i want to redefine the "Validation Error"

[tonglin96]

i want to change the status code and response body for "validation error",what should i do ?

[dmontagu]

I haven't confirmed this works, but you should be able to do:

async def custom_request_validation_exception_handler(
    request: Request, exc: RequestValidationError
) -> JSONResponse:
    # change this as you like, including possibly the return type
    return JSONResponse(
        status_code=HTTP_422_UNPROCESSABLE_ENTITY, content={"detail": exc.errors()}
    )

...

app = FastAPI(...)

...

app.add_exception_handler(
    fastapi.exceptions.RequestValidationException,
    custom_request_validation_exception_handler
)

[tonglin96]

app.add_exception_handler(
    fastapi.exceptions.RequestValidationException,
    custom_request_validation_exception_handler
)

but i want this exception shows in doc,it looks like must change the source code

[tonglin96]

it looks like i cant cover the "RequestValidationError", so i create a new exception like this:
`class ValidException(Exception):
def init(self, code, msg):
self.code = code
self.msg = msg

async def custom_request_validation_exception_handler(
request: Request, exc: ValidException
) -> JSONResponse:
# change this as you like, including possibly the return type
return JSONResponse(
status_code=200, content={"code": exc.code, "msg": exc.msg}
)

app.add_exception_handler(
ValidException,
custom_request_validation_exception_handler
)
`

and i manually raise this exception

[tiangolo]

Yep, as @dmontagu says. It's documented here: https://fastapi.tiangolo.com/tutorial/handling-errors/#override-request-validation-exceptions

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