lazytest1.py

SQLAlchemy. 经典的Python ORM框架。学习必看。

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

class LazyTest(TestBase, AssertsExecutionResults):
    def setUpAll(self):
        global info_table, data_table, rel_table, metadata
        metadata = MetaData(testing.db)
        info_table = Table('infos', metadata,
                           Column('pk', Integer, primary_key=True),
                           Column('info', String(128)))

        data_table = Table('data', metadata,
                           Column('data_pk', Integer, primary_key=True),
                           Column('info_pk', Integer,
                                  ForeignKey(info_table.c.pk)),
                           Column('timeval', Integer),
                           Column('data_val', String(128)))

        rel_table = Table('rels', metadata,
                          Column('rel_pk', Integer, primary_key=True),
                          Column('info_pk', Integer,
                                 ForeignKey(info_table.c.pk)),
                          Column('start', Integer),
                          Column('finish', Integer))

        metadata.create_all()
        info_table.insert().execute(
            {'pk':1, 'info':'pk_1_info'},
            {'pk':2, 'info':'pk_2_info'},
            {'pk':3, 'info':'pk_3_info'},
            {'pk':4, 'info':'pk_4_info'},
            {'pk':5, 'info':'pk_5_info'})

        rel_table.insert().execute(
            {'rel_pk':1, 'info_pk':1, 'start':10, 'finish':19},
            {'rel_pk':2, 'info_pk':1, 'start':100, 'finish':199},
            {'rel_pk':3, 'info_pk':2, 'start':20, 'finish':29},
            {'rel_pk':4, 'info_pk':3, 'start':13, 'finish':23},
            {'rel_pk':5, 'info_pk':5, 'start':15, 'finish':25})

        data_table.insert().execute(
            {'data_pk':1, 'info_pk':1, 'timeval':11, 'data_val':'11_data'},
            {'data_pk':2, 'info_pk':1, 'timeval':9, 'data_val':'9_data'},
            {'data_pk':3, 'info_pk':1, 'timeval':13, 'data_val':'13_data'},
            {'data_pk':4, 'info_pk':2, 'timeval':23, 'data_val':'23_data'},
            {'data_pk':5, 'info_pk':2, 'timeval':13, 'data_val':'13_data'},
            {'data_pk':6, 'info_pk':1, 'timeval':15, 'data_val':'15_data'})


    def tearDownAll(self):
        metadata.drop_all()

    def testone(self):
        """Tests a lazy load which has multiple join conditions.

        ...including two that are against the same column in the child table.
        """

        class Information(object):
            pass

        class Relation(object):
            pass

        class Data(object):
            pass

        session = create_session()

        mapper(Data, data_table)
        mapper(Relation, rel_table, properties={
            'datas': relation(Data,
                              primaryjoin=and_(
                                rel_table.c.info_pk ==
                                data_table.c.info_pk,
                                data_table.c.timeval >= rel_table.c.start,
                                data_table.c.timeval <= rel_table.c.finish),
                              foreign_keys=[data_table.c.info_pk])})
        mapper(Information, info_table, properties={
            'rels': relation(Relation)
        })

        info = session.query(Information).get(1)
        assert info
        assert len(info.rels) == 2
        assert len(info.rels[0].datas) == 3

if __name__ == "__main__":
    testenv.main()