mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-10 02:39:59 -04:00
Mike Bayer
101 lines
3.2 KiB
Python
101 lines
3.2 KiB
Python
from sqlalchemy import MetaData, Table, Column, Integer, String, \
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ForeignKey, create_engine
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from sqlalchemy.orm import mapper, relationship, sessionmaker
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metadata = MetaData()
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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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employees_table = Table('employees', metadata,
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Column('employee_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(20)),
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Column('status', String(20)),
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Column('engineer_name', String(50)),
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Column('primary_language', String(50)),
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Column('manager_name', String(50))
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)
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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, "\
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"primary_language %s" % \
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(self.name, self.status,
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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" % \
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(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_mapper = mapper(Person, employees_table,
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polymorphic_on=employees_table.c.type,
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polymorphic_identity='person')
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manager_mapper = mapper(Manager, inherits=person_mapper,
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polymorphic_identity='manager')
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engineer_mapper = mapper(Engineer, inherits=person_mapper,
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polymorphic_identity='engineer')
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mapper(Company, companies, properties={
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'employees': relationship(Person, lazy=True, backref='company')
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})
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engine = create_engine('sqlite:///', echo=True)
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metadata.create_all(engine)
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session = sessionmaker(engine)()
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c = Company(name='company1')
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c.employees.append(Manager(name='pointy haired boss', status='AAB',
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manager_name='manager1'))
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c.employees.append(Engineer(name='dilbert', status='BBA',
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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',
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engineer_name='engineer2', primary_language='python'
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))
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c.employees.append(Manager(name='jsmith', status='ABA',
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manager_name='manager2'))
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session.add(c)
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session.commit()
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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.company
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print "\n"
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dilbert = session.query(Person).filter_by(name='dilbert').one()
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dilbert2 = session.query(Engineer).filter_by(name='dilbert').one()
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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.expunge_all()
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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
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session.delete(c)
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session.commit()
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