mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-07 17:31:24 -04:00
Jason Kirtland
177d30cc01
- Deprecated BoundMetaData- use MetaData instead - Removed DMD and BMD from documentation
104 lines
3.6 KiB
Python
104 lines
3.6 KiB
Python
from sqlalchemy import *
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import sets
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# this example illustrates a polymorphic load of two classes, where each class has a very
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# different set of properties
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metadata = MetaData('sqlite://', echo=True)
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# a table to store companies
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companies = Table('companies', metadata,
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Column('company_id', Integer, primary_key=True),
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Column('name', String(50)))
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# we will define an inheritance relationship between the table "people" and "engineers",
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# and a second inheritance relationship between the table "people" and "managers"
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people = Table('people', metadata,
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Column('person_id', Integer, primary_key=True),
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Column('company_id', Integer, ForeignKey('companies.company_id')),
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Column('name', String(50)),
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Column('type', String(30)))
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engineers = Table('engineers', metadata,
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Column('person_id', Integer, ForeignKey('people.person_id'), primary_key=True),
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Column('status', String(30)),
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Column('engineer_name', String(50)),
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Column('primary_language', String(50)),
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)
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managers = Table('managers', metadata,
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Column('person_id', Integer, ForeignKey('people.person_id'), primary_key=True),
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Column('status', String(30)),
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Column('manager_name', String(50))
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)
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metadata.create_all()
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# create our classes. The Engineer and Manager classes extend from Person.
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class Person(object):
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def __init__(self, **kwargs):
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for key, value in kwargs.iteritems():
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setattr(self, key, value)
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def __repr__(self):
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return "Ordinary person %s" % self.name
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class Engineer(Person):
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def __repr__(self):
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return "Engineer %s, status %s, engineer_name %s, primary_language %s" % (self.name, self.status, self.engineer_name, self.primary_language)
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class Manager(Person):
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def __repr__(self):
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return "Manager %s, status %s, manager_name %s" % (self.name, self.status, self.manager_name)
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class Company(object):
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def __init__(self, **kwargs):
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for key, value in kwargs.iteritems():
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setattr(self, key, value)
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def __repr__(self):
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return "Company %s" % self.name
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person_join = people.outerjoin(engineers).outerjoin(managers)
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person_mapper = mapper(Person, people, select_table=person_join,polymorphic_on=people.c.type, polymorphic_identity='person')
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mapper(Engineer, engineers, inherits=person_mapper, polymorphic_identity='engineer')
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mapper(Manager, managers, inherits=person_mapper, polymorphic_identity='manager')
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mapper(Company, companies, properties={
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'employees': relation(Person, lazy=False, private=True, backref='company')
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})
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session = create_session(echo_uow=False)
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c = Company(name='company1')
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c.employees.append(Manager(name='pointy haired boss', status='AAB', manager_name='manager1'))
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c.employees.append(Engineer(name='dilbert', status='BBA', engineer_name='engineer1', primary_language='java'))
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c.employees.append(Person(name='joesmith', status='HHH'))
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c.employees.append(Engineer(name='wally', status='CGG', engineer_name='engineer2', primary_language='python'))
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c.employees.append(Manager(name='jsmith', status='ABA', manager_name='manager2'))
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session.save(c)
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print session.new
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session.flush()
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session.clear()
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c = session.query(Company).get(1)
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for e in c.employees:
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print e, e._instance_key, e.company
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assert sets.Set([e.name for e in c.employees]) == sets.Set(['pointy haired boss', 'dilbert', 'joesmith', 'wally', 'jsmith'])
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print "\n"
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dilbert = session.query(Person).get_by(name='dilbert')
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dilbert2 = session.query(Engineer).get_by(name='dilbert')
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assert dilbert is dilbert2
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dilbert.engineer_name = 'hes dibert!'
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session.flush()
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session.clear()
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c = session.query(Company).get(1)
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for e in c.employees:
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print e, e._instance_key
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session.delete(c)
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session.flush()
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metadata.drop_all()
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