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from sqlalchemy import ForeignKey
from sqlalchemy import Integer
from sqlalchemy import String
from sqlalchemy.orm import backref
from sqlalchemy.orm import configure_mappers
from sqlalchemy.orm import relationship
from sqlalchemy.testing import fixtures
from sqlalchemy.testing.fixtures import fixture_session
from sqlalchemy.testing.schema import Column
from sqlalchemy.testing.schema import Table
class PolymorphicCircularTest(fixtures.MappedTest):
run_setup_mappers = "once"
@classmethod
def define_tables(cls, metadata):
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)),
)
Table(
"table2",
metadata,
Column("id", Integer, ForeignKey("table1.id"), primary_key=True),
)
Table(
"table3",
metadata,
Column("id", Integer, ForeignKey("table1.id"), primary_key=True),
)
Table(
"data",
metadata,
Column(
"id", Integer, primary_key=True, test_needs_autoincrement=True
),
Column("node_id", Integer, ForeignKey("table1.id")),
Column("data", String(30)),
)
@classmethod
def setup_mappers(cls):
table1, table2, table3, data = cls.tables(
"table1", "table2", "table3", "data"
)
Base = cls.Basic
class Table1(Base):
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(Base):
def __init__(self, data):
self.data = data
def __repr__(self):
return "%s(%s, %s)" % (
self.__class__.__name__,
self.id,
repr(str(self.data)),
)
# 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 = cls.mapper_registry.map_imperatively(
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(
cls.mapper_registry.map_imperatively(Data, data),
lazy="joined",
order_by=data.c.id,
),
},
)
cls.mapper_registry.map_imperatively(
Table1B, inherits=table1_mapper, polymorphic_identity="table1b"
)
cls.mapper_registry.map_imperatively(
Table2,
table2,
inherits=table1_mapper,
polymorphic_identity="table2",
)
cls.mapper_registry.map_imperatively(
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):
Table1, Table2 = self.classes("Table1", "Table2")
self._testlist([Table1, Table2, Table1, Table2])
def test_two(self):
Table3 = self.classes.Table3
self._testlist([Table3])
def test_three(self):
Table1, Table1B, Table2, Table3 = self.classes(
"Table1", "Table1B", "Table2", "Table3"
)
self._testlist(
[
Table2,
Table1,
Table1B,
Table3,
Table3,
Table1B,
Table1B,
Table2,
Table1,
]
)
def test_four(self):
Table1, Table1B, Table2, Table3, Data = self.classes(
"Table1", "Table1B", "Table2", "Table3", "Data"
)
self._testlist(
[
Table2("t2", [Data("data1"), Data("data2")]),
Table1("t1", []),
Table3("t3", [Data("data3")]),
Table1B("t1b", [Data("data4"), Data("data5")]),
]
)
def _testlist(self, classes):
Table1 = self.classes.Table1
sess = fixture_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)
.order_by(Table1.id)
.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)
.order_by(Table1.id)
.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
|
