Conformance failure: proto2 + JSON + extension

[tbkka]

This popped up on a CI bot:

CONFORMANCE TEST BEGIN ====================================

ERROR, test=Recommended.Proto2.JsonInput.FieldNameExtension.Validator: Expected JSON payload but got type 1. request=json_payload: "{\n "[protobuf_test_messages.proto2.extension_int32]": 1\n }" requested_output_format: JSON message_type: "protobuf_test_messages.proto2.TestAllTypesProto2" test_category: JSON_TEST, response=parse_error: "JSON failed to parse: unknownField("[protobuf_test_messages.proto2.extension_int32]")"

[thomasvl]

I sent some email looking for more info on proto2 extension support in JSON.

[tbkka]

Let me know what you find. I just pushed up a draft PR #1002 which is based on the design for TextFormat and the contents of the new conformance test. It still needs a little work before I'm happy merging it, but it's enough to at least pass that test.

[thomasvl]

So far what I've been able to piece together:

Python has some support and tests that include extensions:

• https://github.com/protocolbuffers/protobuf/blob/master/python/google/protobuf/json_format.py
• https://github.com/protocolbuffers/protobuf/blob/master/python/google/protobuf/internal/json_format_test.py

And Go seems to (didn't hunt down their impl, just found a reference to the test):

• https://github.com/golang/protobuf/blob/e9dc0d72c1a35f349f6d6871842199ddaaaf9edc/jsonpb/json_test.go#L317

[tbkka]

Thanks, Thomas! Those seem to verify what I guessed from the conformance test. Extensions are handled essentially the same as in TextFormat: The key name is surrounded by [] to mark it as an extension field name, but otherwise the coding is the same as regular JSON.

I think that's enough detail to finish up #1002 and get this landed.

[tbkka]

Fixed via #1002