Here is my code snippet: from fastapi_pagination import Page, add_pagination from fastapi_pagination.ext.sqlalchemy import paginate @app.get("/clients", response_model=Page[PydanticModel]) def get_items( db: Session = Depends(get_db) ) -> Any: items = paginate( db.query(Model) .filter(...) ) ... # do some extra manipulations .. ... items.items = new_items return items When I specify Page[PydenticModel] in the response_model it generates an issue with paginte() because it's not the final response type. The PydenticModel correspond to new_items and not items (returned from paginate()), pydantic.error_wrappers.ValidationError: validation errors for Page[PydanticModel] Note: I don't want to use Page[Any] in order to keep a good a Swagger docs Continue reading...