):
"""Return an ``EXISTS`` clause as applied to a [sqlalchemy.sql.expression#Select] object.
The resulting [sqlalchemy.sql.expression#_Exists] object can be executed by
itself or used as a subquery within an enclosing select.
\*args, \**kwargs
all arguments are sent directly to the [sqlalchemy.sql.expression#select()]
function to produce a ``SELECT`` statement.
"""
return _Exists(*args, **kwargs)
def union(*selects, **kwargs):
"""Return a ``UNION`` of multiple selectables.
The returned object is an instance of [sqlalchemy.sql.expression#CompoundSelect].
A similar ``union()`` method is available on all
[sqlalchemy.sql.expression#FromClause] subclasses.
\*selects
a list of [sqlalchemy.sql.expression#Select] instances.
\**kwargs
available keyword arguments are the same as those of
[sqlalchemy.sql.expression#select()].
"""
return _compound_select('UNION', *selects, **kwargs)
def union_all(*selects, **kwargs):
"""Return a ``UNION ALL`` of multiple selectables.
The returned object is an instance of [sqlalchemy.sql.expression#CompoundSelect].
A similar ``union_all()`` method is available on all
[sqlalchemy.sql.expression#FromClause] subclasses.
\*selects
a list of [sqlalchemy.sql.expression#Select] instances.
\**kwargs
available keyword arguments are the same as those of
[sqlalchemy.sql.expression#select()].
"""
return _compound_select('UNION ALL', *selects, **kwargs)
def except_(*selects, **kwargs):
"""Return an ``EXCEPT`` of multiple selectables.
The returned object is an instance of [sqlalchemy.sql.expression#CompoundSelect].
\*selects
a list of [sqlalchemy.sql.expression#Select] instances.
\**kwargs
available keyword arguments are the same as those of
[sqlalchemy.sql.expression#select()].
"""
return _compound_select('EXCEPT', *selects, **kwargs)
def except_all(*selects, **kwargs):
"""Return an ``EXCEPT ALL`` of multiple selectables.
The returned object is an instance of [sqlalchemy.sql.expression#CompoundSelect].
\*selects
a list of [sqlalchemy.sql.expression#Select] instances.
\**kwargs
available keyword arguments are the same as those of
[sqlalchemy.sql.expression#select()].
"""
return _compound_select('EXCEPT ALL', *selects, **kwargs)
def intersect(*selects, **kwargs):
"""Return an ``INTERSECT`` of multiple selectables.
The returned object is an instance of [sqlalchemy.sql.expression#CompoundSelect].
\*selects
a list of [sqlalchemy.sql.expression#Select] instances.
\**kwargs
available keyword arguments are the same as those of
[sqlalchemy.sql.expression#select()].
"""
return _compound_select('INTERSECT', *selects, **kwargs)
def intersect_all(*selects, **kwargs):
"""Return an ``INTERSECT ALL`` of multiple selectables.
The returned object is an instance of [sqlalchemy.sql.expression#CompoundSelect].
\*selects
a list of [sqlalchemy.sql.expression#Select] instances.
\**kwargs
available keyword arguments are the same as those of
[sqlalchemy.sql.expression#select()].
"""
return _compound_select('INTERSECT ALL', *selects, **kwargs)
def alias(selectable, alias=None):
"""Return an [sqlalchemy.sql.expression#Alias] object.
An ``Alias`` represents any [sqlalchemy.sql.expression#FromClause] with
an alternate name assigned within SQL, typically using the ``AS``
clause when generated, e.g. ``SELECT * FROM table AS aliasname``.
Similar functionality is available via the ``alias()`` method
available on all ``FromClause`` subclasses.
selectable
any ``FromClause`` subclass, such as a table, select
statement, etc..
alias
string name to be assigned as the alias. If ``None``, a
random name will be generated.
"""
return Alias(selectable, alias=alias)
def literal(value, type_=None):
"""Return a literal clause, bound to a bind parameter.
Literal clauses are created automatically when non-
``ClauseElement`` objects (such as strings, ints, dates, etc.) are
used in a comparison operation with a
[sqlalchemy.sql.expression#_CompareMixin] subclass, such as a ``Column``
object. Use this function to force the generation of a literal
clause, which will be created as a
[sqlalchemy.sql.expression#_BindParamClause] with a bound value.
value
the value to be bound. Can be any Python object supported by
the underlying DB-API, or is translatable via the given type
argument.
type\_
an optional [sqlalchemy.types#TypeEngine] which will provide
bind-parameter translation for this literal.
"""
return _BindParamClause('literal', value, type_=type_, unique=True)
def label(name, obj):
"""Return a [sqlalchemy.sql.expression#_Label] object for the given [sqlalchemy.sql.expression#ColumnElement].
A label changes the name of an element in the columns clause of a
``SELECT`` statement, typically via the ``AS`` SQL keyword.
This functionality is more conveniently available via the
``label()`` method on ``ColumnElement``.
name
label name
obj
a ``ColumnElement``.
"""
return _Label(name, obj)
def column(text, type_=None):
"""Return a textual column clause, as would be in the columns clause of a ``SELECT`` statement.
The object returned is an instance of [sqlalchemy.sql.expression#_ColumnClause],
which represents the "syntactical" portion of the schema-level
[sqlalchemy.schema#Column] object.
text
the name of the column. Quoting rules will be applied to the
clause like any other column name. For textual column
constructs that are not to be quoted, use the
[sqlalchemy.sql.expression#literal_column()] function.
type\_
an optional [sqlalchemy.types#TypeEngine] object which will
provide result-set translation for this column.
"""
return _ColumnClause(text, type_=type_)
def literal_column(text, type_=None):
"""Return a textual column clause, as would be in the columns clause of a ``SELECT`` statement.
The object returned is an instance of [sqlalchemy.sql.expression#_ColumnClause],
which represents the "syntactical" portion of the schema-level
[sqlalchemy.schema#Column] object.
text
the name of the column. Quoting rules will not be applied to
the column. For textual column constructs that should be quoted
like any other column construct, use the
[sqlalchemy.sql.expression#column()] function.
type
an optional [sqlalchemy.types#TypeEngine] object which will
provide result-set translation for this column.
"""
return _ColumnClause(text, type_=type_, is_literal=True)
def table(name, *columns):
"""Return a [sqlalchemy.sql.expression#Table] object.
This is a primitive version of the [sqlalchemy.schema#Table] object,
which is a subclass of this object.
"""
return TableClause(name, *columns)
def bindparam(key, value=None, type_=None, shortname=None, unique=False):
"""Create a bind parameter clause with the given key.
value
a default value for this bind parameter. a bindparam with a
value is called a ``value-based bindparam``.
shortname
an ``alias`` for this bind parameter. usually used to alias the
``key`` nd ``label`` of a column, i.e. ``somecolname`` and
``sometable_somecolname``
type
a sqlalchemy.types.TypeEngine object indicating the type of this
bind param, will invoke type-specific bind parameter processing
unique
if True, bind params sharing the same name will have their
underlying ``key`` modified to a uniquely generated name.
mostly useful with value-based bind params.
"""
if isinstance(key, _ColumnClause):
return _BindParamClause(key.name, value, type_=key.type, shortname=shortname, unique=unique)
else:
return _BindParamClause(key, value, type_=type_, shortname=shortname, unique=unique)
def outparam(key, type_=None):
"""Create an 'OUT' parameter for usage in functions (stored procedures), for databases which support them.
The ``outparam`` can be used like a regular function parameter.
The "output" value will be available from the
[sqlalchemy.engine#ResultProxy] object via its ``out_parameters``
attribute, which returns a dictionary containing the values.
"""
return _BindParamClause(key, None, type_=type_, unique=False, isoutparam=True)
def text(text, bind=None, *args, **kwargs):
"""Create literal text to be inserted into a query.
When constructing a query from a ``select()``, ``update()``,
``insert()`` or ``delete()``, using plain strings for argument
values will usually result in text objects being created
automatically. Use this function when creating textual clauses
outside of other ``ClauseElement`` objects, or optionally wherever
plain text is to be used.
text
the text of the SQL statement to be created. use ``:<param>``
to specify bind parameters; they will be compiled to their
engine-specific format.
bind
an optional connection or engine to be used for this text query.
bindparams
a list of ``bindparam()`` instances which can be used to define
the types and/or initial values for the bind parameters within
the textual statement; the keynames of the bindparams must match
those within the text of the statement. The types will be used
for pre-processing on bind values.
typemap
a dictionary mapping the names of columns represented in the
``SELECT`` clause of the textual statement to type objects,
which will be used to perform post-processing on columns within
the result set (for textual statements that produce result
sets).
"""
return _TextClause(text, bind=bind, *args, **kwargs)
def null():
"""Return a ``_Null`` object, which compiles to ``NULL`` in a sql statement."""
return _Null()
class _FunctionGenerator(object):
"""Generate ``_Function`` objects based on getattr calls."""
def __init__(self, **opts):
self.__names = []
self.opts = opts
def __getattr__(self, name):
# passthru __ attributes; fixes pydoc
if name.startswith('__'):
try:
return self.__dict__[name]
except KeyError:
raise AttributeError(name)
elif name.startswith('_'):
name = name[0:-1]
f = _FunctionGenerator(**self.opts)
f.__names = list(self.__names) + [name]
return f
def __call__(self, *c, **kwargs):
o = self.opts.copy()
o.update(kwargs)
return _Function(self.__names[-1], packagenames=self.__names[0:-1], *c, **o)
func = _FunctionGenerator()
# TODO: use UnaryExpression for this instead ?
modifier = _FunctionGenerator(group=False)
def _compound_select(keyword, *selects, **kwargs):
return CompoundSelect(keyword, *selects, **kwargs)
def _is_literal(element):
return not isinstance(element, ClauseElement)
def _literal_as_text(element):
if isinstance(element, Operators):
return element.expression_element()
elif _is_literal(element):
return _TextClause(unicode(element))
else:
return element
def _literal_as_column(element):
if isinstance(element, Operators):
return element.clause_element()
elif _is_literal(element):
return literal_column(str(element))
else:
return element
def _literal_as_binds(element, name='literal', type_=None):
if isinstance(element, Operators):
return element.expression_element()
elif _is_literal(element):
if element is None:
return null()
else:
return _BindParamClause(name, element, shortname=name, type_=type_, unique=True)
else:
return element
def _selectable(element):
if hasattr(element, '__selectable__'):
return element.__selectable__()
elif isinstance(element, Selectable):
return element
else:
raise exceptions.ArgumentError("Object '%s' is not a Selectable and does not implement `__selectable__()`" % repr(element))
def is_column(col):
"""True if ``col`` is an instance of ``ColumnElement``."""
return isinstance(col, ColumnElement)
class _FigureVisitName(type):
def __init__(cls, clsname, bases, dict):
if not '__visit_name__' in cls.__dict__:
m = re.match(r'_?(\w+?)(?:Expression|Clause|Element|$)', clsname)
x = m.group(1)
x = re.sub(r'(?!^)[A-Z]', lambda m:'_'+m.group(0).lower(), x)
cls.__visit_name__ = x.lower()
super(_FigureVisitName, cls).__init__(clsname, bases, dict)
class ClauseElement(object):
"""Base class for elements of a programmatically constructed SQL expression."""
__metaclass__ = _FigureVisitName
def _clone(self):
"""Create a shallow copy of this ClauseElement.
This method may be used by a generative API. Its also used as
part of the "deep" copy afforded by a traversal that combines
the _copy_internals() method.
"""
c = self.__class__.__new__(self.__class__)
c.__dict__ = self.__dict__.copy()
return c
def _get_from_objects(self, **modifiers):
"""Return objects represented in this ``ClauseElement`` that
should be added to the ``FROM`` list of a query, when this
``ClauseElement`` is placed in the column clause of a
``Select`` statement.
"""
raise NotImplementedError(repr(self))
def _hide_froms(self, **modifiers):
"""Return a list of ``FROM`` clause elements which this ``ClauseElement`` replaces."""
return []
def unique_params(self, *optionaldict, **kwargs):
"""Return a copy with ``bindparam()`` elments replaced.
Same functionality as ``params()``, except adds `unique=True`
to affected bind parameters so that multiple statements can be
used.
"""
return self._params(True, optionaldict, kwargs)
def params(self, *optionaldict, **kwargs):
"""Return a copy with ``bindparam()`` elments replaced.
Returns a copy of this ClauseElement with ``bindparam()``
elements replaced with values taken from the given dictionary::
>>> clause = column('x') + bindparam('foo')
>>> print clause.compile().params
{'foo':None}
>>> print clause.params({'foo':7}).compile().params
{'foo':7}
"""
return self._params(False, optionaldict, kwargs)
def _params(self, unique, optionaldict, kwargs):
if len(optionaldict) == 1:
kwargs.update(optionaldict[0])
elif len(optionaldict) > 1:
raise exceptions.ArgumentError("params() takes zero or one positional dictionary argument")
class Vis(visitors.ClauseVisitor):
def visit_bindparam(self, bind):
if bind.key in kwargs:
bind.value = kwargs[bind.key]
if unique:
bind.unique=True
return Vis().traverse(self, clone=True)
def compare(self, other):
"""Compare this ClauseElement to the given ClauseElement.
Subclasses should override the default behavior, which is a
straight identity comparison.
"""
return self is other
def _copy_internals(self):
"""Reassign internal elements to be clones of themselves.
Called during a copy-and-traverse operation on newly
shallow-copied elements to create a deep copy.
"""
pass
def get_children(self, **kwargs):
"""Return immediate child elements of this ``ClauseElement``.
This is used for visit traversal.
\**kwargs may contain flags that change the collection that is
returned, for example to return a subset of items in order to
cut down on larger traversals, or to return child items from a
different context (such as schema-level collections instead of
clause-level).
"""
return []
def self_group(self, against=None):
return self
def supports_execution(self):
"""Return True if this clause element represents a complete executable statement."""
return False
def _find_engine(self):
"""Default strategy for locating an engine within the clause element.
Relies upon a local engine property, or looks in the *from*
objects which ultimately have to contain Tables or
TableClauses.
"""
try:
if self._bind is not None:
return self._bind
except AttributeError:
pass
for f in self._get_from_objects():
if f is self:
continue
engine = f.bind
if engine is not None:
return engine
else:
return None
bind = property(lambda s:s._find_engine(), doc="""Returns the Engine or Connection to which this ClauseElement is bound, or None if none found.""")
def execute(self, *multiparams, **params):
"""Compile and execute this ``ClauseElement``."""
e = self.bind
if e is None:
raise exceptions.InvalidRequestError("This Compiled object is not bound to any Engine or Connection.")
return e._execute_clauseelement(self, multiparams, params)
def scalar(self, *multiparams, **params):
"""Compile and execute this ``ClauseElement``, returning the result's scalar representation."""
return self.execute(*multiparams, **params).scalar()
def compile(self, bind=None, column_keys=None, compiler=None, dialect=None, inline=False):
"""Compile this SQL expression.
Uses the given ``Compiler``, or the given ``AbstractDialect``
or ``Engine`` to create a ``Compiler``. If no `compiler`
arguments are given, tries to use the underlying ``Engine``
this ``ClauseElement`` is bound to to create a ``Compiler``,
if any.
Finally, if there is no bound ``Engine``, uses an
``DefaultDialect`` to create a default ``Compiler``.
`parameters` is a dictionary representing the default bind
parameters to be used with the statement. If `parameters` is
a list, it is assumed to be a list of dictionaries and the
first dictionary in the list is used with which to compile
against.
The bind parameters can in some cases determine the output of
the compilation, such as for ``UPDATE`` and ``INSERT``
statements the bind parameters that are present determine the
``SET`` and ``VALUES`` clause of those statements.
"""
if compiler is None:
if dialect is not None:
compiler = dialect.statement_compiler(dialect, self, column_keys=column_keys, inline=inline)
elif bind is not None:
compiler = bind.statement_compiler(self, column_keys=column_keys, inline=inline)
elif self.bind is not None:
compiler = self.bind.statement_compiler(self, column_keys=column_keys, inline=inline)
if compiler is None:
from sqlalchemy.engine.default import DefaultDialect
dialect = DefaultDialect()
compiler = dialect.statement_compiler(dialect, self, column_keys=column_keys, inline=inline)
compiler.compile()
return compiler
def __str__(self):
return unicode(self.compile()).encode('ascii', 'backslashreplace')
def __and__(self, other):
return and_(self, other)
def __or__(self, other):
return or_(self, other)
def __invert__(self):
return self._negate()
def _negate(self):
if hasattr(self, 'negation_clause'):
return self.negation_clause
else:
return _UnaryExpression(self.self_group(against=operators.inv), operator=operators.inv, negate=None)
class Operators(object):
def __and__(self, other):
return self.operate(operators.and_, other)
def __or__(self, other):
return self.operate(operators.or_, other)
def __invert__(self):
return self.operate(operators.inv)
def clause_element(self):
raise NotImplementedError()
def operate(self, op, *other, **kwargs):
raise NotImplementedError()
def reverse_operate(self, op, other, **kwargs):
raise NotImplementedError()
class ColumnOperators(Operators):
"""Defines comparison and math operations."""
def __lt__(self, other):
return self.operate(operators.lt, other)
def __le__(self, other):
return self.operate(operators.le, other)
def __eq__(self, other):
return self.operate(operators.eq, other)
def __ne__(self, other):
return self.operate(operators.ne, other)
def __gt__(self, other):
return self.operate(operators.gt, other)
def __ge__(self, other):
return self.operate(operators.ge, other)
def concat(self, other):
return self.operate(operators.concat_op, other)
def like(self, other):
return self.operate(operators.like_op, other)
def in_(self, *other):
return self.operate(operators.in_op, other)
def startswith(self, other):
return self.operate(operators.startswith_op, other)
def endswith(self, other):
return self.operate(operators.endswith_op, other)
def contains(self, other):
return self.operate(operators.contains_op, other)
def desc(self):
return self.operate(operators.desc_op)
def asc(self):
return self.operate(operators.asc_op)
def __radd__(self, other):
return self.reverse_operate(operators.add, other)
def __rsub__(self, other):
return self.reverse_operate(operators.sub, other)
def __rmul__(self, other):
return self.reverse_operate(operators.mul, other)
def __rdiv__(self, other):
return self.reverse_operate(operators.div, other)
def between(self, cleft, cright):
return self.operate(operators.between_op, cleft, cright)
def distinct(self):
return self.operate(operators.distinct_op)
def __add__(self, other):
return self.operate(operators.add, other)
def __sub__(self, other):
return self.operate(operators.sub, other)
def __mul__(self, other):
return self.operate(operators.mul, other)
def __div__(self, other):
return self.operate(operators.div, other)
def __mod__(self, other):
return self.operate(operators.mod, other)
def __truediv__(self, other):
return self.operate(operators.truediv, other)
# precedence ordering for common operators. if an operator is not
# present in this list, it will be parenthesized when grouped against
# other operators
_smallest = object()
_largest = object()
PRECEDENCE = {
operators.from_:15,
operators.mul:7,
operators.div:7,
operators.mod:7,
operators.add:6,
operators.sub:6,
operators.concat_op:6,
operators.ilike_op:5,
operators.notilike_op:5,
operators.like_op:5,
operators.notlike_op:5,
operators.in_op:5,
operators.notin_op:5,
operators.is_:5,
operators.isnot:5,
operators.eq:5,
operators.ne:5,
operators.gt:5,
operators.lt:5,
operators.ge:5,
operators.le:5,
operators.between_op:5,
operators.distinct_op:5,
operators.inv:5,
operators.and_:3,
operators.or_:2,
operators.comma_op:-1,
operators.as_:-1,
operators.exists:0,
_smallest: -1000,
_largest: 1000
}
class _CompareMixin(ColumnOperators):
"""Defines comparison and math operations for ``ClauseElement`` instances."""
def __compare(self, op, obj, negate=None):
if obj is None or isinstance(obj, _Null):
if op == operators.eq:
return _BinaryExpression(self.expression_element(), null(), operators.is_, negate=operators.isnot)
elif op == operators.ne:
return _BinaryExpression(self.expression_element(), null(), operators.isnot, negate=operators.is_)
else:
raise exceptions.ArgumentError("Only '='/'!=' operators can be used with NULL")
else:
obj = self._check_literal(obj)
return _BinaryExpression(self.expression_element(), obj, op, type_=sqltypes.Boolean, negate=negate)
def __operate(self, op, obj):
obj = self._check_literal(obj)
type_ = self._compare_type(obj)
# TODO: generalize operator overloading like this out into the
# types module
if op == operators.add and isinstance(type_, (sqltypes.Concatenable)):
op = operators.concat_op
return _BinaryExpression(self.expression_element(), obj, op, type_=type_)
# a mapping of operators with the method they use, along with their negated
# operator for comparison operators
operators = {
operators.add : (__operate,),
operators.mul : (__operate,),
operators.sub : (__operate,),
operators.div : (__operate,),
operators.mod : (__operate,),
operators.truediv : (__operate,),
operators.lt : (__compare, operators.ge),
operators.le : (__compare, operators.gt),
operators.ne : (__compare, operators.eq),
operators.gt : (__compare, operators.le),
operators.ge : (__compare, operators.lt),
operators.eq : (__compare, operators.ne),
operators.like_op : (__compare, operators.notlike_op),
}
def operate(self, op, *other):
o = _CompareMixin.operators[op]
return o[0](self, op, other[0], *o[1:])
def reverse_operate(self, op, other):
return self._bind_param(other).operate(op, self)
def in_(self, *other):
return self._in_impl(operators.in_op, operators.notin_op, *other)
def _in_impl(self, op, negate_op, *other):
# Handle old style *args argument passing
if len(other) != 1 or not isinstance(other[0], Selectable) and (not hasattr(other[0], '__iter__') or isinstance(other[0], basestring)):
util.warn_deprecated('passing in_ arguments as varargs is deprecated, in_ takes a single argument that is a sequence or a selectable')
seq_or_selectable = other
else:
seq_or_selectable = other[0]
if isinstance(seq_or_selectable, Selectable):
return self.__compare( op, seq_or_selectable, negate=negate_op)
# Handle non selectable arguments as sequences
args = []
for o in seq_or_selectable:
if not _is_literal(o):
if not isinstance( o, _CompareMixin):
raise exceptions.InvalidRequestError( "in() function accepts either a list of non-selectable values, or a selectable: "+repr(o) )
else:
o = self._bind_param(o)
args.append(o)
if len(args) == 0:
# Special case handling for empty IN's
return _Grouping(case([(self.__eq__(None), text('NULL'))], else_=text('0')).__eq__(text('1')))
return self.__compare(op, ClauseList(*args).self_group(against=op), negate=negate_op)
def startswith(self, other):
"""Produce the clause ``LIKE '<other>%'``"""
perc = isinstance(other, basestring) and '%' or literal('%', type_=sqltypes.String)
return self.__compare(operators.like_op, other + perc)
def endswith(self, other):
"""Produce the clause ``LIKE '%<other>'``"""
if isinstance(other, basestring):
po = '%' + other
else:
po = literal('%', type_=sqltypes.String) + other
po.type = sqltypes.to_instance(sqltypes.String) #force!
return self.__compare(operators.like_op, po)
def contains(self, other):
"""Produce the clause ``LIKE '%<other>%'``"""
if isinstance(other, basestring):
po = '%' + other + '%'
else:
perc = literal('%', type_=sqltypes.String)
po = perc + other + perc
po.type = sqltypes.to_instance(sqltypes.String) #force!
return self.__compare(operators.like_op, po)
def label(self, name):
"""Produce a column label, i.e. ``<columnname> AS <name>``"""
return _Label(name, self, self.type)
def desc(self):
"""Produce a DESC clause, i.e. ``<columnname> DESC``"""
return desc(self)
def asc(self):
"""Produce a ASC clause, i.e. ``<columnname> ASC``"""
return asc(self)
def distinct(self):
"""Produce a DISTINCT clause, i.e. ``DISTINCT <columnname>``"""
return _UnaryExpression(self, operator=operators.distinct_op)
def between(self, cleft, cright):
"""Produce a BETWEEN clause, i.e. ``<column> BETWEEN <cleft> AND <cright>``"""
return _BinaryExpression(self, ClauseList(self._check_literal(cleft), self._check_literal(cright), operator=operators.and_, group=False), operators.between_op)
def op(self, operator):
"""produce a generic operator function.
e.g.::
somecolumn.op("*")(5)
produces::
somecolumn * 5
operator
a string which will be output as the infix operator between
this ``ClauseElement`` and the expression passed to the
generated function.
"""
return lambda other: self.__operate(operator, other)
def _bind_param(self, obj):
return _BindParamClause('literal', obj, shortname=None, type_=self.type, unique=True)
def _check_literal(self, other):
if isinstance(other, Operators):
return other.expression_element()
elif _is_literal(other):
return self._bind_param(other)
else:
return other
def clause_element(self):
"""Allow ``_CompareMixins`` to return the underlying ``ClauseElement``, for non-``ClauseElement`` ``_CompareMixins``."""
return self
def expression_element(self):
"""Allow ``_CompareMixins`` to return the appropriate object to be used in expressions."""
return self
def _compare_type(self, obj):
"""Allow subclasses to override the type used in constructing
``_BinaryExpression`` objects.
Default return value is the type of the given object.
"""
return obj.type
class ColumnElement(ClauseElement, _CompareMixin):
"""Represent an element that is usable within the "column clause" portion of a ``SELECT`` statement.
This includes columns associated with tables, aliases, and
subqueries, expressions, function calls, SQL keywords such as
``NULL``, literals, etc. ``ColumnElement`` is the ultimate base
class for all such elements.
``ColumnElement`` supports the ability to be a *proxy* element,
which indicates that the ``ColumnElement`` may be associated with
a ``Selectable`` which was derived from another ``Selectable``.
An example of a "derived" ``Selectable`` is an ``Alias`` of a
``Table``.
A ``ColumnElement``, by subclassing the ``_CompareMixin`` mixin
class, provides the ability to generate new ``ClauseElement``
objects using Python expressions. See the ``_CompareMixin``
docstring for more details.
"""
primary_key = property(lambda self:getattr(self, '_primary_key', False),
doc=\
"""Primary key flag. Indicates if this ``Column`` represents part or
whole of a primary key for its parent table.
""")
foreign_keys = property(lambda self:getattr(self, '_foreign_keys', []),
doc=\
"""Foreign key accessor. References a list of ``ForeignKey`` objects
which each represent a foreign key placed on this column's ultimate
ancestor.
""")
def _one_fkey(self):
if self._foreign_keys:
return list(self._foreign_keys)[0]
else:
return None
foreign_key = property(_one_fkey)
def _get_orig_set(self):
try:
return self.__orig_set
except AttributeError:
self.__orig_set = util.Set([self])
return self.__orig_set
def _set_orig_set(self, s):
if len(s) == 0:
s.add(self)
self.__orig_set = s
orig_set = property(_get_orig_set, _set_orig_set,
doc=\
"""A Set containing TableClause-bound, non-proxied ColumnElements
for which this ColumnElement is a proxy. In all cases except
for a column proxied from a Union (i.e. CompoundSelect), this
set will be just one element.
""")
def shares_lineage(self, othercolumn):
"""Return True if the given ``ColumnElement`` has a common ancestor to this ``ColumnElement``.
"""
for c in self.orig_set:
if c in othercolumn.orig_set:
return True
else:
return False
def _make_proxy(self, selectable, name=None):
"""Create a new ``ColumnElement`` representing this
``ColumnElement`` as it appears in the select list of a
descending selectable.
The default implementation returns a ``_ColumnClause`` if a
name is given, else just returns self.
"""
if name is not None:
co = _ColumnClause(name, selectable)
co.orig_set = self.orig_set
selectable.columns[name]= co
return co
else:
return self
class ColumnCollection(util.OrderedProperties):
"""An ordered dictionary that stores a list of ColumnElement
instances.
Overrides the ``__eq__()`` method to produce SQL clauses between
sets of correlated columns.
"""
def __init__(self, *cols):
super(ColumnCollection, self).__init__()
[self.add(c) for c in cols]
def __str__(self):
return repr([str(c) for c in self])
def add(self, column):
"""Add a column to this collection.
The key attribute of the column will be used as the hash key
for this dictionary.
"""
# Allow an aliased column to replace an unaliased column of the
# same name.
if column.name in self:
other = self[column.name]
if other.name == other.key:
del self[other.name]
self[column.key] = column
def remove(self, column):
del self[column.key]
def extend(self, iter):
for c in iter:
self.add(c)
def __eq__(self, other):
l = []
for c in other:
for local in self:
if c.shares_lineage(local):
l.append(c==local)
return and_(*l)
def __contains__(self, other):
if not isinstance(other, basestring):
raise exceptions.ArgumentError("__contains__ requires a string argument")
return util.OrderedProperties.__contains__(self, other)
def contains_column(self, col):
# have to use a Set here, because it will compare the identity
# of the column, not just using "==" for comparison which will always return a
# "True" value (i.e. a BinaryClause...)
return col in util.Set(self)
class ColumnSet(util.OrderedSet):
def contains_column(self, col):
return col in self
def extend(self, cols):
for col in cols:
self.add(col)
def __add__(self, other):
return list(self) + list(other)
def __eq__(self, other):
l = []
for c in other:
for local in self:
if c.shares_lineage(local):
l.append(c==local)
return and_(*l)
class Selectable(ClauseElement):
"""mark a class as being selectable"""
class FromClause(Selectable):
"""Represent an element that can be used within the ``FROM`` clause of a ``SELECT`` statement."""
__visit_name__ = 'fromclause'
def __init__(self, name=None):
self.name = name
self.oid_column = None
def _get_from_objects(self, **modifiers):
# this could also be [self], at the moment it doesnt matter to the Select object
return []
def default_order_by(self):
return [self.oid_column]
def count(self, whereclause=None, **params):
"""return a SELECT COUNT generated against this ``FromClause``."""
if self.primary_key:
col = list(self.primary_key)[0]
else:
col = list(self.columns)[0]
return select([func.count(col).label('tbl_row_count')], whereclause, from_obj=[self], **params)
def select(self, whereclauses = None, **params):
"""return a SELECT of this ``FromClause``."""
return select([self], whereclauses, **params)
def join(self, right, *args, **kwargs):
"""return a join of this ``FromClause`` against another ``FromClause``."""
return Join(self, right, *args, **kwargs)
def outerjoin(self, right, *args, **kwargs):
"""return an outer join of this ``FromClause`` against another ``FromClause``."""
return Join(self, right, isouter=True, *args, **kwargs)
def alias(self, name=None):
"""return an alias of this ``FromClause`` against another ``FromClause``."""
return Alias(self, name)
def named_with_column(self):
"""True if the name of this FromClause may be prepended to a
column in a generated SQL statement.
"""
return False
def _get_all_embedded_columns(self):
ret = []
class FindCols(visitors.ClauseVisitor):
def visit_column(self, col):
ret.append(col)
FindCols().traverse(self)
return ret
def is_derived_from(self, fromclause):
"""Return True if this FromClause is 'derived' from the given FromClause.
An example would be an Alias of a Table is derived from that Table.
"""
return False
def replace_selectable(self, old, alias):
"""replace all occurences of FromClause 'old' with the given Alias object, returning a copy of this ``FromClause``."""
from sqlalchemy.sql import util
return util.ClauseAdapter(alias).traverse(self, clone=True)
def corresponding_column(self, column, raiseerr=True, keys_ok=False, require_embedded=False):
"""Given a ``ColumnElement``, return the exported ``ColumnElement``
object from this ``Selectable`` which corresponds to that
original ``Column`` via a common anscestor column.
column
the target ``ColumnElement`` to be matched
raiseerr
if True, raise an error if the given ``ColumnElement`` could
not be matched. if False, non-matches will return None.
keys_ok
if the ``ColumnElement`` cannot be matched, attempt to match
based on the string "key" property of the column alone. This
makes the search much more liberal.
require_embedded
only return corresponding columns for the given
``ColumnElement``, if the given ``ColumnElement`` is
actually present within a sub-element of this
``FromClause``. Normally the column will match if it merely
shares a common anscestor with one of the exported columns
of this ``FromClause``.
"""
if self.c.contains_column(column):
return column
if require_embedded and column not in util.Set(self._get_all_embedded_columns()):
if not raiseerr:
return None
else:
raise exceptions.InvalidRequestError("Column instance '%s' is not directly present within selectable '%s'" % (str(column), column.table))
for c in column.orig_set:
try:
return self.original_columns[c]
except KeyError:
pass
else:
if keys_ok:
try:
return self.c[column.name]
except KeyError:
pass
if not raiseerr:
return None
else:
raise exceptions.InvalidRequestError("Given column '%s', attached to table '%s', failed to locate a corresponding column from table '%s'" % (str(column), str(getattr(column, 'table', None)), self.name))
def _clone_from_clause(self):
# delete all the "generated" collections of columns for a
# newly cloned FromClause, so that they will be re-derived
# from the item. this is because FromClause subclasses, when
# cloned, need to reestablish new "proxied" columns that are
# linked to the new item
for attr in ('_columns', '_primary_key' '_foreign_keys', '_orig_cols', '_oid_column'):
if hasattr(self, attr):
delattr(self, attr)
def _expr_attr_func(name):
def attr(self):
try:
return getattr(self, name)
except AttributeError:
self._export_columns()
return getattr(self, name)
return attr
columns = property(_expr_attr_func('_columns'))
c = property(_expr_attr_func('_columns'))
primary_key = property(_expr_attr_func('_primary_key'))
foreign_keys = property(_expr_attr_func('_foreign_keys'))
original_columns = property(_expr_attr_func('_orig_cols'), doc=\
"""A dictionary mapping an original Table-bound
column to a proxied column in this FromClause.
""")
def _export_columns(self, columns=None):
"""Initialize column collections.
The collections include the primary key, foreign keys, list of
all columns, as well as the *_orig_cols* collection which is a
dictionary used to match Table-bound columns to proxied
columns in this ``FromClause``. The columns in each
collection are *proxied* from the columns returned by the
_exportable_columns method, where a *proxied* column maintains
most or all of the properties of its original column, except
its parent ``Selectable`` is this ``FromClause``.
"""
if hasattr(self, '_columns') and columns is None:
return
self._columns = ColumnCollection()
self._primary_key = ColumnSet()
self._foreign_keys = util.Set()
self._orig_cols = {}
if columns is None:
columns = self._flatten_exportable_columns()
for co in columns:
cp = self._proxy_column(co)
for ci in cp.orig_set:
cx = self._orig_cols.get(ci)
# TODO: the '=' thing here relates to the order of
# columns as they are placed in the "columns"
# collection of a CompositeSelect, illustrated in
# test/sql/selectable.SelectableTest.testunion make
# this relationship less brittle
if cx is None or cp._distance <= cx._distance:
self._orig_cols[ci] = cp
if self.oid_column is not None:
for ci in self.oid_column.orig_set:
self._orig_cols[ci] = self.oid_column
def _flatten_exportable_columns(self):
"""Return the list of ColumnElements represented within this FromClause's _exportable_columns"""
export = self._exportable_columns()
for column in export:
if isinstance(column, Selectable):
for co in column.columns:
yield co
elif isinstance(column, ColumnElement):
yield column
else:
continue
def _exportable_columns(self):
return []
def _proxy_column(self, column):
return column._make_proxy(self)
class _BindParamClause(ClauseElement, _CompareMixin):
"""Represent a bind parameter.
Public constructor is the ``bindparam()`` function.
"""
__visit_name__ = 'bindparam'
def __init__(self, key, value, shortname=None, type_=None, unique=False, isoutparam=False):
"""Construct a _BindParamClause.
key
the key for this bind param. Will be used in the generated
SQL statement for dialects that use named parameters. This
value may be modified when part of a compilation operation,
if other ``_BindParamClause`` objects exist with the same
key, or if its length is too long and truncation is
required.
value
Initial value for this bind param. This value may be
overridden by the dictionary of parameters sent to statement
compilation/execution.
shortname
Defaults to the key, a *short name* that will also identify
this bind parameter, similar to an alias. the bind
parameter keys sent to a statement compilation or compiled
execution may match either the key or the shortname of the
corresponding ``_BindParamClause`` objects.
type\_
A ``TypeEngine`` object that will be used to pre-process the
value corresponding to this ``_BindParamClause`` at
execution time.
unique
if True, the key name of this BindParamClause will be
modified if another ``_BindParamClause`` of the same name
already has been located within the containing
``ClauseElement``.
isoutparam
if True, the parameter should be treated like a stored procedure "OUT"
parameter.
"""
self.key = key or "{ANON %d param}" % id(self)
self.value = value
self.shortname = shortname or key
self.unique = unique
self.isoutparam = isoutparam
if type_ is None:
self.type = self.type_map.get(type(value), sqltypes.NullType)()
elif isinstance(type_, type):
self.type = type_()
else:
self.type = type_
# TODO: move to types module, obviously
# using VARCHAR/NCHAR so that we dont get the genericized "String"
# type which usually resolves to TEXT/CLOB
type_map = {
str : sqltypes.VARCHAR,
unicode : sqltypes.NCHAR,
int : sqltypes.Integer,
float : sqltypes.Numeric,
type(None):sqltypes.NullType
}
def _get_from_objects(self, **modifiers):
return []
def bind_processor(self, dialect):
return self.type.dialect_impl(dialect).bind_processor(dialect)
def _compare_type(self, obj):
if not isinstance(self.type, sqltypes.NullType):
return self.type
else:
return obj.type
def compare(self, other):
"""Compare this ``_BindParamClause`` to the given clause.
Since ``compare()`` is meant to compare statement syntax, this
method returns True if the two ``_BindParamClauses`` have just
the same type.
"""
return isinstance(other, _BindParamClause) and other.type.__class__ == self.type.__class__
def __repr__(self):
return "_BindParamClause(%s, %s, type_=%s)" % (repr(self.key), repr(self.value), repr(self.type))
class _TypeClause(ClauseElement):
"""Handle a type keyword in a SQL statement.
Used by the ``Case`` statement.
"""
__visit_name__ = 'typeclause'
def __init__(self, type):
self.type = type
def _get_from_objects(self, **modifiers):
return []
class _TextClause(ClauseElement):
"""Represent a literal SQL text fragment.
Public constructor is the ``text()`` function.
"""
__visit_name__ = 'textclause'
def __init__(self, text = "", bind=None, bindparams=None, typemap=None):
self._bind = bind
self.bindparams = {}
self.typemap = typemap
if typemap is not None:
for key in typemap.keys():
typemap[key] = sqltypes.to_instance(typemap[key])
def repl(m):
self.bindparams[m.group(1)] = bindparam(m.group(1))
return ":%s" % m.group(1)
# scan the string and search for bind parameter names, add them
# to the list of bindparams
self.text = BIND_PARAMS.sub(repl, text)
if bindparams is not None:
for b in bindparams:
self.bindparams[b.key] = b
def _get_type(self):
if self.typemap is not None and len(self.typemap) == 1:
return list(self.typemap)[0]
else:
return None
type = property(_get_type)
columns = property(lambda s:[])
def _copy_internals(self):
self.bindparams = dict([(b.key, b._clone()) for b in self.bindparams.values()])
def get_children(self, **kwargs):
return self.bindparams.values()
def _get_from_objects(self, **modifiers):
return []
def supports_execution(self):
return True
def _table_iterator(self):
return iter([])
class _Null(ColumnElement):
"""Represent the NULL keyword in a SQL statement.
Public constructor is the ``null()`` function.
"""
def __init__(self):
self.type = sqltypes.NULLTYPE
def _get_from_objects(self, **modifiers):
return []
class ClauseList(ClauseElement):
"""Describe a list of clauses, separated by an operator.
By default, is comma-separated, such as a column listing.
"""
__visit_name__ = 'clauselist'
def __init__(self, *clauses, **kwargs):
self.clauses = []
self.operator = kwargs.pop('operator', operators.comma_op)
self.group = kwargs.pop('group', True)
self.group_contents = kwargs.pop('group_contents', True)
for c in clauses:
if c is None:
continue
self.append(c)
def __iter__(self):
return iter(self.clauses)
def __len__(self):
return len(self.clauses)
def append(self, clause):
# TODO: not sure if i like the 'group_contents' flag. need to
# define the difference between a ClauseList of ClauseLists,
# and a "flattened" ClauseList of ClauseLists. flatten()
# method ?
if self.group_contents:
self.clauses.append(_literal_as_text(clause).self_group(against=self.operator))
else:
self.clauses.append(_literal_as_text(clause))
def _copy_internals(self):
self.clauses = [clause._clone() for clause in self.clauses]
def get_children(self, **kwargs):
return self.clauses
def _get_from_objects(self, **modifiers):
f = []
for c in self.clauses:
f += c._get_from_objects(**modifiers)
return f
def self_group(self, against=None):
if self.group and self.operator != against and PRECEDENCE.get(self.operator, PRECEDENCE[_smallest]) <= PRECEDENCE.get(against, PRECEDENCE[_largest]):
return _Grouping(self)
else:
return self
def compare(self, other):
"""Compare this ``ClauseList`` to the given ``ClauseList``,
including a comparison of all the clause items.
"""
if not isinstance(other, ClauseList) and len(self.clauses) == 1:
return self.clauses[0].compare(other)
elif isinstance(other, ClauseList) and len(self.clauses) == len(other.clauses):
for i in range(0, len(self.clauses)):
if not self.clauses[i].compare(other.clauses[i]):
return False
else:
return self.operator == other.operator
else:
return False
class _CalculatedClause(ColumnElement):
"""Describe a calculated SQL expression that has a type, like ``CASE``.
Extends ``ColumnElement`` to provide column-level comparison
operators.
"""
__visit_name__ = 'calculatedclause'
def __init__(self, name, *clauses, **kwargs):
self.name = name
self.type = sqltypes.to_instance(kwargs.get('type_', None))
self._bind = kwargs.get('bind', None)
self.group = kwargs.pop('group', True)
clauses = ClauseList(operator=kwargs.get('operator', None), group_contents=kwargs.get('group_contents', True), *clauses)
if self.group:
self.clause_expr = clauses.self_group()
else:
self.clause_expr = clauses
key = property(lambda self:self.name or "_calc_")
def _copy_internals(self):
self.clause_expr = self.clause_expr._clone()
def clauses(self):
if isinstance(self.clause_expr, _Grouping):
return self.clause_expr.elem
else:
return self.clause_expr
clauses = property(clauses)
def get_children(self, **kwargs):
return self.clause_expr,
def _get_from_objects(self, **modifiers):
return self.clauses._get_from_objects(**modifiers)
def _bind_param(self, obj):
return _BindParamClause(self.name, obj, type_=self.type, unique=True)
def select(self):
return select([self])
def scalar(self):
return select([self]).execute().scalar()
def execute(self):
return select([self]).execute()
def _compare_type(self, obj):
return self.type
class _Function(_CalculatedClause, FromClause):
"""Describe a SQL function.
Extends ``_CalculatedClause``, turn the *clauselist* into function
arguments, also adds a `packagenames` argument.
"""
def __init__(self, name, *clauses, **kwargs):
self.packagenames = kwargs.get('packagenames', None) or []
self.oid_column = None
kwargs['operator'] = operators.comma_op
_CalculatedClause.__init__(self, name, **kwargs)
for c in clauses:
self.append(c)
key = property(lambda self:self.name)
columns = property(lambda self:[self])
def _copy_internals(self):
_CalculatedClause._copy_internals(self)
self._clone_from_clause()
def get_children(self, **kwargs):
return _CalculatedClause.get_children(self, **kwargs)
def append(self, clause):
self.clauses.append(_literal_as_binds(clause, self.name))
class _Cast(ColumnElement):
def __init__(self, clause, totype, **kwargs):
if not hasattr(clause, 'label'):
clause = literal(clause)
self.type = sqltypes.to_instance(totype)
self.clause = clause
self.typeclause = _TypeClause(self.type)
self._distance = 0
def _copy_internals(self):
self.clause = self.clause._clone()
self.typeclause = self.typeclause._clone()
def get_children(self, **kwargs):
return self.clause, self.typeclause
def _get_from_objects(self, **modifiers):
return self.clause._get_from_objects(**modifiers)
def _make_proxy(self, selectable, name=None):
if name is not None:
co = _ColumnClause(name, selectable, type_=self.type)
co._distance = self._distance + 1
co.orig_set = self.orig_set
selectable.columns[name]= co
return co
else:
return self
class _UnaryExpression(ColumnElement):
def __init__(self, element, operator=None, modifier=None, type_=None, negate=None):
self.operator = operator
self.modifier = modifier
self.element = _literal_as_text(element).self_group(against=self.operator or self.modifier)
self.type = sqltypes.to_instance(type_)
self.negate = negate
def _get_from_objects(self, **modifiers):
return self.element._get_from_objects(**modifiers)
def _copy_internals(self):
self.element = self.element._clone()
def get_children(self, **kwargs):
return self.element,
def compare(self, other):
"""Compare this ``_UnaryExpression`` against the given ``ClauseElement``."""
return (
isinstance(other, _UnaryExpression) and
self.operator == other.operator and
self.modifier == other.modifier and
self.element.compare(other.element)
)
def _negate(self):
if self.negate is not None:
return _UnaryExpression(self.element, operator=self.negate, negate=self.operator, modifier=self.modifier, type_=self.type)
else:
return super(_UnaryExpression, self)._negate()
def self_group(self, against):
if self.operator and PRECEDENCE.get(self.operator, PRECEDENCE[_smallest]) <= PRECEDENCE.get(against, PRECEDENCE[_largest]):
return _Grouping(self)
else:
return self
class _BinaryExpression(ColumnElement):
"""Represent an expression that is ``LEFT <operator> RIGHT``."""
def __init__(self, left, right, operator, type_=None, negate=None):
self.left = _literal_as_text(left).self_group(against=operator)
self.right = _literal_as_text(right).self_group(against=operator)
self.operator = operator
self.type = sqltypes.to_instance(type_)
self.negate = negate
def _get_from_objects(self, **modifiers):
return self.left._get_from_objects(**modifiers) + self.right._get_from_objects(**modifiers)
def _copy_internals(self):
self.left = self.left._clone()
self.right = self.right._clone()
def get_children(self, **kwargs):
return self.left, self.right
def compare(self, other):
"""Compare this ``_BinaryExpression`` against the given ``_BinaryExpression``."""
return (
isinstance(other, _BinaryExpression) and
self.operator == other.operator and
(
self.left.compare(other.left) and
self.right.compare(other.right) or
(
self.operator in [operators.eq, operators.ne,
operators.add, operators.mul] and
self.left.compare(other.right) and
self.right.compare(other.left)
)
)
)
def self_group(self, against=None):
# use small/large defaults for comparison so that unknown
# operators are always parenthesized
if self.operator != against and (PRECEDENCE.get(self.operator, PRECEDENCE[_smallest]) <= PRECEDENCE.get(against, PRECEDENCE[_largest])):
return _Grouping(self)
else:
return self
def _negate(self):
if self.negate is not None:
return _BinaryExpression(self.left, self.right, self.negate, negate=self.operator, type_=self.type)
else:
return super(_BinaryExpression, self)._negate()
class _Exists(_UnaryExpression):
__visit_name__ = _UnaryExpression.__visit_name__
def __init__(self, *args, **kwargs):
kwargs['correlate'] = True
s = select(*args, **kwargs).as_scalar().self_group()
_UnaryExpression.__init__(self, s, operator=operators.exists)
def select(self, whereclauses = None, **params):
return select([self], whereclauses, **params)
def correlate(self, fromclause):
e = self._clone()
e.element = self.element.correlate(fromclause).self_group()
return e
def where(self, clause):
e = self._clone()
e.element = self.element.where(clause).self_group()
return e
def _hide_froms(self, **modifiers):
return self._get_from_objects(**modifiers)
class Join(FromClause):
"""represent a ``JOIN`` construct between two ``FromClause`` elements.
The public constructor function for ``Join`` is the module-level
``join()`` function, as well as the ``join()`` method available
off all ``FromClause`` subclasses.
"""
def __init__(self, left, right, onclause=None, isouter = False):
self.left = _selectable(left)
self.right = _selectable(right).self_group()
self.oid_column = self.left.oid_column
if onclause is None:
self.onclause = self._match_primaries(self.left, self.right)
else:
self.onclause = onclause
self.isouter = isouter
self.__folded_equivalents = None
self._init_primary_key()
name = property(lambda s: "Join object on " + s.left.name + " " + s.right.name)
encodedname = property(lambda s: s.name.encode('ascii', 'backslashreplace'))
def _init_primary_key(self):
from sqlalchemy import schema
pkcol = util.Set([c for c in self._flatten_exportable_columns() if c.primary_key])
equivs = {}
def add_equiv(a, b):
for x, y in ((a, b), (b, a)):
if x in equivs:
equivs[x].add(y)
else:
equivs[x] = util.Set([y])
class BinaryVisitor(visitors.ClauseVisitor):
def visit_binary(self, binary):
if binary.operator == operators.eq and isinstance(binary.left, schema.Column) and isinstance(binary.right, schema.Column):
add_equiv(binary.left, binary.right)
BinaryVisitor().traverse(self.onclause)
for col in pkcol:
for fk in col.foreign_keys:
if fk.column in pkcol:
add_equiv(col, fk.column)
omit = util.Set()
for col in pkcol:
p = col
for c in equivs.get(col, util.Set()):
if p.references(c) or (c.primary_key and not p.primary_key):
omit.add(p)
p = c
self.__primary_key = ColumnSet([c for c in self._flatten_exportable_columns() if c.primary_key and c not in omit])
primary_key = property(lambda s:s.__primary_key)
def self_group(self, against=None):
return _FromGrouping(self)
def _exportable_columns(self):
return [c for c in self.left.columns] + [c for c in self.right.columns]
def _proxy_column(self, column):
self._columns[column._label] = column
for f in column.foreign_keys:
self._foreign_keys.add(f)
return column
def _copy_internals(self):
self._clone_from_clause()
self.left = self.left._clone()
self.right = self.right._clone()
self.onclause = self.onclause._clone()
self.__folded_equivalents = None
self._init_primary_key()
def get_children(self, **kwargs):
return self.left, self.right, self.onclause
def _match_primaries(self, primary, secondary):
crit = []
constraints = util.Set()
for fk in secondary.foreign_keys:
if fk.references(primary):
crit.append(primary.corresponding_column(fk.column) == fk.parent)
constraints.add(fk.constraint)
self.foreignkey = fk.parent
if primary is not secondary:
for fk in primary.foreign_keys:
if fk.references(secondary):
crit.append(secondary.corresponding_column(fk.column) == fk.parent)
constraints.add(fk.constraint)
self.foreignkey = fk.parent
if len(crit) == 0:
raise exceptions.ArgumentError(
"Can't find any foreign key relationships "
"between '%s' and '%s'" % (primary.name, secondary.name))
elif len(constraints) > 1:
raise exceptions.ArgumentError(
"Can't determine join between '%s' and '%s'; "
"tables have more than one foreign key "
"constraint relationship between them. "
"Please specify the 'onclause' of this "
"join explicitly." % (primary.name, secondary.name))
elif len(crit) == 1:
return (crit[0])
else:
return and_(*crit)
def _get_folded_equivalents(self, equivs=None):
if self.__folded_equivalents is not None:
return self.__folded_equivalents
if equivs is None:
equivs = util.Set()
class LocateEquivs(visitors.NoColumnVisitor):
def visit_binary(self, binary):
if binary.operator == operators.eq and binary.left.name == binary.right.name:
equivs.add(binary.right)
equivs.add(binary.left)
LocateEquivs().traverse(self.onclause)
collist = []
if isinstance(self.left, Join):
left = self.left._get_folded_equivalents(equivs)
else:
left = list(self.left.columns)
if isinstance(self.right, Join):
right = self.right._get_folded_equivalents(equivs)
else:
right = list(self.right.columns)
used = util.Set()
for c in left + right:
if c in equivs:
if c.name not in used:
collist.append(c)
used.add(c.name)
else:
collist.append(c)
self.__folded_equivalents = collist
return self.__folded_equivalents
folded_equivalents = property(_get_folded_equivalents, doc="Returns the column list of this Join with all equivalently-named, "
"equated columns folded into one column, where 'equated' means they are "
"equated to each other in the ON clause of this join.")
def select(self, whereclause = None, fold_equivalents=False, **kwargs):
"""Create a ``Select`` from this ``Join``.
whereclause
the WHERE criterion that will be sent to the ``select()``
function
fold_equivalents
based on the join criterion of this ``Join``, do not include
repeat column names in the column list of the resulting
select, for columns that are calculated to be "equivalent"
based on the join criterion of this ``Join``. This will
recursively apply to any joins directly nested by this one
as well.
\**kwargs
all other kwargs are sent to the underlying ``select()`` function.
See the ``select()`` module level function for details.
"""
if fold_equivalents:
collist = self.folded_equivalents
else:
collist = [self.left, self.right]
return select(collist, whereclause, from_obj=[self], **kwargs)
bind = property(lambda s:s.left.bind or s.right.bind)
def alias(self, name=None):
"""Create a ``Select`` out of this ``Join`` clause and return an ``Alias`` of it.
The ``Select`` is not correlating.
"""
return self.select(use_labels=True, correlate=False).alias(name)
def _hide_froms(self, **modifiers):
return self.left._get_from_objects(**modifiers) + self.right._get_from_objects(**modifiers)
def _get_from_objects(self, **modifiers):
return [self] + self.onclause._get_from_objects(**modifiers) + self.left._get_from_objects(**modifiers) + self.right._get_from_objects(**modifiers)
class Alias(FromClause):
"""Represents an table or selectable alias (AS).
Represents an alias, as typically applied to any table or
sub-select within a SQL statement using the ``AS`` keyword (or
without the keyword on certain databases such as Oracle).
This object is constructed from the ``alias()`` module level
function as well as the ``alias()`` method available on all
``FromClause`` subclasses.
"""
def __init__(self, selectable, alias=None):
baseselectable = selectable
while isinstance(baseselectable, Alias):
baseselectable = baseselectable.selectable
self.original = baseselectable
self.selectable = selectable
if alias is None:
if self.original.named_with_column():
alias = getattr(self.original, 'name', None)
alias = '{ANON %d %s}' % (id(self), alias or 'anon')
self.name = alias
self.encodedname = alias.encode('ascii', 'backslashreplace')
if self.selectable.oid_column is not None:
self.oid_column = self.selectable.oid_column._make_proxy(self)
else:
self.oid_column = None
def is_derived_from(self, fromclause):
x = self.selectable
while True:
if x is fromclause:
return True
if isinstance(x, Alias):
x = x.selectable
else:
break
return False
def supports_execution(self):
return self.original.supports_execution()
def _table_iterator(self):
return self.original._table_iterator()
def named_with_column(self):
return True
def _exportable_columns(self):
#return self.selectable._exportable_columns()
return self.selectable.columns
def _copy_internals(self):
self._clone_from_clause()
self.selectable = self.selectable._clone()
baseselectable = self.selectable
while isinstance(baseselectable, Alias):
baseselectable = baseselectable.selectable
self.original = baseselectable
def get_children(self, **kwargs):
for c in self.c:
yield c
yield self.selectable
def _get_from_objects(self, **modifiers):
return [self]
bind = property(lambda s: s.selectable.bind)
class _ColumnElementAdapter(ColumnElement):
"""Adapts a ClauseElement which may or may not be a
ColumnElement subclass itself into an object which
acts like a ColumnElement.
"""
def __init__(self, elem):
self.elem = elem
self.type = getattr(elem, 'type', None)
self.orig_set = getattr(elem, 'orig_set', util.Set())
key = property(lambda s: s.elem.key)
_label = property(lambda s: s.elem._label)
def _copy_internals(self):
self.elem = self.elem._clone()
def get_children(self, **kwargs):
return self.elem,
def _hide_froms(self, **modifiers):
return self.elem._hide_froms(**modifiers)
def _get_from_objects(self, **modifiers):
return self.elem._get_from_objects(**modifiers)
def __getattr__(self, attr):
return getattr(self.elem, attr)
class _Grouping(_ColumnElementAdapter):
"""Represent a grouping within a column expression"""
pass
class _FromGrouping(FromClause):
"""Represent a grouping of a FROM clause"""
__visit_name__ = 'grouping'
def __init__(self, elem):
self.elem = elem
columns = c = property(lambda s:s.elem.columns)
def get_children(self, **kwargs):
return self.elem,
def _hide_froms(self, **modifiers):
return self.elem._hide_froms(**modifiers)
def _copy_internals(self):
self.elem = self.elem._clone()
def _get_from_objects(self, **modifiers):
return self.elem._get_from_objects(**modifiers)
def __getattr__(self, attr):
return getattr(self.elem, attr)
class _Label(ColumnElement):
"""Represents a column label (AS).
Represent a label, as typically applied to any column-level
element using the ``AS`` sql keyword.
This object is constructed from the ``label()`` module level
function as well as the ``label()`` method available on all
``ColumnElement`` subclasses.
"""
def __init__(self, name, obj, type_=None):
while isinstance(obj, _Label):
obj = obj.obj
self.name = name or "{ANON %d %s}" % (id(self), getattr(obj, 'name', 'anon'))
self.obj = obj.self_group(against=operators.as_)
self.type = sqltypes.to_instance(type_ or getattr(obj, 'type', None))
key = property(lambda s: s.name)
_label = property(lambda s: s.name)
orig_set = property(lambda s:s.obj.orig_set)
def expression_element(self):
return self.obj
def _copy_internals(self):
self.obj = self.obj._clone()
def get_children(self, **kwargs):
return self.obj,
def _get_from_objects(self, **modifiers):
return self.obj._get_from_objects(**modifiers)
def _hide_froms(self, **modifiers):
return self.obj._hide_froms(**modifiers)
def _make_proxy(self, selectable, name = None):
if isinstance(self.obj, (Selectable, ColumnElement)):
return self.obj._make_proxy(selectable, name=self.name)
else:
return column(self.name)._make_proxy(selectable=selectable)
class _ColumnClause(ColumnElement):
"""Represents a generic column expression from any textual string.
This includes columns associated with tables, aliases and select
statements, but also any arbitrary text. May or may not be bound
to an underlying ``Selectable``. ``_ColumnClause`` is usually
created publically via the ``column()`` function or the
``literal_column()`` function.
text
the text of the element.
selectable
parent selectable.
type
``TypeEngine`` object which can associate this ``_ColumnClause``
with a type.
is_literal
if True, the ``_ColumnClause`` is assumed to be an exact
expression that will be delivered to the output with no quoting
rules applied regardless of case sensitive settings. the
``literal_column()`` function is usually used to create such a
``_ColumnClause``.
"""
def __init__(self, text, selectable=None, type_=None, _is_oid=False, is_literal=False):
self.key = self.name = text
self.encodedname = isinstance(self.name, unicode) and self.name.encode('ascii', 'backslashreplace') or self.name
self.table = selectable
self.type = sqltypes.to_instance(type_)
self._is_oid = _is_oid
self._distance = 0
self.__label = None
self.is_literal = is_literal
def _clone(self):
# ColumnClause is immutable
return self
def _get_label(self):
"""Generate a 'label' for this column.
The label is a product of the parent table name and column
name, and is treated as a unique identifier of this ``Column``
across all ``Tables`` and derived selectables for a particular
metadata collection.
"""
# for a "literal" column, we've no idea what the text is
# therefore no 'label' can be automatically generated
if self.is_literal:
return None
if self.__label is None:
if self.table is not None and self.table.named_with_column():
self.__label = self.table.name + "_" + self.name
counter = 1
while self.__label in self.table.c:
self.__label = self.__label + "_%d" % counter
counter += 1
else:
self.__label = self.name
return self.__label
is_labeled = property(lambda self:self.name != list(self.orig_set)[0].name)
_label = property(_get_label)
def label(self, name):
# if going off the "__label" property and its None, we have
# no label; return self
if name is None:
return self
else:
return super(_ColumnClause, self).label(name)
def _get_from_objects(self, **modifiers):
if self.table is not None:
return [self.table]
else:
return []
def _bind_param(self, obj):
return _BindParamClause(self._label, obj, shortname=self.name, type_=self.type, unique=True)
def _make_proxy(self, selectable, name = None):
# propigate the "is_literal" flag only if we are keeping our name,
# otherwise its considered to be a label
is_literal = self.is_literal and (name is None or name == self.name)
c = _ColumnClause(name or self.name, selectable=selectable, _is_oid=self._is_oid, type_=self.type, is_literal=is_literal)
c.orig_set = self.orig_set
c._distance = self._distance + 1
if not self._is_oid:
selectable.columns[c.name] = c
return c
def _compare_type(self, obj):
return self.type
class TableClause(FromClause):
"""Represents a "table" construct.
Note that this represents tables only as another syntactical
construct within SQL expressions; it does not provide schema-level
functionality.
"""
def __init__(self, name, *columns):
super(TableClause, self).__init__(name)
self.name = self.fullname = name
self.encodedname = self.name.encode('ascii', 'backslashreplace')
self.oid_column = _ColumnClause('oid', self, _is_oid=True)
self._export_columns(columns)
def _clone(self):
# TableClause is immutable
return self
def named_with_column(self):
return True
def append_column(self, c):
self._columns[c.name] = c
c.table = self
def _proxy_column(self, c):
self.append_column(c)
return c
def _orig_columns(self):
try:
return self._orig_cols
except AttributeError:
self._orig_cols= {}
for c in self.columns:
for ci in c.orig_set:
self._orig_cols[ci] = c
return self._orig_cols
original_columns = property(_orig_columns)
def get_children(self, column_collections=True, **kwargs):
if column_collections:
return [c for c in self.c]
else:
return []
def _exportable_columns(self):
raise NotImplementedError()
def count(self, whereclause=None, **params):
if self.primary_key:
col = list(self.primary_key)[0]
else:
col = list(self.columns)[0]
return select([func.count(col).label('tbl_row_count')], whereclause, from_obj=[self], **params)
def join(self, right, *args, **kwargs):
return Join(self, right, *args, **kwargs)
def outerjoin(self, right, *args, **kwargs):
return Join(self, right, isouter = True, *args, **kwargs)
def alias(self, name=None):
return Alias(self, name)
def select(self, whereclause = None, **params):
return select([self], whereclause, **params)
def insert(self, values=None, inline=False, **kwargs):
return insert(self, values=values, inline=inline, **kwargs)
def update(self, whereclause=None, values=None, inline=False, **kwargs):
return update(self, whereclause=whereclause, values=values, inline=inline, **kwargs)
def delete(self, whereclause=None):
return delete(self, whereclause)
def _get_from_objects(self, **modifiers):
return [self]
class _SelectBaseMixin(object):
"""Base class for ``Select`` and ``CompoundSelects``."""
def __init__(self, use_labels=False, for_update=False, limit=None, offset=None, order_by=None, group_by=None, bind=None):
self.use_labels = use_labels
self.for_update = for_update
self._limit = limit
self._offset = offset
self._bind = bind
self.append_order_by(*util.to_list(order_by, []))
self.append_group_by(*util.to_list(group_by, []))
def as_scalar(self):
"""return a 'scalar' representation of this selectable, which can be used
as a column expression.
Typically, a select statement which has only one column in its columns clause
is eligible to be used as a scalar expression.
The returned object is an instance of [sqlalchemy.sql.expression#_ScalarSelect].
"""
return _ScalarSelect(self)
def apply_labels(self):
"""set the 'labels' flag on this selectable.
This will result in column expressions being generated using labels against their table
name, such as "SELECT somecolumn AS tablename_somecolumn". This allows selectables which
contain multiple FROM clauses to produce a unique set of column names regardless of name conflicts
among the individual FROM clauses.
"""
s = self._generate()
s.use_labels = True
return s
def label(self, name):
"""return a 'scalar' representation of this selectable, embedded as a subquery
with a label.
See also ``as_scalar()``.
"""
return self.as_scalar().label(name)
def supports_execution(self):
"""part of the ClauseElement contract; returns ``True`` in all cases for this class."""
return True
def _generate(self):
s = self._clone()
s._clone_from_clause()
return s
def limit(self, limit):
"""return a new selectable with the given LIMIT criterion applied."""
s = self._generate()
s._limit = limit
return s
def offset(self, offset):
"""return a new selectable with the given OFFSET criterion applied."""
s = self._generate()
s._offset = offset
return s
def order_by(self, *clauses):
"""return a new selectable with the given list of ORDER BY criterion applied.
The criterion will be appended to any pre-existing ORDER BY criterion.
"""
s = self._generate()
s.append_order_by(*clauses)
return s
def group_by(self, *clauses):
"""return a new selectable with the given list of GROUP BY criterion applied.
The criterion will be appended to any pre-existing GROUP BY criterion.
"""
s = self._generate()
s.append_group_by(*clauses)
return s
def append_order_by(self, *clauses):
"""Append the given ORDER BY criterion applied to this selectable.
The criterion will be appended to any pre-existing ORDER BY criterion.
"""
if clauses == [None]:
self._order_by_clause = ClauseList()
else:
if getattr(self, '_order_by_clause', None):
clauses = list(self._order_by_clause) + list(clauses)
self._order_by_clause = ClauseList(*clauses)
def append_group_by(self, *clauses):
"""Append the given GROUP BY criterion applied to this selectable.
The criterion will be appended to any pre-existing GROUP BY criterion.
"""
if clauses == [None]:
self._group_by_clause = ClauseList()
else:
if getattr(self, '_group_by_clause', None):
clauses = list(self._group_by_clause) + list(clauses)
self._group_by_clause = ClauseList(*clauses)
def select(self, whereclauses = None, **params):
"""return a SELECT of this selectable.
This has the effect of embeddeding this select into a subquery that is selected
from.
"""
return select([self], whereclauses, **params)
def _get_from_objects(self, is_where=False, **modifiers):
if is_where:
return []
else:
return [self]
class _ScalarSelect(_Grouping):
__visit_name__ = 'grouping'
def __init__(self, elem):
super(_ScalarSelect, self).__init__(elem)
self.type = list(elem.inner_columns)[0].type
def _no_cols(self):
raise exceptions.InvalidRequestError("Scalar Select expression has no columns; use this object directly within a column-level expression.")
c = property(_no_cols)
columns = c
def self_group(self, **kwargs):
return self
def _make_proxy(self, selectable, name):
return list(self.inner_columns)[0]._make_proxy(selectable, name)
def _get_from_objects(self, **modifiers):
return []
class CompoundSelect(_SelectBaseMixin, FromClause):
def __init__(self, keyword, *selects, **kwargs):
self._should_correlate = kwargs.pop('correlate', False)
self.keyword = keyword
self.selects = []
# some DBs do not like ORDER BY in the inner queries of a UNION, etc.
for n, s in enumerate(selects):
if s._order_by_clause:
s = s.order_by(None)
# unions group from left to right, so don't group first select
if n:
self.selects.append(s.self_group(self))
else:
self.selects.append(s)
self._col_map = {}
self.oid_column = self.selects[0].oid_column
_SelectBaseMixin.__init__(self, **kwargs)
name = property(lambda s:s.keyword + " statement")
def self_group(self, against=None):
return _FromGrouping(self)
def _exportable_columns(self):
for s in self.selects:
for c in s.c:
yield c
def _proxy_column(self, column):
if self.use_labels:
col = column._make_proxy(self, name=column._label)
else:
col = column._make_proxy(self)
try:
colset = self._col_map[col.name]
except KeyError:
colset = util.Set()
self._col_map[col.name] = colset
[colset.add(c) for c in col.orig_set]
col.orig_set = colset
return col
def _copy_internals(self):
self._clone_from_clause()
self._col_map = {}
self.selects = [s._clone() for s in self.selects]
for attr in ('_order_by_clause', '_group_by_clause'):
if getattr(self, attr) is not None:
setattr(self, attr, getattr(self, attr)._clone())
def get_children(self, column_collections=True, **kwargs):
return (column_collections and list(self.c) or []) + \
[self._order_by_clause, self._group_by_clause] + list(self.selects)
def _table_iterator(self):
for s in self.selects:
for t in s._table_iterator():
yield t
def _find_engine(self):
for s in self.selects:
e = s._find_engine()
if e:
return e
else:
return None
class Select(_SelectBaseMixin, FromClause):
"""Represents a ``SELECT`` statement.
Select statements support appendable clauses, as well as the
ability to execute themselves and return a result set.
"""
def __init__(self, columns, whereclause=None, from_obj=None, distinct=False, having=None, correlate=True, prefixes=None, **kwargs):
"""Construct a Select object.
The public constructor for Select is the
[sqlalchemy.sql.expression#select()] function; see that function for
argument descriptions.
Additional generative and mutator methods are available on the
[sqlalchemy.sql.expression#_SelectBaseMixin] superclass.
"""
self._should_correlate = correlate
self._distinct = distinct
# NOTE: the _generate()
# operation creates a *shallow* copy of the object, so append_XXX() methods,
# usually called via a generative method, create a copy of each collection
# by default
self._raw_columns = []
self.__correlate = util.Set()
self._froms = util.OrderedSet()
self._whereclause = None
self._having = None
self._prefixes = []
if columns is not None:
for c in columns:
self.append_column(c, _copy_collection=False)
if from_obj is not None:
for f in from_obj:
self.append_from(f, _copy_collection=False)
if whereclause is not None:
self.append_whereclause(whereclause)
if having is not None:
self.append_having(having)
if prefixes is not None:
for p in prefixes:
self.append_prefix(p, _copy_collection=False)
_SelectBaseMixin.__init__(self, **kwargs)
def _get_display_froms(self, existing_froms=None):
"""Return the full list of 'from' clauses to be displayed.
Takes into account a set of existing froms which may be
rendered in the FROM clause of enclosing selects; this Select
may want to leave those absent if it is automatically
correlating.
"""
froms = util.OrderedSet()
hide_froms = util.Set()
for col in self._raw_columns:
for f in col._hide_froms():
hide_froms.add(f)
for f in col._get_from_objects():
froms.add(f)
if self._whereclause is not None:
for f in self._whereclause._get_from_objects(is_where=True):
froms.add(f)
for elem in self._froms:
froms.add(elem)
for f in elem._get_from_objects():
froms.add(f)
for elem in froms:
for f in elem._hide_froms():
hide_froms.add(f)
froms = froms.difference(hide_froms)
if len(froms) > 1:
corr = self.__correlate
if self._should_correlate and existing_froms is not None:
corr = existing_froms.union(corr)
f = froms.difference(corr)
if len(f) == 0:
raise exceptions.InvalidRequestError("Select statement '%s' is overcorrelated; returned no 'from' clauses" % str(self.__dont_correlate()))
return f
else:
return froms
froms = property(_get_display_froms, doc="""Return a list of all FromClause elements which will be applied to the FROM clause of the resulting statement.""")
name = property(lambda self:"Select statement", doc="""Placeholder 'name' attribute to meet the FromClause interface.""")
def locate_all_froms(self):
"""return a Set of all FromClause elements referenced by this Select.
This set is a superset of that returned by the ``froms`` property, which
is specifically for those FromClause elements that would actually be rendered.
"""
froms = util.Set()
for col in self._raw_columns:
for f in col._get_from_objects():
froms.add(f)
if self._whereclause is not None:
for f in self._whereclause._get_from_objects(is_where=True):
froms.add(f)
for elem in self._froms:
froms.add(elem)
for f in elem._get_from_objects():
froms.add(f)
return froms
def _get_inner_columns(self):
for c in self._raw_columns:
if isinstance(c, Selectable):
for co in c.columns:
yield co
else:
yield c
inner_columns = property(_get_inner_columns, doc="""a collection of all ColumnElement expressions which would be rendered into the columns clause of the resulting SELECT statement.""")
def _copy_internals(self):
self._clone_from_clause()
self._raw_columns = [c._clone() for c in self._raw_columns]
self._recorrelate_froms([(f, f._clone()) for f in self._froms])
for attr in ('_whereclause', '_having', '_order_by_clause', '_group_by_clause'):
if getattr(self, attr) is not None:
setattr(self, attr, getattr(self, attr)._clone())
def get_children(self, column_collections=True, **kwargs):
"""return child elements as per the ClauseElement specification."""
return (column_collections and list(self.columns) or []) + \
list(self.locate_all_froms()) + \
[x for x in (self._whereclause, self._having, self._order_by_clause, self._group_by_clause) if x is not None]
def _recorrelate_froms(self, froms):
newcorrelate = util.Set()
newfroms = util.Set()
oldfroms = util.Set(self._froms)
for old, new in froms:
if old in self.__correlate:
newcorrelate.add(new)
self.__correlate.remove(old)
if old in oldfroms:
newfroms.add(new)
oldfroms.remove(old)
self.__correlate = self.__correlate.union(newcorrelate)
self._froms = [f for f in oldfroms.union(newfroms)]
def column(self, column):
"""return a new select() construct with the given column expression added to its columns clause."""
s = self._generate()
s.append_column(column)
return s
def where(self, whereclause):
"""return a new select() construct with the given expression added to its WHERE clause, joined
to the existing clause via AND, if any."""
s = self._generate()
s.append_whereclause(whereclause)
return s
def having(self, having):
"""return a new select() construct with the given expression added to its HAVING clause, joined
to the existing clause via AND, if any."""
s = self._generate()
s.append_having(having)
return s
def distinct(self):
"""return a new select() construct which will apply DISTINCT to its columns clause."""
s = self._generate()
s._distinct = True
return s
def prefix_with(self, clause):
"""return a new select() construct which will apply the given expression to the start of its
columns clause, not using any commas."""
s = self._generate()
s.append_prefix(clause)
return s
def select_from(self, fromclause):
"""return a new select() construct with the given FROM expression applied to its list of
FROM objects."""
s = self._generate()
s.append_from(fromclause)
return s
def __dont_correlate(self):
s = self._generate()
s._should_correlate = False
return s
def correlate(self, fromclause):
"""return a new select() construct which will correlate the given FROM clause to that
of an enclosing select(), if a match is found.
By "match", the given fromclause must be present in this select's list of FROM objects
and also present in an enclosing select's list of FROM objects.
Calling this method turns off the select's default behavior of "auto-correlation". Normally,
select() auto-correlates all of its FROM clauses to those of an embedded select when
compiled.
If the fromclause is None, the select() will not correlate to anything.
"""
s = self._generate()
s._should_correlate=False
if fromclause is None:
s.__correlate = util.Set()
else:
s.append_correlation(fromclause)
return s
def append_correlation(self, fromclause, _copy_collection=True):
"""append the given correlation expression to this select() construct."""
if not _copy_collection:
self.__correlate.add(fromclause)
else:
self.__correlate = util.Set(list(self.__correlate) + [fromclause])
def append_column(self, column, _copy_collection=True):
"""append the given column expression to the columns clause of this select() construct."""
column = _literal_as_column(column)
if isinstance(column, _ScalarSelect):
column = column.self_group(against=operators.comma_op)
if not _copy_collection:
self._raw_columns.append(column)
else:
self._raw_columns = self._raw_columns + [column]
def append_prefix(self, clause, _copy_collection=True):
"""append the given columns clause prefix expression to this select() construct."""
clause = _literal_as_text(clause)
if not _copy_collection:
self._prefixes.append(clause)
else:
self._prefixes = self._prefixes + [clause]
def append_whereclause(self, whereclause):
"""append the given expression to this select() construct's WHERE criterion.
The expression will be joined to existing WHERE criterion via AND.
"""
if self._whereclause is not None:
self._whereclause = and_(self._whereclause, _literal_as_text(whereclause))
else:
self._whereclause = _literal_as_text(whereclause)
def append_having(self, having):
"""append the given expression to this select() construct's HAVING criterion.
The expression will be joined to existing HAVING criterion via AND.
"""
if self._having is not None:
self._having = and_(self._having, _literal_as_text(having))
else:
self._having = _literal_as_text(having)
def append_from(self, fromclause, _copy_collection=True):
"""append the given FromClause expression to this select() construct's FROM clause."""
if _is_literal(fromclause):
fromclause = FromClause(fromclause)
if not _copy_collection:
self._froms.add(fromclause)
else:
self._froms = util.Set(list(self._froms) + [fromclause])
def _exportable_columns(self):
return [c for c in self._raw_columns if isinstance(c, (Selectable, ColumnElement))]
def _proxy_column(self, column):
if self.use_labels:
return column._make_proxy(self, name=column._label)
else:
return column._make_proxy(self)
def self_group(self, against=None):
"""return a 'grouping' construct as per the ClauseElement specification.
This produces an element that can be embedded in an expression. Note that
this method is called automatically as needed when constructing expressions.
"""
if isinstance(against, CompoundSelect):
return self
return _FromGrouping(self)
def _locate_oid_column(self):
for f in self.locate_all_froms():
if f is self:
# we might be in our own _froms list if a column with
# us as the parent is attached, which includes textual
# columns.
continue
oid = f.oid_column
if oid is not None:
return oid
else:
return None
oid_column = property(_locate_oid_column, doc="""return the 'oid' column, if any, for this select statement.
This is part of the FromClause contract. The column will usually be the 'oid' column of the first ``Table``
located within the from clause of this select().
""")
def union(self, other, **kwargs):
"""return a SQL UNION of this select() construct against the given selectable."""
return union(self, other, **kwargs)
def union_all(self, other, **kwargs):
"""return a SQL UNION ALL of this select() construct against the given selectable."""
return union_all(self, other, **kwargs)
def except_(self, other, **kwargs):
"""return a SQL EXCEPT of this select() construct against the given selectable."""
return except_(self, other, **kwargs)
def except_all(self, other, **kwargs):
"""return a SQL EXCEPT ALL of this select() construct against the given selectable."""
return except_all(self, other, **kwargs)
def intersect(self, other, **kwargs):
"""return a SQL INTERSECT of this select() construct against the given selectable."""
return intersect(self, other, **kwargs)
def intersect_all(self, other, **kwargs):
"""return a SQL INTERSECT ALL of this select() construct against the given selectable."""
return intersect_all(self, other, **kwargs)
def _table_iterator(self):
for t in visitors.NoColumnVisitor().iterate(self):
if isinstance(t, TableClause):
yield t
def _find_engine(self):
"""Try to return a Engine, either explicitly set in this
object, or searched within the from clauses for one.
"""
if self._bind is not None:
return self._bind
for f in self._froms:
if f is self:
continue
e = f.bind
if e is not None:
self._bind = e
return e
# look through the columns (largely synomous with looking
# through the FROMs except in the case of _CalculatedClause/_Function)
for c in self._exportable_columns():
if getattr(c, 'table', None) is self:
continue
e = c.bind
if e is not None:
self._bind = e
return e
return None
class _UpdateBase(ClauseElement):
"""Form the base for ``INSERT``, ``UPDATE``, and ``DELETE`` statements."""
def supports_execution(self):
return True
def _table_iterator(self):
return iter([self.table])
def _process_colparams(self, parameters):
if parameters is None:
return None
if isinstance(parameters, (list, tuple)):
pp = {}
for i, c in enumerate(self.table.c):
pp[c.key] = parameters[i]
return pp
else:
return parameters
def _find_engine(self):
return self.table.bind
class Insert(_UpdateBase):
def __init__(self, table, values=None, inline=False, **kwargs):
self.table = table
self.select = None
self.inline=inline
self.parameters = self._process_colparams(values)
self.kwargs = kwargs
def get_children(self, **kwargs):
if self.select is not None:
return self.select,
else:
return ()
def _copy_internals(self):
self.parameters = self.parameters.copy()
def values(self, v):
if len(v) == 0:
return self
u = self._clone()
if u.parameters is None:
u.parameters = u._process_colparams(v)
else:
u.parameters = self.parameters.copy()
u.parameters.update(u._process_colparams(v))
return u
class Update(_UpdateBase):
def __init__(self, table, whereclause, values=None, inline=False, **kwargs):
self.table = table
self._whereclause = whereclause
self.inline = inline
self.parameters = self._process_colparams(values)
self.kwargs = kwargs
def get_children(self, **kwargs):
if self._whereclause is not None:
return self._whereclause,
else:
return ()
def _copy_internals(self):
self._whereclause = self._whereclause._clone()
self.parameters = self.parameters.copy()
def values(self, v):
if len(v) == 0:
return self
u = self._clone()
if u.parameters is None:
u.parameters = u._process_colparams(v)
else:
u.parameters = self.parameters.copy()
u.parameters.update(u._process_colparams(v))
return u
class Delete(_UpdateBase):
def __init__(self, table, whereclause):
self.table = table
self._whereclause = whereclause
def get_children(self, **kwargs):
if self._whereclause is not None:
return self._whereclause,
else:
return ()
def _copy_internals(self):
self._whereclause = self._whereclause._clone()
class _IdentifiedClause(ClauseElement):
def __init__(self, ident):
self.ident = ident
def supports_execution(self):
return True
class SavepointClause(_IdentifiedClause):
pass
class RollbackToSavepointClause(_IdentifiedClause):
pass
class ReleaseSavepointClause(_IdentifiedClause):
pass
Reference in New Issue View Git Blame Copy Permalink