Automatically omit "params" when it's empty

[Makman2]

Hello 😄

I would propose to remove the "params" field in Request.serialize not only when it's None, but also when it's empty (i.e. when calling a method without any parameters).

Motivations:

• Performance in the form of smaller messages

• For my particular use-case I have a server that does not support empty objects/dicts specifically (we have a C++ implementation without any argument-name mapping - only positional arguments work). I am currently doing a workaround by monkey-patching the implementation of serialize with:

  original_serialize = Request.serialize
  def remove_empty_params(request: Request):
      data = json.loads(original_serialize(request))
      if 'params' in data and len(data['params']) == 0:
          del data['params']
      return json.dumps(data)
  Request.serialize = remove_empty_params

I hope that would be a worthwile addition. I would gladly submit a PR if this is deemed useful 😄

EDIT:

Forgot to mention the actual reference that omitting "params" is actually possible according to the JSON-RPC spec.

[emlove]

Thanks for the proposal, yeah that makes sense to me! If you're willing to put together a PR I'd be happy to merge. Please make sure to include tests!

[Makman2]

@emlove submitted 😉