selectable.py

SQLAlchemy. 经典的Python ORM框架。学习必看。

"""tests that various From objects properly export their columns, as well as
useable primary keys and foreign keys.  Full relational algebra depends on
every selectable unit behaving nicely with others.."""

import testenv; testenv.configure_for_tests()
from sqlalchemy import *
from testlib import *
from sqlalchemy.sql import util as sql_util

metadata = MetaData()
table = Table('table1', metadata,
    Column('col1', Integer, primary_key=True),
    Column('col2', String(20)),
    Column('col3', Integer),
    Column('colx', Integer),

)

table2 = Table('table2', metadata,
    Column('col1', Integer, primary_key=True),
    Column('col2', Integer, ForeignKey('table1.col1')),
    Column('col3', String(20)),
    Column('coly', Integer),
)

class SelectableTest(TestBase, AssertsExecutionResults):
    def testdistance(self):
        # same column three times
        s = select([table.c.col1.label('c2'), table.c.col1, table.c.col1.label('c1')])

        # didnt do this yet...col.label().make_proxy() has same "distance" as col.make_proxy() so far
        #assert s.corresponding_column(table.c.col1) is s.c.col1
        assert s.corresponding_column(s.c.col1) is s.c.col1
        assert s.corresponding_column(s.c.c1) is s.c.c1

    def testjoinagainstself(self):
        jj = select([table.c.col1.label('bar_col1')])
        jjj = join(table, jj, table.c.col1==jj.c.bar_col1)

        # test column directly agaisnt itself
        assert jjj.corresponding_column(jjj.c.table1_col1) is jjj.c.table1_col1

        assert jjj.corresponding_column(jj.c.bar_col1) is jjj.c.bar_col1

        # test alias of the join, targets the column with the least
        # "distance" between the requested column and the returned column
        # (i.e. there is less indirection between j2.c.table1_col1 and table.c.col1, than
        # there is from j2.c.bar_col1 to table.c.col1)
        j2 = jjj.alias('foo')
        assert j2.corresponding_column(table.c.col1) is j2.c.table1_col1

    def testselectontable(self):
        sel = select([table, table2], use_labels=True)
        assert sel.corresponding_column(table.c.col1) is sel.c.table1_col1
        assert sel.corresponding_column(table.c.col1, require_embedded=True) is sel.c.table1_col1
        assert table.corresponding_column(sel.c.table1_col1) is table.c.col1
        assert table.corresponding_column(sel.c.table1_col1, require_embedded=True) is None

    def testjoinagainstjoin(self):
        j  = outerjoin(table, table2, table.c.col1==table2.c.col2)
        jj = select([ table.c.col1.label('bar_col1')],from_obj=[j]).alias('foo')
        jjj = join(table, jj, table.c.col1==jj.c.bar_col1)
        assert jjj.corresponding_column(jjj.c.table1_col1) is jjj.c.table1_col1

        j2 = jjj.alias('foo')
        print j2.corresponding_column(jjj.c.table1_col1)
        assert j2.corresponding_column(jjj.c.table1_col1) is j2.c.table1_col1

        assert jjj.corresponding_column(jj.c.bar_col1) is jj.c.bar_col1

    def testtablealias(self):
        a = table.alias('a')

        j = join(a, table2)

        criterion = a.c.col1 == table2.c.col2
        self.assert_(criterion.compare(j.onclause))

    def testunion(self):
        # tests that we can correspond a column in a Select statement with a certain Table, against
        # a column in a Union where one of its underlying Selects matches to that same Table
        u = select([table.c.col1, table.c.col2, table.c.col3, table.c.colx, null().label('coly')]).union(
                select([table2.c.col1, table2.c.col2, table2.c.col3, null().label('colx'), table2.c.coly])
            )
        s1 = table.select(use_labels=True)
        s2 = table2.select(use_labels=True)
        print ["%d %s" % (id(c),c.key) for c in u.c]
        c = u.corresponding_column(s1.c.table1_col2)
        print "%d %s" % (id(c), c.key)
        print id(u.corresponding_column(s1.c.table1_col2).table)
        print id(u.c.col2.table)
        assert u.corresponding_column(s1.c.table1_col2) is u.c.col2
        assert u.corresponding_column(s2.c.table2_col2) is u.c.col2

    def test_singular_union(self):
        u = union(select([table.c.col1, table.c.col2, table.c.col3]), select([table.c.col1, table.c.col2, table.c.col3]))
        assert u.oid_column is not None

        u = union(select([table.c.col1, table.c.col2, table.c.col3]))
        assert u.oid_column
        assert u.c.col1
        assert u.c.col2
        assert u.c.col3
        
    def testaliasunion(self):
        # same as testunion, except its an alias of the union
        u = select([table.c.col1, table.c.col2, table.c.col3, table.c.colx, null().label('coly')]).union(
                select([table2.c.col1, table2.c.col2, table2.c.col3, null().label('colx'), table2.c.coly])
            ).alias('analias')
        s1 = table.select(use_labels=True)
        s2 = table2.select(use_labels=True)
        assert u.corresponding_column(s1.c.table1_col2) is u.c.col2
        assert u.corresponding_column(s2.c.table2_col2) is u.c.col2
        assert u.corresponding_column(s2.c.table2_coly) is u.c.coly
        assert s2.corresponding_column(u.c.coly) is s2.c.table2_coly

    def testselectunion(self):
        # like testaliasunion, but off a Select off the union.
        u = select([table.c.col1, table.c.col2, table.c.col3, table.c.colx, null().label('coly')]).union(
                select([table2.c.col1, table2.c.col2, table2.c.col3, null().label('colx'), table2.c.coly])
            ).alias('analias')
        s = select([u])
        s1 = table.select(use_labels=True)
        s2 = table2.select(use_labels=True)
        assert s.corresponding_column(s1.c.table1_col2) is s.c.col2
        assert s.corresponding_column(s2.c.table2_col2) is s.c.col2

    def testunionagainstjoin(self):
        # same as testunion, except its an alias of the union
        u = select([table.c.col1, table.c.col2, table.c.col3, table.c.colx, null().label('coly')]).union(
                select([table2.c.col1, table2.c.col2, table2.c.col3, null().label('colx'), table2.c.coly])
            ).alias('analias')
        j1 = table.join(table2)
        assert u.corresponding_column(j1.c.table1_colx) is u.c.colx
        assert j1.corresponding_column(u.c.colx) is j1.c.table1_colx

    def testjoin(self):
        a = join(table, table2)
        print str(a.select(use_labels=True))
        b = table2.alias('b')
        j = join(a, b)
        print str(j)
        criterion = a.c.table1_col1 == b.c.col2
        self.assert_(criterion.compare(j.onclause))

    def testselectalias(self):
        a = table.select().alias('a')
        print str(a.select())
        j = join(a, table2)

        criterion = a.c.col1 == table2.c.col2
        print criterion
        print j.onclause
        self.assert_(criterion.compare(j.onclause))

    def testselectlabels(self):
        a = table.select(use_labels=True)
        print str(a.select())
        j = join(a, table2)

        criterion = a.c.table1_col1 == table2.c.col2
        print
        print str(j)
        self.assert_(criterion.compare(j.onclause))

    def testcolumnlabels(self):
        a = select([table.c.col1.label('acol1'), table.c.col2.label('acol2'), table.c.col3.label('acol3')])
        print str(a)
        print [c for c in a.columns]
        print str(a.select())
        j = join(a, table2)
        criterion = a.c.acol1 == table2.c.col2
        print str(j)
        self.assert_(criterion.compare(j.onclause))

    def testselectaliaslabels(self):
        a = table2.select(use_labels=True).alias('a')
        print str(a.select())
        j = join(a, table)

        criterion =  table.c.col1 == a.c.table2_col2
        print str(criterion)
        print str(j.onclause)
        self.assert_(criterion.compare(j.onclause))

    def testtablejoinedtoselectoftable(self):
        metadata = MetaData()
        a = Table('a', metadata,
            Column('id', Integer, primary_key=True))
        b = Table('b', metadata,
            Column('id', Integer, primary_key=True),
            Column('aid', Integer, ForeignKey('a.id')),
            )

        j1 = a.outerjoin(b)
        j2 = select([a.c.id.label('aid')]).alias('bar')

        j3 = a.join(j2, j2.c.aid==a.c.id)

        j4 = select([j3]).alias('foo')
        print j4
        print j4.corresponding_column(j2.c.aid)
        print j4.c.aid
        assert j4.corresponding_column(j2.c.aid) is j4.c.aid
        assert j4.corresponding_column(a.c.id) is j4.c.id

    @testing.emits_warning('.*replaced by another column with the same key')
    def test_oid(self):
        # the oid column of a selectable currently proxies all
        # oid columns found within.
        s = table.select()
        s2 = table2.select()
        s3 = select([s, s2])
        assert s3.corresponding_column(table.oid_column) is s3.oid_column
        assert s3.corresponding_column(table2.oid_column) is s3.oid_column
        assert s3.corresponding_column(s.oid_column) is s3.oid_column
        assert s3.corresponding_column(s2.oid_column) is s3.oid_column

        u = s.union(s2)
        assert u.corresponding_column(table.oid_column) is u.oid_column
        assert u.corresponding_column(table2.oid_column) is u.oid_column
        assert u.corresponding_column(s.oid_column) is u.oid_column
        assert u.corresponding_column(s2.oid_column) is u.oid_column
    
class PrimaryKeyTest(TestBase, AssertsExecutionResults):
    def test_join_pk_collapse_implicit(self):
        """test that redundant columns in a join get 'collapsed' into a minimal primary key,
        which is the root column along a chain of foreign key relationships."""

        meta = MetaData()