Are wrapper.proto messages automatically packed / unpacked with

[Jack Wootton]

I'm using wrappers.proto in my own API that sits behind Google's Extensible Service Proxy. The proxy trans-codes JSON <-> ProtoBuf. Code for trans-coding is

https://github.com/cloudendpoints/esp/blob/ee24633d0e6837f7d7fa05302f4ea6bd419a7d8e/src/api_manager/utils/marshalling.cc#L53. For example:

Status ProtoToJson(const Message& message, std::string* result, int options) {
 ::google::protobuf::util::JsonPrintOptions json_options;
 if (options & JsonOptions::PRETTY_PRINT) {
   json_options.add_whitespace = true;
 }
 if (options & JsonOptions::OUTPUT_DEFAULTS) {
   json_options.always_print_primitive_fields = true;
 }
 // TODO: Skip going to bytes and use ProtoObjectSource directly.
 ::google::protobuf::util::Status status = ::google::protobuf::util::BinaryToJsonString( GetTypeResolver(), GetTypeUrl(message),
message.SerializeAsString(),
   result, json_options);
   return Status::FromProto(status);
 }

 

Note the call to message.SerializeAsString()

I've noticed my web client receives any wrapper messages, without their wrapper. For example, my server constructs a message 

message NumberOptions {
    google.protobuf.Int32Value minimum = 1;
    google.protobuf.Int32Value maximum = 2;
}

with the following values:

minimum {
  value: 1
}
maximum {
  value: 100
}

However, after my message passes through the ESP (and is serislised to JSON), my client receives:

minimum: 1
maximum: 100

Does SerializeAsString automatically unpack any wrapper messages? If so, can I also send JSON:

minimum: 1
maximum: 100

..and expect wrappers to be created (if the message is defined to use wrappers), i.e.

message NumberOptions {
    google.protobuf.Int32Value minimum = 1;
    google.protobuf.Int32Value maximum = 2;
}

[Josh Humphries]

It sounds like you are observing the expected behavior regarding how these wrapper types are marshalled/unmarshalled to/from JSON:

https://developers.google.com/protocol-buffers/docs/proto3#json

They get "unboxed" in JSON, as do various other well-known types such as structs, timestamps, and durations.

----
Josh Humphries
jh...@bluegosling.com

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