How to convert from Json to Protobuf?

Question

I'm new to using protobuf, and was wondering if there is a simple way to convert a json stream/string to a protobuf stream/string in Java?

For example,

protoString = convertToProto(jsonString)

I have a json string that I want to parse into a protobuf message. So, I want to first convert the json string to protobuf, and then call Message.parseFrom() on it.

Thanks in advance for the help!

Answer 1

With proto3 you can do this using JsonFormat. It parses directly from the JSON representation, so there is no need for separately calling MyMessage.parseFrom(...). Something like this should work:

JsonFormat.parser().merge(json_string, builder);

Answer 2

//You can use this for converting your input json to a Struct / any other Protobuf Class    

import com.google.protobuf.Struct.Builder;
import com.google.protobuf.Struct;
import com.google.protobuf.util.JsonFormat;
import org.json.JSONObject;

JSONObject parameters = new JSONObject();

Builder structBuilder = Struct.newBuilder();
JsonFormat.parser().merge(parameters.toString(), structBuilder);

// Now use the structBuilder to pass below (I used it for Dialog Flow V2 Context Management)