Relationship attribute not in model schema

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Example Code

from fastapi import FastAPI
from sqlmodel import Field, Relationship, SQLModel, create_engine, Session, select


class Child(SQLModel, table=True):
    __tablename__ = "child"
    id: int = Field(default=None, primary_key=True)
    parent_id: int = Field(default=None, foreign_key="parent.id")
    parent: "Parent" = Relationship(back_populates="children")


class Parent(SQLModel, table=True):
    __tablename__ = "parent"
    id: int = Field(default=None, primary_key=True)
    children: List[Child] = Relationship(
        back_populates="parent",
        sa_relationship_kwargs={"lazy": "joined"},
    )


engine = create_engine("sqlite:///./test.db", connect_args={'check_same_thread': False})
SQLModel.metadata.drop_all(engine)
SQLModel.metadata.create_all(engine)
with Session(engine) as session:
    session.add(Parent(id=0))
    session.add(Child(id=0, parent_id=0))
    session.add(Child(id=1, parent_id=0))
    session.commit()


app = FastAPI()
@app.get("/parent", response_model=Parent)
def get_parent():
    with Session(engine) as session:
        parent = session.exec(select(Parent)).first()
        print(parent)
        # id=0 children=[Child(parent_id=0, id=0), Child(parent_id=0, id=1)]
        return parent


print(Parent.schema())
# {'title': 'Parent', 'type': 'object', 'properties': {'id': {'title': 'Id', 'type': 'integer'}}}
# Repare that there is no children attribute

Description

I have two related models (one parent to many children). And that relationship is eager, as you can see when I select a parent and print it, it is possible to see its children too. But the problem happens when I want to cast the result from the select statement to a parent model, using for example the from_orm function, because there is no attribute named children on the parent schema. My problem is probably related to this issue: #224.

Operating System

Windows

Operating System Details

No response

SQLModel Version

0.0.6

Python Version

3.10.2

Additional Context

No response

[alp09]

@AdamMisiak I had a problem where relationship attributes would not appear at all. Aparently SQLAlchemy 1.4.36 (current version is 1.4.37) breaks relationships (source).

I installed version 1.4.35 and it fixed my issue, hope it fixes yours too!

[tiangolo]

Hey there @carlosporta! You need to declare a model that explicitly includes the children for the response_model, otherwise you could end up with infinite recursion.

As @4linuxfun says, you can read the docs explaining it, the relevant section is here: https://sqlmodel.tiangolo.com/tutorial/fastapi/relationships/#dont-include-all-the-data

---

About the issue mentioned by @alp09, that one is reported here: https://github.com/tiangolo/sqlmodel/issues/315, it was solved here: https://github.com/tiangolo/sqlmodel/pull/322, it will be available in the next version, in a couple of hours, SQLModel 0.0.7.