ProtoField for abstract class

[srpn]

I am trying to create a @ProtoAdapter for a third party class and I couldn't find examples for usage with inheritance.
Lets say there is a class called CachedAnimal that contains an Animal and CacheDuration.

@ProtoAdapter(CachedAnimal.class)
public class CachedAnimalAdapter {
  @ProtoFactory 
  CachedAnimal create(Animal animal, String cacheDuration) {
    return new CachedAnimal(animal, cacheDuration);
  }

  @ProtoField
  Animal getAnimal(CachedAnimal cachedAnimal) {
     cachedAnimal.getAnimal();
  }
  
  @ProtoField
  String getCacheDuration(CachedAnimal cachedAnimal) {
     cachedAnimal.getDuration();
  }
}

However, this fails to compile with @AutoProtoSchemaBuilder saying the @ProtoField type "should not be abstract".

Please provide details on how to deal with abstract types and add some examples to the documentation.

[fax4ever]

Hi @srpn,
Exactly the idea of the ProtoAdapter is to generate the marshallers and the schema for class we cannot modify.
I think that you need to set the number attribute in the @ProtoField annotation.

[fax4ever]

Moreover, you should annotate the class Animal with the @ProtoFields or define a ProtoAdapter for it in turn.
Can you share more about Animal please?

[srpn]

Thanks for the response @fax4ever,
Yeah, the main question is how to add annotations to Animal and its concrete subclasses. As I mentioned, the above example with @AutoProtoSchemaBuilder fails to compile saying the @protofield type "should not be abstract".

abstract class Animal {
  String type;
}

class Dog extends Animal {
  String name;
  void bark();
  // ...
}

[fax4ever]

What would be the Protocol Buffers schema you would like to generate for this case?

[srpn]

I am looking to use Infinispan for a distributed cache and I am new to Protocol Buffers.
From what I read, oneOf could be a way to represent this as a protobuf message

Here is a full example for ease of reproducing
error: org.infinispan.protostream.annotations.ProtoSchemaBuilderException: The type com.test.Animal of field 'animal' of com.test.CachedAnimalAdapter should not be abstract.
Code used:

package com.test;

import org.infinispan.protostream.annotations.ProtoAdapter;
import org.infinispan.protostream.annotations.ProtoFactory;
import org.infinispan.protostream.annotations.ProtoField;

@ProtoAdapter(CachedAnimal.class)
public class CachedAnimalAdapter {
    @ProtoFactory
    CachedAnimal create(Animal animal, String cacheDuration) {
        return new CachedAnimal(animal, cacheDuration);
    }

    @ProtoField(number = 1)
    Animal getAnimal(CachedAnimal cachedAnimal) {
        return cachedAnimal.getAnimal();
    }

    @ProtoField(number = 2)
    String getCacheDuration(CachedAnimal cachedAnimal) {
        return cachedAnimal.getCachedTime();
    }
}

// Let's say the below classes are from a 3rd party library that I cannot annotate
class CachedAnimal {
    private Animal animal;
    private String cachedTime;

    public CachedAnimal(Animal animal, String cachedTime) {
        this.animal = animal;
        this.cachedTime = cachedTime;
    }

    public Animal getAnimal() {
        return animal;
    }

    public String getCachedTime() {
        return cachedTime;
    }
}

abstract class Animal {
    String type;

    public Animal(String type) {
        this.type = type;
    }
}

class Dog extends Animal {
    private String breed;

    public Dog(String type, String breed) {
        super(type);
        this.breed = breed;
    }

    public void makeSound() {
        System.out.println("woof");
    }
}

class Cat extends Animal {
    private String name;

    public Cat(String type, String name) {
        super(type);
        this.name = name;
    }

    public void makeSound() {
        System.out.println("meow");
    }
}

[fax4ever]

Yes! One-of seems to be the proper way to map the polymorphism.
At the moment I think that we don't support the schema generation for this case with @AutoProtoSchemaBuilder.
I'm opening an issue for it to the ProtoStream Jira => https://issues.redhat.com/projects/IPROTO.
In the meantime I think you could generate the mashallers and the proto schema manually, as we used to do.

[fax4ever]

created https://issues.redhat.com/browse/IPROTO-267