How shall i define create sub-optional models in Optional[] working with typing and pydantic libs for FastAPI python?

Question

Hi i'm a beginer in FastAPi, getting this error as

TypeError: typing.Union[pydantic.main.stats, NoneType] is not a generic class.

How shall i create sub-optional models? these are my imports.

from typing import Optional,List
from pydantic import BaseModel, create_model

Answer 1

You can just use an optional nested model, as described in the doc

from typing import Optional, Set

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Image(BaseModel):
    url: str
    name: str


class Item(BaseModel):
    name: str
    description: Optional[str] = None
    price: float
    tax: Optional[float] = None
    tags: Set[str] = []
    image: Optional[Image] = None


# do your stuff