werkzeug.exceptions.BadRequest (400) is converted to internal server error (500)

[Vincas Dargis]

If we have:

@jsonrpc.method('MyApp.index')
@jwt_required()
def index(name: str) -> str:
    raise werkzeug.exceptions.BadRequest("bad parameter")

In result we get (from console output of Flask server):

<..backtrace..>
werkzeug.exceptions.BadRequest: 400 Bad Request: bad parameter
127.0.0.1 - - [06/Sep/2022 15:48:52] "POST /myapi HTTP/1.1" 500 -

requests.post() and then .raise_for_status() results in:

requests.exceptions.HTTPError: 500 Server Error: INTERNAL SERVER ERROR for url: http://127.0.0.1:5000/myapi

It would be nice to be able to validate parameters ourselves, and respond with appropriate error codes and messages to the API user.

[Nycholas Oliveira]

Hi @Talkless,

Yes, according to JSON-RPC specification, every code errors are here[1], and there is a range of custom errors:

-32000 to -32099 | Server error | Reserved for implementation-defined server-errors.

You can use the JSONRPCError[2] to do it, for example:

error = JSONRPCError(message="I'm a teapot", code=-32768, data={'data': [1, 2, 3]}, status_code=418)
assert error.code == -32768
assert error.message == "I'm a teapot"
assert error.data == {'data': [1, 2, 3]}
assert error.status_code == 418
assert error.jsonrpc_format == {
        'code': -32768,
        'data': {'data': [1, 2, 3]},
        'message': "I'm a teapot",
        'name': 'JSONRPCError',
}

[1] - https://www.jsonrpc.org/specification#error_object
[2] - https://github.com/cenobites/flask-jsonrpc/blob/master/src/flask_jsonrpc/exceptions.py#L41