Hi all,
I'm sorry, as I feel like this is kind of a beginner question. I'd expect
that when I set a column attribute the respective relationship field would
change or at least be marked as changed (so a posterior access can be
loaded later on another access), but I've found a case where it doesn't.
I've tried to find a bit of code to represent what I'm struggling with,
hopefully it will be clear enough.
# --- START ---
from sqlalchemy import Column, create_engine, ForeignKey, Integer, String
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy.ext.declarative import declarative_base
engine = create_engine("sqlite://", echo=True)
Session = sessionmaker(engine)
Base = declarative_base()
class Company(Base):
__tablename__ = "company"
company_id = Column(Integer, primary_key=True)
name = Column(String(50))
class Project(Base):
__tablename__ = "project"
project_id = Column(Integer, primary_key=True)
name = Column(String(50))
company_id = Column(Integer, ForeignKey("company.company_id"),
index=True)
company = relationship("Company")
Base.metadata.create_all(engine)
session = Session()
c = Company(name="First Company")
p = Project(name="First Project")
session.add(c)
session.add(p)
assert p.company is None
assert p.company_id is None
# Case 1: update the _id doesn't seem to reflect
p.company_id = c.company_id
assert p.company is None
assert p.company_id == c.company_id
session.flush()
# Wasn't expecting the None here
assert p.company is None
assert p.company_id is None
session.refresh(p)
# Wasn't expecting the None here
assert p.company is None
assert p.company_id is None
# Case 2: update the relation works as expected
p.company = c
assert p.company == c
assert p.company_id is None
session.flush()
assert p.company == c
assert p.company_id == c.company_id
session.refresh(p)
assert p.company == c
assert p.company_id == c.company_id
# --- END ---
Sorry for bothering, but I'm really puzzled/stuck and feel like I've missed
something important,
João
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