[Python] Make every field as optional with Pydantic

I'm making an API with FastAPI and Pydantic.

I would like to have some PATCH endpoints, where 1 or N fields of a record could be edited at once. Moreover, I would like the client to only pass the necessary fields in the payload.

Example:

class Item(BaseModel):
name: str
description: str
price: float
tax: float


@app.post("/items", response_model=Item)
async def post_item(item: Item):
...

@app.patch("/items/{item_id}", response_model=Item)
async def update_item(item_id: str, item: Item):
...


In this example, for the POST request, I want every field to be required. However, in the PATCH endpoint, I don't mind if the payload only contains, for example, the description field. That's why I wish to have all fields as optional.

Naive approach:

class UpdateItem(BaseModel):
name: Optional[str] = None
description: Optional[str] = None
price: Optional[float] = None
tax: Optional[float]


But that would be terrible in terms of code repetition.

Any better option?

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