`RequestRouter` doesn't recognise parameters annotated with the `CompositeMetadata` type when named other than `composite_metadata`

[km-64]

According to the tutorial docs for rsocket-py, an argument type named composite_metadata or an argument (with any name) annotated with the CompositeMetadata type should be passed an instance of CompositeMetadata, however the actual behaviour of the router is to pass a Payload instance in the case of the latter. The only effective way to acquire the metadata is to name the argument composite_metadata. The annotation is effectively ignored by the router.

All methods decorated by the request router accept two optional arguments:

Any argument named composite_metadata (regardless of type-hint), or type-hinted with CompositeMetadata will receive a CompositeMetadata instance containing parsed composite metadata
Any other argument without a type-hint, or type-hinted with Payload will receive the request's payload
https://rsocket.io/guides/rsocket-py/tutorial/request_routing#routing-request-handler

Behaviour

Name and type (works)

router = RequestRouter()
@router.response("example") 
async def example_response(payload: Payload, composite_metadata: CompositeMetadata) -> Awaitable[Payload]:
    assert isinstance(composite_metadata, CompositeMetadata)  # passes
    return create_response(ensure_bytes("test"))

Name without type (works)

router = RequestRouter()
@router.response("example") 
async def example_response(payload: Payload, composite_metadata) -> Awaitable[Payload]:
    assert isinstance(composite_metadata, CompositeMetadata)  # passes
    return create_response(ensure_bytes("test"))

Arbitrary name with type (should work but doesn't)

router = RequestRouter()
@router.response("example") 
async def example_response(payload: Payload, arbitrary_name: CompositeMetadata) -> Awaitable[Payload]:
    assert isinstance(arbitrary_metadata, CompositeMetadata)  # fails
    print(type(arbitrary_metadata))  # parameter_type.annotation is CompositeMetadata
    return create_response(ensure_bytes("test"))

Cause and solution

This is due to the implementation of _collect_route_arguments:

rsocket-py/rsocket/routing/request_router.py

Lines 167 to 187 in a791837

	def _collect_route_arguments(self,
	route_info: RouteInfo,
	payload: Payload,
	composite_metadata: CompositeMetadata):
	route_signature = route_info.signature
	route_kwargs = {}
	for parameter in route_signature.parameters:
	parameter_type = route_signature.parameters[parameter]
	if 'composite_metadata' == parameter or parameter_type.annotation is CompositeMetadata:
	route_kwargs[parameter] = composite_metadata
	else:
	payload_data = payload
	if parameter_type.annotation not in (Payload, parameter_type.empty):
	payload_data = self._payload_deserializer(parameter_type.annotation, payload)
	route_kwargs[parameter] = payload_data
	return route_kwargs

On line 177, the check should access the annotation property of the inspect.Paramter class, but it doesn't do that. So the right hand side of the or operator. Since it checks that the Parameter instance is CompositeMetadata, it will always evaluate to false.

[km-64]

Fixed in e43f97c

[jell-o-fishi]

Yes. i peek at your fork :)