xpath like query for protobuf messages

Question

I am looking for a xpath like query language for protobuf messages. For example, for the Person message shown below [ borrowed from the Developer guide ]

message Person {
  required string name = 1;
  required int32 id = 2;
  optional string email = 3;

  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }

  message PhoneNumber {
    required string number = 1;
    optional PhoneType type = 2 [default = HOME];
  }

  repeated PhoneNumber phone = 4;
}

I would like to have methods like

XPBQuery.get(person, "$.id") ==> returns the id
XPBQuery.get(person, "$.name") ==> returns the name
XPBQuery.get(person, "$.phone.number[0]") ==> returns the first phone number

One way is to convert the proto to Json and use a JsonPath/JsPath API's. But it may be expensive to convert to Json everytime especially for large Proto objects.

Any help is much appreciated.

Thanks, Irfan

Answer 1

Support for that is coming in protobuf v3: https://github.com/google/protobuf/blob/4644f99d1af4250dec95339be6a13e149787ab33/src/google/protobuf/field_mask.proto