Does Protobuf JavaLite support google.protobuf.Struct / google.protobuf.Value?

Question

Here is the proto message that we trying to send.

message Cta {
  string title = 1;
  string pid = 2;
  google.protobuf.Struct params = 3;
}

• Does protobuf-lite library which is recommended for android support google.protobuf.Struct?

• Where can we find the list of known proto types that are supported by the javalite runtime for protobuf?

• If in case Struct / Vaule is not supported by the java-lite then what is recommended proto type for HashMap<String, Object> ?

Gradle that we using to generate the java code from proto.

plugins {
    id 'com.android.library'
    id 'kotlin-android'
    id 'com.google.protobuf'
    id 'org.jetbrains.kotlin.android'
}

java {
    sourceCompatibility = JavaVersion.VERSION_1_7
    targetCompatibility = JavaVersion.VERSION_1_7
}

android {
    compileSdkVersion 33
    buildToolsVersion "30.0.3"
    namespace 'com.boom.protobuf'

}

protobuf {
    protoc {
        artifact = "com.google.protobuf:protoc:3.20.1"
    }

    generateProtoTasks {
        all().each { task ->
            task.builtins {
                java {
                    option 'lite'
                }
                kotlin {
                    option 'lite'
                }
            }
        }
    }
}

dependencies {
    api 'com.google.protobuf:protobuf-kotlin-lite:3.23.0'
    api 'com.google.protobuf:protobuf-javalite:3.23.0'
}

Answer 1

Going after the documentation of the Protobuf Java Lite runtime, I found some answers for your first and second topics. What you want is in the MessageLite interface.

Does protobuf-lite library which is recommended for android support google.protobuf.Struct?

Yes. You can see from the "All Known Implementing Classes" that Struct and Value implement the MessageLite interface. Meaning that they're available in that runtime level.

Where can we find the list of known proto types that are supported by the javalite runtime for protobuf?

That list of "All Known Implementing Classes" is the closest thing I found for you.

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The thing is that this might not solve your problem. Protobuf requires you to define the structure you want to serialize. That being said, if you don't want to define it beforehand, you'll need to handle it yourself. One option is to use JSON (or any other serialization format) to serialize the Object and inject it into your message as a raw value.