polymorph.py

SQLAlchemy. 经典的Python ORM框架。学习必看。

"""tests basic polymorphic mapper loading/saving, minimal relations"""

import testenv; testenv.configure_for_tests()
import sets
from sqlalchemy import *
from sqlalchemy.orm import *
from testlib import *


class Person(object):
    def __init__(self, **kwargs):
        for key, value in kwargs.iteritems():
            setattr(self, key, value)
    def get_name(self):
        try:
            return getattr(self, 'person_name')
        except AttributeError:
            return getattr(self, 'name')
    def __repr__(self):
        return "Ordinary person %s" % self.get_name()
class Engineer(Person):
    def __repr__(self):
        return "Engineer %s, status %s, engineer_name %s, primary_language %s" % (self.get_name(), self.status, self.engineer_name, self.primary_language)
class Manager(Person):
    def __repr__(self):
        return "Manager %s, status %s, manager_name %s" % (self.get_name(), self.status, self.manager_name)
class Boss(Manager):
    def __repr__(self):
        return "Boss %s, status %s, manager_name %s golf swing %s" % (self.get_name(), self.status, self.manager_name, self.golf_swing)

class Company(object):
    def __init__(self, **kwargs):
        for key, value in kwargs.iteritems():
            setattr(self, key, value)
    def __repr__(self):
        return "Company %s" % self.name

class PolymorphTest(ORMTest):
    def define_tables(self, metadata):
        global companies, people, engineers, managers, boss

        # a table to store companies
        companies = Table('companies', metadata,
           Column('company_id', Integer, Sequence('company_id_seq', optional=True), primary_key=True),
           Column('name', String(50)))

        # we will define an inheritance relationship between the table "people" and "engineers",
        # and a second inheritance relationship between the table "people" and "managers"
        people = Table('people', metadata,
           Column('person_id', Integer, Sequence('person_id_seq', optional=True), primary_key=True),
           Column('company_id', Integer, ForeignKey('companies.company_id')),
           Column('name', String(50)),
           Column('type', String(30)))

        engineers = Table('engineers', metadata,
           Column('person_id', Integer, ForeignKey('people.person_id'), primary_key=True),
           Column('status', String(30)),
           Column('engineer_name', String(50)),
           Column('primary_language', String(50)),
          )

        managers = Table('managers', metadata,
           Column('person_id', Integer, ForeignKey('people.person_id'), primary_key=True),
           Column('status', String(30)),
           Column('manager_name', String(50))
           )

        boss = Table('boss', metadata,
            Column('boss_id', Integer, ForeignKey('managers.person_id'), primary_key=True),
            Column('golf_swing', String(30)),
            )

        metadata.create_all()

class CompileTest(PolymorphTest):
    def testcompile(self):
        person_join = polymorphic_union( {
            'engineer':people.join(engineers),
            'manager':people.join(managers),
            'person':people.select(people.c.type=='person'),
            }, None, 'pjoin')

        person_mapper = mapper(Person, people, select_table=person_join, polymorphic_on=person_join.c.type, polymorphic_identity='person')
        mapper(Engineer, engineers, inherits=person_mapper, polymorphic_identity='engineer')
        mapper(Manager, managers, inherits=person_mapper, polymorphic_identity='manager')

        session = create_session()
        session.save(Manager(name='Tom', status='knows how to manage things'))
        session.save(Engineer(name='Kurt', status='knows how to hack'))
        session.flush()
        print session.query(Engineer).all()

        print session.query(Person).all()

    def testcompile2(self):
        """test that a mapper can reference a property whose mapper inherits from this one."""
        person_join = polymorphic_union( {
            'engineer':people.join(engineers),
            'manager':people.join(managers),
            'person':people.select(people.c.type=='person'),
            }, None, 'pjoin')


        person_mapper = mapper(Person, people, select_table=person_join, polymorphic_on=person_join.c.type,
                    polymorphic_identity='person',
                    properties = dict(managers = relation(Manager, lazy=True))
                )

        mapper(Engineer, engineers, inherits=person_mapper, polymorphic_identity='engineer')
        mapper(Manager, managers, inherits=person_mapper, polymorphic_identity='manager')

        #person_mapper.compile()
        class_mapper(Manager).compile()

class InsertOrderTest(PolymorphTest):
    def test_insert_order(self):
        """test that classes of multiple types mix up mapper inserts
        so that insert order of individual tables is maintained"""
        person_join = polymorphic_union(
            {
                'engineer':people.join(engineers),
                'manager':people.join(managers),
                'person':people.select(people.c.type=='person'),
            }, None, 'pjoin')

        person_mapper = mapper(Person, people, select_table=person_join, polymorphic_on=person_join.c.type, polymorphic_identity='person')

        mapper(Engineer, engineers, inherits=person_mapper, polymorphic_identity='engineer')
        mapper(Manager, managers, inherits=person_mapper, polymorphic_identity='manager')
        mapper(Company, companies, properties={
            'employees': relation(Person,
                                  cascade="all, delete-orphan",
                                  backref='company',
                                  order_by=person_join.c.person_id)
        })

        session = create_session()
        c = Company(name='company1')
        c.employees.append(Manager(status='AAB', manager_name='manager1', name='pointy haired boss'))
        c.employees.append(Engineer(status='BBA', engineer_name='engineer1', primary_language='java', name='dilbert'))
        c.employees.append(Person(status='HHH', name='joesmith'))
        c.employees.append(Engineer(status='CGG', engineer_name='engineer2', primary_language='python', name='wally'))
        c.employees.append(Manager(status='ABA', manager_name='manager2', name='jsmith'))
        session.save(c)
        session.flush()
        session.clear()
        c = session.query(Company).get(c.company_id)
        for e in c.employees:
            print e, e._instance_key, e.company

        assert [e.get_name() for e in c.employees] == ['pointy haired boss', 'dilbert', 'joesmith', 'wally', 'jsmith']

class RelationToSubclassTest(PolymorphTest):
    def testrelationtosubclass(self):
        """test a relation to an inheriting mapper where the relation is to a subclass
        but the join condition is expressed by the parent table.

        also test that backrefs work in this case.

        this test touches upon a lot of the join/foreign key determination code in properties.py
        and creates the need for properties.py to search for conditions individually within
        the mapper's local table as well as the mapper's 'mapped' table, so that relations
        requiring lots of specificity (like self-referential joins) as well as relations requiring
        more generalization (like the example here) both come up with proper results."""

        mapper(Person, people)

        mapper(Engineer, engineers, inherits=Person)
        mapper(Manager, managers, inherits=Person)

        mapper(Company, companies, properties={
            'managers': relation(Manager, lazy=True,backref="company")
        })

        sess = create_session()

        c = Company(name='company1')
        c.managers.append(Manager(status='AAB', manager_name='manager1', name='pointy haired boss'))
        sess.save(c)
        sess.flush()
        sess.clear()

        sess.query(Company).filter_by(company_id=c.company_id).one()
        assert sets.Set([e.get_name() for e in c.managers]) == sets.Set(['pointy haired boss'])