Hi Mike
Thanks for looking at my code. Next time I'll post an testcase like you.
Sorry for that one. And I cannot believe it. But it works now.
I also updated SQLAlchemy, flast-RESTful, flask-migrate and so on, to
their newest version.
And now it seems to work. And problem before was
> assert m2.daughter:id is None
This failed. But I tried and tried and tried in out production code
isntead of sampling a small testcase like you. bad idea.
And I really have NO idea why it works now. But I think I stop here for
today and can have fun at wekkeend.. instead of thinking thinking
thinking about that!!
Many thanks!
Mike Bayer <mike...@zzzcomputing.com> schrieb am Fr. 18. Dez. 2020 um
16:31:
hey there -
these mappings are pretty good, as is always the case I cannot predict
why an issue is occurring, or usually even understand the issue,
without running the code. your code is pretty runnable with a few
imports added so that's great. however adding an assertion for the
condition you describe "m2.daughter is not None" is not reproducible
on my end. Try out the script below and see if you have different
results.
from sqlalchemy import Column
from sqlalchemy import create_engine
from sqlalchemy import ForeignKey
from sqlalchemy import Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship
from sqlalchemy.orm import Session
Base = declarative_base()
class Super(Base):
__tablename__ = "super"
id = Column(Integer, primary_key=True)
class Mama(Super):
__tablename__ = "mama"
id = Column(Integer, ForeignKey("super.id"), primary_key=True)
daughter_id = Column(Integer, ForeignKey("daughter.id"))
daughter = relationship(
"Daughter", foreign_keys=[daughter_id], back_populates="mama"
)
class Daughter(Super):
__tablename__ = "daughter"
id = Column(Integer, ForeignKey("super.id"), primary_key=True)
mama = relationship(
"Mama",
foreign_keys=[Mama.daughter_id],
uselist=False,
back_populates="daughter",
)
e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)
session = Session(e)
m1 = Mama()
m2 = Mama()
d1 = Daughter()
d2 = Daughter()
session.add(m1)
session.add(m2)
session.add(d1)
session.add(d2)
session.commit()
m1.daughter = d1
m2.daughter = d2
session.commit()
m1.daughter = d2
session.commit()
assert m2.daughter is None
On Fri, Dec 18, 2020, at 2:01 AM, 'Sören Textor' via sqlalchemy wrote:
Hello
I have a huge problem with süecific "one to one" relation.
Woking (it's the tutorial code)
class Son(db.Model):
__tablename__ = 'son'
id = db.Column(db.Integer, primary_key=True)
papa_id = db.Column(db.Integer, db.ForeignKey('papa.id'))
papa = db.relationship("Papa", foreign_keys=[papa_id],
back_populates="son")
class Papa(db.Model):
__tablename__ = 'papa'
id = db.Column(db.Integer, primary_key=True)
son = db.relationship("Son", uselist=False,
back_populates="papa")
main:
p1 = Papa()
p2 = Papa()
s1 = Son()
s2 = Son()
db.session.add(p1)
db.session.add(p2)
db.session.add(s1)
db.session.add(s2)
db.session.commit()
p1.son = s1
p2.son = s2
db.session.commit()
p1.son = s2
db.session.commit()
Works like a charm. afterwards every relation is correct
My code (I have to use a super class, that's the only difference):
class Super(db.Model):
__tablename__ = 'super'
id = db.Column(db.Integer, primary_key=True)
class Mama(Super):
__tablename__ = 'mama'
id = db.Column(db.Integer, db.ForeignKey('super.id'),
primary_key=True)
daughter_id = db.Column(db.Integer, db.ForeignKey('daughter.id'))
daughter = db.relationship("Daughter",
foreign_keys=[daughter_id], back_populates="mama")
class Daughter(Super):
__tablename__ = 'daughter'
id = db.Column(db.Integer, db.ForeignKey('super.id'),
primary_key=True)
mama = db.relationship("Mama", foreign_keys=[Mama.daughter_id],
uselist=False, back_populates="daughter")
main:
m1 = Mama()
m2 = Mama()
d1 = Daughter()
d2 = Daughter()
db.session.add(m1)
db.session.add(m2)
db.session.add(d1)
db.session.add(d2)
db.session.commit()
m1.daughter = d1
m2.daughter = d2
db.session.commit()
m1.daughter = d2
db.session.commit()
everything is correct EXCEPT:
m2.daughter! it still points on d2 instead of None. And the table
contains still the daughter_id of d2.
Thus, what foreign key did I miss?
All the best and stay healthy!
SirAnn
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