I have an endpoint which returns a Pydantic object. However, I would like a response code other than 200 in some cases (for example if my service in not healthy). How can I achieve that with FastAPI?
class ServiceHealth(BaseModel):
http_ok: bool = True
database_ok: bool = False
def is_everything_ok(self) -> bool:
return self.http_ok and self.database_ok
@router.get("/health")
def health() -> ServiceHealth:
return ServiceHealth()
You can return a Response Directly.
For example, you can use JSONResponse and set the status manually:
@router.get("/health")
async def health() -> ServiceHealth:
response = ServiceHealth()
if response.is_everything_ok():
return JSONResponse(content=response.dict(), status_code=200)
return JSONResponse(content=response.dict(), status_code=500)
Also, there is a handy status.py which you can import from fastapi that contains all the available status codes:
from fastapi import status
@router.get("/health")
async def health() -> ServiceHealth:
response = ServiceHealth()
if response.is_everything_ok():
return JSONResponse(content=response.dict(), status_code=status.HTTP_200_OK)
return JSONResponse(content=response.dict(), status_code=status.HTTP_500_INTERNAL_SERVER_ERROR)
JSONResponse(content=some_dict, ....), please make sure that all objects in the dictionary that is being returned are JSON-serializable objects, otherwise a TypeError: Object of type ... is not JSON serializable would be raised. In that case, one should either convert such objects to a type that is JSON-serializable (e.g., str) on their own, or use FastAPI's jsonable_encoder() function that would automatically do this (see this answer for more details and examples).
datetimes for example, that are not JSON serializable) in order to make sure they will be serialized correctly is to use the following combo: json.load(pydantic_instance.json())JSONResponse will use json.dumps() behind the scenes (as explained in the links provided above).return Response(model.json(), media_type='application/json', status=status.HTTP_200_OK). See the linked answers above for more details.
status is now status_code for 0.104.1Just specify the status_code keyword-argument, when initializing your APIRoute. It is passed along by all route decorators as far as I know, including APIRouter.get.
from fastapi import FastAPI
from pydantic import BaseModel
class ServiceHealth(BaseModel):
http_ok: bool = True
database_ok: bool = False
api = FastAPI()
@api.get("/health", status_code=299)
def health() -> ServiceHealth:
return ServiceHealth()
Performing a GET on that route still returns the expected JSON {"http_ok":true,"database_ok":false} with the HTTP status code 299 (just to demonstrate, not a "real" status code).
There are a few restrictions that FastAPI places on that argument. Notably, you cannot return a body, if you define a 304 status code or any informational (1xx) status code.
