How to exclude Optional unset values from a Pydantic model using FastAPI?

You can use exclude_none param of Pydantic’s model.dict(…):

class Text(BaseModel):
    id: str
    text: str = None


class TextsRequest(BaseModel):
    data: list[Text]
    n_processes: Optional[int]


request = TextsRequest(**{"data": [{"id": "1", "text": "The text 1"}]})
print(request.dict(exclude_none=True))

Output:

{'data': [{'id': '1', 'text': 'The text 1'}]}

Also, it’s more idiomatic to write Optional[int] instead of Union[int, None].