How to remove field value using PATCH

[ameyapathare]

Hi! I am trying to write a PATCH API endpoint that can take a subset of fields and update a product object. Say I have the following schema and endpoint:

class ProductUpdate(Schema):
    name: str = None
    description: str = None
    category_id: uuid.UUID = None

@api.patch("/{product_id}")
def update_product(request, product_id, payload: ProductUpdate):
    product = get_object_or_404(Product, id=product_id)
    print(payload.dict())
    for attr, value in payload.dict().items():
        if value:
            setattr(product, attr, value)
    product.save()
    return {"success": True}

If I just want to update the description, I can send this request body: {"description": "new description"}. It looks like payload.dict() always includes "name": None and "category_id": None.

However, if I want to remove the category_id, with a request body like {"description": "new description", "category_id": None}, I don't know how to know that the "category_id": None was passed in the request body versus was defaulted by django-ninja. Is there any way to allow a PATCH request to remove values from models?

[vitalik]

@ameyapathare

dict method is from pydantic

so you can try with exclude_none

for attr, value in payload.dict(exclude_none=True).items():
   ...

[sebastian-philipp]

https://fastapi.tiangolo.com/tutorial/body-updates/#partial-updates-with-patch might also be helpful

[ameyapathare]

Thanks both! Knowing the dict method was from pydantic was the key unlock here. The parameter I needed was "exclude_unset" (FastAPI documentation contained that as well). Thanks!