Pylance-release: Pylance type checking rejects gRPC protobuf generated types

[adriangay]

Environment data

Language Server version: Python 2020.8.106424 (2 September 2020); Pylance 2020.9.0 (3 September 2020)

OS and version: OSX 10.14.6 (18G84)

Python version (& distribution if applicable, e.g. Anaconda): 3.8.5 64-bit

Expected behaviour

Pylance type checking should accept gRPC tools generated protobuf types in type hints

Actual behaviour

Pylance reports Expected class type but received "GeneratedProtocolMessageType"

Code Snippet / Additional information

Here is the gRPC tools generated type definition in a _pb2.py file:

Content = _reflection.GeneratedProtocolMessageType('Content', (_message.Message,), {
  'DESCRIPTOR' : _CONTENT,
  '__module__' : 'proto.tagging_service_pb2'
  # @@protoc_insertion_point(class_scope:com.example.map.Content)
  })
_sym_db.RegisterMessage(Content)

MLTags = _reflection.GeneratedProtocolMessageType('MLTags', (_message.Message,), {
  'DESCRIPTOR' : _MLTAGS,
  '__module__' : 'proto.tagging_service_pb2'
  # @@protoc_insertion_point(class_scope:com.example.map.MLTags)
  })
_sym_db.RegisterMessage(MLTags)

Here is a reference in a method signature:

from proto.tagging_service_pb2 import MLTags, Content

        def EnrichContentWithTags(self, request: Content, context: ServicerContext) -> MLTags:

Here is the Pylance type-checking message:

[erictraut]

The protoc tool generates Python that is not friendly to type checkers. For that reason, there's a protoc plugin that generates high-quality type stubs for proto files. It's called mypy-protobuf, and you can install it via pip.

Despite the fact that "mypy-protobuf" contains "mypy" in its name, it's not specific to mypy. It outputs standard type definition files that are understandable by all standards-compliant type checkers including Pyright, which is the type checker at the heart of Pylance.

When you generate the "_pb2.py" file, you should also generate the corresponding "_pb2.pyi" file as follows:

protoc -I. --python_out=. --grpc_python_out=. __mypy_out=. <filename.proto>

[adriangay]

thanks... this fixed my issue