request parsing with ujson

[Midnighter]

Since you are advertising the use of ujson, I was expecting that it is being used as a drop-in everywhere in starlette. When I post to a simple route handler without any body content, I see an exception coming from the standard library, however. Is this a special case when there is no body content or is ujson only used in serializing the JSONResponse?

Code:

@app.route('/', methods=["POST"], )
async def search(request: Request) -> JSONResponse:
    query = await request.json()
    return query

Traceback:

web_1  |     query = await request.json()
web_1  |   File "/usr/local/lib/python3.7/site-packages/starlette/requests.py", line 96, in json
web_1  |     self._json = json.loads(body)
web_1  |   File "/usr/local/lib/python3.7/json/__init__.py", line 348, in loads
web_1  |     return _default_decoder.decode(s)
web_1  |   File "/usr/local/lib/python3.7/json/decoder.py", line 337, in decode
web_1  |     obj, end = self.raw_decode(s, idx=_w(s, 0).end())
web_1  |   File "/usr/local/lib/python3.7/json/decoder.py", line 355, in raw_decode
web_1  |     raise JSONDecodeError("Expecting value", s, err.value) from None
web_1  | json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

[alexbotello]

...is ujson only used in serializing the JSONResponse?

This is the answer right here.

[tomchristie]

Closing this off. In fact I think we should possibly add a UJSONResponse, and only use ujson when that's done so explicitly. (Since it has some edge-cases where its behavior differs.)

[gsakkis]

and only use ujson when that's done so explicitly.

It would be quite handy if there was a way to (explicitly) tell starlette to use ujson everywhere. I only realized this isn't the case by profiling a high volume route that's already using UJSONResponse and seeing json.loads taking more time than the rest of the (non-trivial) route-specific logic combined.