mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-15 05:07:16 -04:00
Mike Bayer
36e8fe48b2
Added new "post compile parameters" feature. This feature allows a :func:`.bindparam` construct to have its value rendered into the SQL string before being passed to the DBAPI driver, but after the compilation step, using the "literal render" feature of the compiler. The immediate rationale for this feature is to support LIMIT/OFFSET schemes that don't work or perform well as bound parameters handled by the database driver, while still allowing for SQLAlchemy SQL constructs to be cacheable in their compiled form. The immediate targets for the new feature are the "TOP N" clause used by SQL Server (and Sybase) which does not support a bound parameter, as well as the "ROWNUM" and optional "FIRST_ROWS()" schemes used by the Oracle dialect, the former of which has been known to perform better without bound parameters and the latter of which does not support a bound parameter. The feature builds upon the mechanisms first developed to support "expanding" parameters for IN expressions. As part of this feature, the Oracle ``use_binds_for_limits`` feature is turned on unconditionally and this flag is now deprecated. - adds limited support for "unique" bound parameters within a text() construct. - adds an additional int() check within the literal render function of the Integer datatype and tests that non-int values raise ValueError. Fixes: #4808 Change-Id: Iace97d544d1a7351ee07db970c6bc06a19c712c6
301 lines
9.2 KiB
Python
301 lines
9.2 KiB
Python
from sqlalchemy import bindparam
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from sqlalchemy import Column
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from sqlalchemy import exc
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from sqlalchemy import Integer
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from sqlalchemy import MetaData
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from sqlalchemy import select
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from sqlalchemy import Table
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from sqlalchemy import testing
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from sqlalchemy import text
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from sqlalchemy.schema import DDL
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from sqlalchemy.schema import Sequence
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from sqlalchemy.sql import ClauseElement
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from sqlalchemy.sql import coercions
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from sqlalchemy.sql import column
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from sqlalchemy.sql import false
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from sqlalchemy.sql import False_
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from sqlalchemy.sql import literal
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from sqlalchemy.sql import roles
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from sqlalchemy.sql import true
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from sqlalchemy.sql import True_
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from sqlalchemy.sql.coercions import expect
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from sqlalchemy.sql.elements import _truncated_label
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from sqlalchemy.sql.elements import Null
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from sqlalchemy.sql.selectable import FromGrouping
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from sqlalchemy.sql.selectable import SelectStatementGrouping
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from sqlalchemy.testing import assert_raises
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from sqlalchemy.testing import assert_raises_message
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from sqlalchemy.testing import fixtures
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from sqlalchemy.testing import is_
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from sqlalchemy.testing import is_instance_of
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from sqlalchemy.testing import is_true
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m = MetaData()
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t = Table("t", m, Column("q", Integer))
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class NotAThing1(object):
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pass
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not_a_thing1 = NotAThing1()
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class NotAThing2(ClauseElement):
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pass
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not_a_thing2 = NotAThing2()
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class NotAThing3(object):
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def __clause_element__(self):
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return not_a_thing2
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not_a_thing3 = NotAThing3()
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class RoleTest(fixtures.TestBase):
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# TODO: the individual role tests here are incomplete. The functionality
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# of each role is covered by other tests in the sql testing suite however
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# ideally they'd all have direct tests here as well.
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def _test_role_neg_comparisons(self, role):
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impl = coercions._impl_lookup[role]
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role_name = impl.name
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assert_raises_message(
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exc.ArgumentError,
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r"%s expected, got .*NotAThing1" % role_name,
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expect,
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role,
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not_a_thing1,
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)
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assert_raises_message(
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exc.ArgumentError,
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r"%s expected, got .*NotAThing2" % role_name,
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expect,
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role,
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not_a_thing2,
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)
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assert_raises_message(
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exc.ArgumentError,
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r"%s expected, got .*NotAThing3" % role_name,
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expect,
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role,
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not_a_thing3,
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)
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assert_raises_message(
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exc.ArgumentError,
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r"%s expected for argument 'foo'; got .*NotAThing3" % role_name,
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expect,
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role,
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not_a_thing3,
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argname="foo",
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)
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def test_const_expr_role(self):
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t = true()
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is_(expect(roles.ConstExprRole, t), t)
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f = false()
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is_(expect(roles.ConstExprRole, f), f)
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is_instance_of(expect(roles.ConstExprRole, True), True_)
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is_instance_of(expect(roles.ConstExprRole, False), False_)
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is_instance_of(expect(roles.ConstExprRole, None), Null)
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def test_truncated_label_role(self):
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is_instance_of(
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expect(roles.TruncatedLabelRole, "foobar"), _truncated_label
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)
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def test_labeled_column_expr_role(self):
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c = column("q")
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is_true(expect(roles.LabeledColumnExprRole, c).compare(c))
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is_true(
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expect(roles.LabeledColumnExprRole, c.label("foo")).compare(
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c.label("foo")
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)
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)
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is_true(
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expect(
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roles.LabeledColumnExprRole,
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select([column("q")]).scalar_subquery(),
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).compare(select([column("q")]).label(None))
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)
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is_true(
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expect(roles.LabeledColumnExprRole, not_a_thing1).compare(
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literal(not_a_thing1).label(None)
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)
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)
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def test_scalar_select_no_coercion(self):
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# this is also tested in test/sql/test_deprecations.py; when the
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# deprecation is turned to an error, those tests go away, and these
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# will assert the correct exception plus informative error message.
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assert_raises_message(
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exc.SADeprecationWarning,
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"coercing SELECT object to scalar subquery in a column-expression "
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"context is deprecated",
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expect,
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roles.LabeledColumnExprRole,
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select([column("q")]),
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)
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assert_raises_message(
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exc.SADeprecationWarning,
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"coercing SELECT object to scalar subquery in a column-expression "
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"context is deprecated",
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expect,
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roles.LabeledColumnExprRole,
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select([column("q")]).alias(),
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)
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def test_statement_no_text_coercion(self):
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assert_raises_message(
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exc.ArgumentError,
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r"Textual SQL expression 'select \* from table' should be "
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r"explicitly declared",
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expect,
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roles.StatementRole,
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"select * from table",
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)
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def test_statement_text_coercion(self):
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is_true(
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expect(
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roles.CoerceTextStatementRole, "select * from table"
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).compare(text("select * from table"))
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)
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def test_select_statement_no_text_coercion(self):
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assert_raises_message(
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exc.ArgumentError,
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r"Textual SQL expression 'select \* from table' should be "
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r"explicitly declared",
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expect,
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roles.SelectStatementRole,
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"select * from table",
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)
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def test_select_is_coerced_into_fromclause_w_deprecation(self):
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with testing.expect_deprecated(
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"Implicit coercion of SELECT and textual SELECT "
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"constructs into FROM clauses is deprecated;"
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):
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element = expect(
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roles.FromClauseRole, SelectStatementGrouping(select([t]))
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)
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is_true(
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element.compare(
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SelectStatementGrouping(select([t])).subquery()
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)
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)
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def test_offset_or_limit_role_only_ints_or_clauseelement(self):
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assert_raises(ValueError, select([t]).limit, "some limit")
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assert_raises(ValueError, select([t]).offset, "some offset")
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def test_offset_or_limit_role_clauseelement(self):
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bind = bindparam("x")
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stmt = select([t]).limit(bind)
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is_(stmt._limit_clause, bind)
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stmt = select([t]).offset(bind)
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is_(stmt._offset_clause, bind)
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def test_from_clause_is_not_a_select(self):
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assert_raises_message(
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exc.ArgumentError,
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r"SELECT construct or equivalent text\(\) construct expected,",
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expect,
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roles.SelectStatementRole,
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FromGrouping(t),
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)
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def test_text_as_from_select_statement(self):
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is_true(
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expect(
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roles.SelectStatementRole,
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text("select * from table").columns(t.c.q),
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).compare(text("select * from table").columns(t.c.q))
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)
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def test_statement_coercion_select(self):
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is_true(
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expect(roles.CoerceTextStatementRole, select([t])).compare(
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select([t])
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)
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)
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def test_statement_coercion_ddl(self):
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d1 = DDL("hi")
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is_(expect(roles.CoerceTextStatementRole, d1), d1)
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def test_strict_from_clause_role(self):
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stmt = select([t]).subquery()
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is_true(
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expect(roles.StrictFromClauseRole, stmt).compare(
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select([t]).subquery()
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)
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)
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def test_strict_from_clause_role_disallow_select(self):
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stmt = select([t])
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assert_raises_message(
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exc.ArgumentError,
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r"FROM expression, such as a Table or alias\(\) "
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"object expected, got .*Select",
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expect,
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roles.StrictFromClauseRole,
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stmt,
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)
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def test_anonymized_from_clause_role(self):
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is_true(expect(roles.AnonymizedFromClauseRole, t).compare(t.alias()))
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# note the compare for subquery().alias(), even if it is two
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# plain Alias objects (which it won't be once we introduce the
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# Subquery class), still compares based on alias() being present
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# twice, that is, alias().alias() builds an alias of an alias, rather
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# than just replacing the outer alias.
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is_true(
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expect(
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roles.AnonymizedFromClauseRole, select([t]).subquery()
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).compare(select([t]).subquery().alias())
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)
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def test_statement_coercion_sequence(self):
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s1 = Sequence("hi")
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is_(expect(roles.CoerceTextStatementRole, s1), s1)
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def test_columns_clause_role(self):
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is_(expect(roles.ColumnsClauseRole, t.c.q), t.c.q)
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def test_truncated_label_role_neg(self):
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self._test_role_neg_comparisons(roles.TruncatedLabelRole)
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def test_where_having_role_neg(self):
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self._test_role_neg_comparisons(roles.WhereHavingRole)
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def test_by_of_role_neg(self):
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self._test_role_neg_comparisons(roles.ByOfRole)
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def test_const_expr_role_neg(self):
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self._test_role_neg_comparisons(roles.ConstExprRole)
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def test_columns_clause_role_neg(self):
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self._test_role_neg_comparisons(roles.ColumnsClauseRole)
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