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primaryjoin with bindparam test case
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from sqlalchemy import Column, Integer, ForeignKey, bindparam, and_, create_engine | |
from sqlalchemy.orm import relationship, sessionmaker | |
from sqlalchemy.ext.declarative import declarative_base | |
Base = declarative_base() | |
def get_age(): | |
"""Method that would get some data from a Flask request context, although | |
the behaviour is the same regardless.""" | |
return 15 | |
class Child(Base): | |
__tablename__ = 'child' | |
id = Column('id', Integer, primary_key=True) | |
age = Column(Integer) | |
parent_id = Column(Integer, ForeignKey('parent.id')) | |
class Parent(Base): | |
__tablename__ = 'parent' | |
id = Column('id', Integer, primary_key=True) | |
@classmethod | |
def __declare_last__(cls): | |
cls.children_by_age = relationship( | |
Child, | |
lazy='joined', | |
primaryjoin=and_( | |
Parent.id == Child.parent_id, | |
Child.age == bindparam('age', callable_=get_age) | |
) | |
) | |
### DB setup ### | |
engine = create_engine('sqlite://') | |
session = sessionmaker(bind=engine)() | |
Base.metadata.create_all(engine) | |
parent = Parent() | |
session.add(parent) | |
session.commit() | |
c1, c2, c3 = [ | |
Child(age=10, parent_id=parent.id), | |
Child(age=15, parent_id=parent.id), | |
Child(age=20, parent_id=parent.id) | |
] | |
session.add_all([c1, c2, c3]) | |
session.commit() | |
### Test case that shows odd behaviour ### | |
assert len(parent.children_by_age) == 0 # not there, unsurprisingly | |
session.expunge_all() | |
parent = session.query(Parent).one() | |
assert len(parent.children_by_age) == 1 # the Child object is now loaded | |
session.add(parent) | |
session.commit() | |
assert len(parent.children_by_age) == 0 # the Child object is gone! | |
session.refresh(parent) | |
assert len(parent.children_by_age) == 1 # it's back again |
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from flask import Flask, has_request_context | |
from sqlalchemy import Column, Integer, ForeignKey, bindparam, and_, create_engine | |
from sqlalchemy.orm import relationship, sessionmaker | |
from sqlalchemy.ext.declarative import declarative_base | |
Base = declarative_base() | |
def get_age(): | |
"""Method that would get some data from a Flask request context, although | |
the behaviour is the same regardless.""" | |
if has_request_context(): | |
return 15 | |
class Child(Base): | |
__tablename__ = 'child' | |
id = Column('id', Integer, primary_key=True) | |
age = Column(Integer) | |
parent_id = Column(Integer, ForeignKey('parent.id')) | |
class Parent(Base): | |
__tablename__ = 'parent' | |
id = Column('id', Integer, primary_key=True) | |
@classmethod | |
def __declare_last__(cls): | |
cls.children_by_age = relationship( | |
Child, | |
lazy='joined', | |
primaryjoin=and_( | |
Parent.id == Child.parent_id, | |
Child.age == bindparam('age', callable_=get_age) | |
) | |
) | |
### DB setup ### | |
app = Flask(__name__) | |
engine = create_engine('sqlite://') | |
session = sessionmaker(bind=engine)() | |
Base.metadata.create_all(engine) | |
parent = Parent() | |
session.add(parent) | |
session.commit() | |
c1, c2, c3 = [ | |
Child(age=10, parent_id=parent.id), | |
Child(age=15, parent_id=parent.id), | |
Child(age=20, parent_id=parent.id) | |
] | |
session.add_all([c1, c2, c3]) | |
session.commit() | |
### Test case that shows odd behaviour ### | |
assert len(parent.children_by_age) == 0 # not there, unsurprisingly | |
session.expunge_all() | |
parent = session.query(Parent).one() | |
assert len(parent.children_by_age) == 0 # the Child object is not there, no request context | |
with app.test_request_context(): | |
parent = session.query(Parent).one() | |
assert len(parent.children_by_age) == 0 # still not there, needs refresh | |
session.refresh(parent) # expire + new query will have the same result | |
assert len(parent.children_by_age) == 1 # now it works | |
session.add(parent) | |
session.commit() | |
assert len(parent.children_by_age) == 0 # gone after commit | |
session.refresh(parent) | |
assert len(parent.children_by_age) == 1 # back again |
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