fastapi: Issue: Fatal Python error: Cannot recover from stack overflow.

This was caused by the new release (0.61.0) (jsonable_encoder).

The problem is the line that contains: obj_data = jsonable_encoder(db_obj)

Possible solution:

# Your function
  def update(self, db: Session, *, db_obj: ModelType, obj_in: Union[UpdateSchemaType, Dict[str, Any]]) -> ModelType:
    obj_data = db_obj.as_dict() # HERE!
    if isinstance(obj_in, dict):
      update_data = obj_in
    else:
      update_data = obj_in.dict(exclude_unset=True)
    for field in obj_data:
      if field in update_data:
        setattr(db_obj, field, update_data[field])
    db.add(db_obj)
    db.commit()
    db.refresh(db_obj)
    return db_obj

# SQLAlchemy Base object
@as_declarative()
class Base:
    def as_dict(self) -> dict:
        return {c.key: getattr(self, c.key) for c in inspect(self).mapper.column_attrs}

But I don’t know why we have this error message, I need to check.

EDIT: As reminded by @imadmoussa1:

from sqlalchemy import inspect

Does it mean jsonable_encoder is broken? It is unclear why the issue was closed.

This fix does not help in my case, after applying the above fix, I still get the error message:

Fatal Python error: Cannot recover from stack overflow.

Thread 0x00007fa28e7bc700 (most recent call first):
  File "/usr/local/lib/python3.7/concurrent/futures/thread.py", line 78 in _worker
  File "/usr/local/lib/python3.7/threading.py", line 870 in run
  File "/usr/local/lib/python3.7/threading.py", line 926 in _bootstrap_inner
  File "/usr/local/lib/python3.7/threading.py", line 890 in _bootstrap

Thread 0x00007fa28effd700 (most recent call first):
  File "/usr/local/lib/python3.7/concurrent/futures/thread.py", line 78 in _worker
  File "/usr/local/lib/python3.7/threading.py", line 870 in run
  File "/usr/local/lib/python3.7/threading.py", line 926 in _bootstrap_inner
  File "/usr/local/lib/python3.7/threading.py", line 890 in _bootstrap

Current thread 0x00007fa28f7fe700 (most recent call first):
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/type_api.py", line 67 in operate
  File "<string>", line 1 in <lambda>
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/operators.py", line 432 in __getitem__
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/elements.py", line 762 in operate

Update, fixed my issue:

    check_item = crud.item.get_by_user(
        db=db, id=item_id, user_id=current_user.id
    )
    pd_check_item = ItemCheck.from_orm(check_item) # Fix: convert from DB model to pydantic model 
    check_data = jsonable_encoder(pd_check_item, exclude_none=True) # Breaks if accept db model directly
    return check_data

It seems jsonable_encoder can no longer accept a DB model and convert the data, it only accepts a pydantic model.

Hi @sv8083 you should import the inspect from sqlalchemy

from sqlalchemy import inspect

Thanks for the discussion here everyone! I’m sorry for the inconveniences 🤦 . This was fixed in 0.61.1. The current latest is 0.62.0.

For me, and also using sqlalchemy, I was simply forgetting to add response_model=schemaName to my endpoint:

Before:

@app.get("/users/me")
async def read_users_me(current_user: schemas.User = Depends(get_current_active_user)):
    return current_user

After:

@app.get("/users/me", response_model=schemas.User)
async def read_users_me(current_user: schemas.User = Depends(get_current_active_user)):
    return current_user

How to import ItemCheck

I’m using the project generator, so you can define your own pydantic models like ItemCheck, you can refer to the samples in project generator here: https://github.com/tiangolo/full-stack-fastapi-postgresql/blob/master/{{cookiecutter.project_slug}}/backend/app/app/schemas/item.py#L33 As long as it is based on ItemInDBBase, it will support orm_mode

Another approach I was trying locally was to use load a pydantic model from the orm model, get the dict(), then iterate that, such as:

obj_data = UserInDB.from_orm(db_obj).dict()

…now I know that doesnt perfectly fit into CRUDBase unless we refactor it to also hold onto a DBSchemaType in addition to CreateSchemaType and UpdateSchemaType

You’re welcome! @imadmoussa1 Do you mind closing the issue then? 😎 🎉

@Kludex Thank you, Your solution fixed my problem.