when working with FastAPI will 'strip off' some of the fields in schema

[JackySu]

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Example Code

models.py

class Category(SQLModel, table=True):
    __tablename__ = 'categories'
    categoryId: int = Field(primary_key=True, nullable=False)
    categoryName: str

    tags: List["Tag"] = Relationship(back_populates="category")


class Tag(SQLModel, table=True):
    __tablename__ = 'tags'
    tagId: int = Field(primary_key=True, nullable=False)
    tagName: str
    tagNameShort: str
    categoryId: int = Field(default=None, foreign_key="categories.categoryId")

    category: Category = Relationship(back_populates="tags")

api.py

@router.get("/tags")
async def get_category_with_tags(session: AsyncSession = Depends(get_session)):

    r = await session.execute(select(Category).options(selectinload(Category.tags)).order_by(Category.categoryId))
    return r.scalars().all()

Description

the r.scalars().all() goes well with an instance of class Category which contains a list of tags belonging to it, but after return there is no tags field in the response of FastAPI
the response body looks like this

[
    {
        "categoryId": 1,
        "categoryName": "test"
    }
]

with no tags included

Operating System

Windows

Operating System Details

No response

SQLModel Version

0.0.8

Python Version

3.11.1

Additional Context

No response

[JackySu]

this issue can be solved by these modifications
models.py

class CategoryBase(SQLModel):
    categoryId: int = Field(primary_key=True, nullable=False)
    categoryName: str


class Category(CategoryBase, table=True):
    __tablename__ = 'categories'
    tags: List["Tag"] = Relationship(back_populates="category")


class CategoryWithTags(CategoryBase):
    tags: List["Tag"] = []

CategoryWithTags.update_forward_refs()

api.py

@router.get("/tags", response_model=List[CategoryWithTags])
async def get_category_with_tags(session: AsyncSession = Depends(get_session)) -> List[CategoryWithTags]:

    r = await session.execute(select(Category).options(selectinload(Category.tags)).order_by(Category.categoryId))
    return r.scalars().all()

references to the document https://sqlmodel.tiangolo.com/tutorial/fastapi/relationships/