SQLModel Relationships not present in Pydantic model_dump

[konkyrkos]

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Example Code

class Club(SQLModel, table=True):  
    __tablename__ = "clubs"

    updated_at: datetime = Field(sa_type=DateTime, sa_column_kwargs={"server_default": utcnow()})
    id: Optional[int] = Field(nullable=True, index=True, unique=True)
    uid: str = Field(nullable=False, sa_type=String, primary_key=True, sa_column_kwargs={"autoincrement":False})
    name: Optional[str] = Field(default=None, nullable=True)

    members: List[Member] = Relationship(back_populates="club", sa_relationship_kwargs=dict(cascade="all"))

class Member(SQLModel, table=True):  # type: ignore
    __tablename__ = "members"
    id: int = Field(nullable=False, sa_type=Integer, primary_key=True, sa_column_kwargs={
        "autoincrement": False
    })
    club_uid: str = Field(nullable=False, foreign_key="clubs.uid", index=True)

    club: "Club" = Relationship(back_populates="members")

Description

We are trying to update to pydantic v2 (from v1) and latest versions of sqlmodel and sqlalchemy. We have two models connected by a relationship. We want to get a model as a dict along with its relationships (as keys of the dict too). We use club.model_dump(inlcude={'id', 'uid', 'name', 'members'}). In the past instead of .model_dump we used .dict() with the same parameters it worked. Now model_dump method does not work and does not return the relationships as keys of the dict. We have tried various options of the method but nothing did the trick.
Any help and interest in the issue is welcome!
Thank you in advance.

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.21

Python Version

3.10.5

Additional Context

No response

[theblazehen]

@konkyrkos Any chance you may have figured this out?

[monchin]

Would you please offer a minimal reproducible example? An example that uses sqlite and can be directly run, and print the result, and you can tell us what result you expected.

I guess this is because sqlmodel dosen't validate data, so maybe #1041 could work, but I need an example to try.

[madduck]

Here is a minimal example:

from sqlmodel import Field, Relationship, SQLModel


class ParentBase(SQLModel):
    name: str | None


class Parent(ParentBase, table=True):
    id: int | None = Field(default=None, primary_key=True)
    children: list["Child"] = Relationship(back_populates="parent")


class ChildBase(SQLModel):
    name: str
    parentid: int | None = Field(default=None, foreign_key="parent.id")


class Child(ChildBase, table=True):
    id: int | None = Field(default=None, primary_key=True)
    parent: Parent = Relationship(back_populates="children")


class ChildWithParent(ChildBase):
    id: int
    parent: Parent


if __name__ == "__main__":
    p1 = Parent(id=1, name="parent")

    c1 = Child(id=1, parent=p1, name="child1")
    dump = c1.model_dump()
    print(dump)

    c2 = ChildWithParent(id=2, parent=p1, name="child2")
    dump = c2.model_dump()
    print(dump)

The only difference between instances of ChildWithParents and Child models are that in the latter, the parent attribute is default-initialised with a sqlmodel.Relationship. This seems to effect that the Pydantic serialiser doesn't care about the field anymore, and it doesn't include it in the model dump.

I encountered this issue over at FastAPI, and I am glad to be able to further hone down on the problem.

Unless there is a necessary reason for why a field that defaults to a Relationship cannot be part of the Pydantic model, I think it would be great to get that fixed. Because it is one of the core promises of SQLModel that each model is also a Pydantic model, but in this case, I am not sure it is.