Method signature elements that are repeated fields are not handled properly

[software-dov]

Minimal reproducible code:

service MyService {
  rpc MyMethod(MethodRequest) returns (MethodResponse) {
  	option (google.api.method_signature) = "inputs,parameters";
  }
}

message MethodRequest {
  repeated google.protobuf.Value inputs = 1;
}

message MethodResponse {
  google.protobuf.Value output = 1;
}

In the portion of the client method that constructs the request, the following lines occur

 if inputs is not None:
            request.inputs = inputs

This causes protobuf to raise an error because request.intputs is a repeated field.
The solution is to do the following instead:

  if inputs is not None:
          request.inputs.extend(inputs)

[software-dov]

Pretty sure this has been fixed in the templates, but can reopen if it's not actually the case.

[parthea]

This is still an issue in googleapis/python-aiplatform. The owlbot.py file has a workaround. I removed the workaround and the sample tests failed with TypeError. See the build log here. For example :

_________________ test_ucaip_generated_explain_tabular_sample __________________

capsys = <_pytest.capture.CaptureFixture object at 0x7f31d88a1a10>

    def test_ucaip_generated_explain_tabular_sample(capsys):

        explain_tabular_sample.explain_tabular_sample(
>           instance_dict=INSTANCE, project=PROJECT_ID, endpoint_id=ENDPOINT_ID
        )

explain_tabular_sample_test.py:33:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
explain_tabular_sample.py:45: in explain_tabular_sample
    endpoint=endpoint, instances=instances, parameters=parameters
../../google/cloud/aiplatform_v1beta1/services/prediction_service/client.py:562: in explain
    request.instances = instances
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = endpoint: "projects/ucaip-sample-tests/locations/us-central1/endpoints/4966625964059525120"

key = 'instances'
value = [struct_value {
  fields {
    key: "petal_length"
    value {
      string_value: "1.4"
    }
  }
  fields {
    key:...    string_value: "5.1"
    }
  }
  fields {
    key: "sepal_width"
    value {
      string_value: "2.8"
    }
  }
}
]

    def __setattr__(self, key, value):
        """Set the value on the given field.

        For well-known protocol buffer types which are marshalled, either
        the protocol buffer object or the Python equivalent is accepted.
        """
        if key[0] == "_":
            return super().__setattr__(key, value)
        marshal = self._meta.marshal
        pb_type = self._meta.fields[key].pb_type
        pb_value = marshal.to_proto(pb_type, value)

        # Clear the existing field.
        # This is the only way to successfully write nested falsy values,
        # because otherwise MergeFrom will no-op on them.
        self._pb.ClearField(key)

        # Merge in the value being set.
        if pb_value is not None:
>           self._pb.MergeFrom(self._meta.pb(**{key: pb_value}))
E           TypeError: Value must be iterable

.nox/py-3-7/lib/python3.7/site-packages/proto/message.py:641: TypeError