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from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.testing import fixtures
from sqlalchemy import testing
from sqlalchemy.testing.schema import Table, Column
class PolymorphicCircularTest(fixtures.MappedTest):
run_setup_mappers = 'once'
@classmethod
def define_tables(cls, metadata):
global Table1, Table1B, Table2, Table3, Data
table1 = Table('table1', metadata,
Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
Column('related_id', Integer, ForeignKey('table1.id'), nullable=True),
Column('type', String(30)),
Column('name', String(30))
)
table2 = Table('table2', metadata,
Column('id', Integer, ForeignKey('table1.id'), primary_key=True),
)
table3 = Table('table3', metadata,
Column('id', Integer, ForeignKey('table1.id'), primary_key=True),
)
data = Table('data', metadata,
Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
Column('node_id', Integer, ForeignKey('table1.id')),
Column('data', String(30))
)
#join = polymorphic_union(
# {
# 'table3' : table1.join(table3),
# 'table2' : table1.join(table2),
# 'table1' : table1.select(table1.c.type.in_(['table1', 'table1b'])),
# }, None, 'pjoin')
join = table1.outerjoin(table2).outerjoin(table3).alias('pjoin')
#join = None
class Table1(object):
def __init__(self, name, data=None):
self.name = name
if data is not None:
self.data = data
def __repr__(self):
return "%s(%s, %s, %s)" % (self.__class__.__name__, self.id, repr(str(self.name)), repr(self.data))
class Table1B(Table1):
pass
class Table2(Table1):
pass
class Table3(Table1):
pass
class Data(object):
def __init__(self, data):
self.data = data
def __repr__(self):
return "%s(%s, %s)" % (self.__class__.__name__, self.id, repr(str(self.data)))
try:
# this is how the mapping used to work. ensure that this raises an error now
table1_mapper = mapper(Table1, table1,
select_table=join,
polymorphic_on=table1.c.type,
polymorphic_identity='table1',
properties={
'nxt': relationship(Table1,
backref=backref('prev', foreignkey=join.c.id, uselist=False),
uselist=False, primaryjoin=join.c.id==join.c.related_id),
'data':relationship(mapper(Data, data))
},
order_by=table1.c.id)
configure_mappers()
assert False
except:
assert True
clear_mappers()
# currently, the "eager" relationships degrade to lazy relationships
# due to the polymorphic load.
# the "nxt" relationship used to have a "lazy='joined'" on it, but the EagerLoader raises the "self-referential"
# exception now. since eager loading would never work for that relationship anyway, its better that the user
# gets an exception instead of it silently not eager loading.
# NOTE: using "nxt" instead of "next" to avoid 2to3 turning it into __next__() for some reason.
table1_mapper = mapper(Table1, table1,
#select_table=join,
polymorphic_on=table1.c.type,
polymorphic_identity='table1',
properties={
'nxt': relationship(Table1,
backref=backref('prev', remote_side=table1.c.id, uselist=False),
uselist=False, primaryjoin=table1.c.id==table1.c.related_id),
'data':relationship(mapper(Data, data), lazy='joined', order_by=data.c.id)
},
order_by=table1.c.id
)
table1b_mapper = mapper(Table1B, inherits=table1_mapper, polymorphic_identity='table1b')
table2_mapper = mapper(Table2, table2,
inherits=table1_mapper,
polymorphic_identity='table2')
table3_mapper = mapper(Table3, table3, inherits=table1_mapper, polymorphic_identity='table3')
configure_mappers()
assert table1_mapper.primary_key == (table1.c.id,), table1_mapper.primary_key
def test_one(self):
self._testlist([Table1, Table2, Table1, Table2])
def test_two(self):
self._testlist([Table3])
def test_three(self):
self._testlist([Table2, Table1, Table1B, Table3, Table3, Table1B, Table1B, Table2, Table1])
def test_four(self):
self._testlist([
Table2('t2', [Data('data1'), Data('data2')]),
Table1('t1', []),
Table3('t3', [Data('data3')]),
Table1B('t1b', [Data('data4'), Data('data5')])
])
def _testlist(self, classes):
sess = create_session( )
# create objects in a linked list
count = 1
obj = None
for c in classes:
if isinstance(c, type):
newobj = c('item %d' % count)
count += 1
else:
newobj = c
if obj is not None:
obj.nxt = newobj
else:
t = newobj
obj = newobj
# save to DB
sess.add(t)
sess.flush()
# string version of the saved list
assertlist = []
node = t
while (node):
assertlist.append(node)
n = node.nxt
if n is not None:
assert n.prev is node
node = n
original = repr(assertlist)
# clear and query forwards
sess.expunge_all()
node = sess.query(Table1).filter(Table1.id==t.id).first()
assertlist = []
while (node):
assertlist.append(node)
n = node.nxt
if n is not None:
assert n.prev is node
node = n
forwards = repr(assertlist)
# clear and query backwards
sess.expunge_all()
node = sess.query(Table1).filter(Table1.id==obj.id).first()
assertlist = []
while (node):
assertlist.insert(0, node)
n = node.prev
if n is not None:
assert n.nxt is node
node = n
backwards = repr(assertlist)
# everything should match !
assert original == forwards == backwards
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