fastapi 0.80.0

on Python PyPI

Breaking Changes - Fixes

• 🐛 Fix response_model not invalidating None. PR #2725 by @hukkin.

If you are using response_model with some type that doesn't include None but the function is returning None, it will now raise an internal server error, because you are returning invalid data that violates the contract in response_model. Before this release it would allow breaking that contract returning None.

For example, if you have an app like this:

from fastapi import FastAPI
from pydantic import BaseModel

class Item(BaseModel):
    name: str
    price: Optional[float] = None
    owner_ids: Optional[List[int]] = None

app = FastAPI()

@app.get("/items/invalidnone", response_model=Item)
def get_invalid_none():
    return None

...calling the path /items/invalidnone will raise an error, because None is not a valid type for the response_model declared with Item.

You could also be implicitly returning None without realizing, for example:

from fastapi import FastAPI
from pydantic import BaseModel

class Item(BaseModel):
    name: str
    price: Optional[float] = None
    owner_ids: Optional[List[int]] = None

app = FastAPI()

@app.get("/items/invalidnone", response_model=Item)
def get_invalid_none():
    if flag:
        return {"name": "foo"}
    # if flag is False, at this point the function will implicitly return None

If you have path operations using response_model that need to be allowed to return None, make it explicit in response_model using Union[Something, None]:

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

class Item(BaseModel):
    name: str
    price: Optional[float] = None
    owner_ids: Optional[List[int]] = None

app = FastAPI()

@app.get("/items/invalidnone", response_model=Union[Item, None])
def get_invalid_none():
    return None

This way the data will be correctly validated, you won't have an internal server error, and the documentation will also reflect that this path operation could return None (or null in JSON).

Fixes

• ⬆ Upgrade Swagger UI copy of oauth2-redirect.html to include fixes for flavors of authorization code flows in Swagger UI. PR #3439 initial PR by @koonpeng.
• ♻ Strip empty whitespace from description extracted from docstrings. PR #2821 by @and-semakin.
• 🐛 Fix cached dependencies when using a dependency in Security() and other places (e.g. Depends()) with different OAuth2 scopes. PR #2945 by @laggardkernel.
• 🎨 Update type annotations for response_model, allow things like Union[str, None]. PR #5294 by @tiangolo.

Translations

• 🌐 Fix typos in German translation for docs/de/docs/features.md. PR #4533 by @0xflotus.
• 🌐 Add missing navigator for encoder.md in Korean translation. PR #5238 by @joonas-yoon.
• (Empty PR merge by accident) #4913.