Question

I want to create a custom serializer in GSON that insert a key/value pair in an object, not a new object. For example, supose this:

class Car {
    @Expose
    String model;
    @Expose
    Manufacturer manufacturer;
}

class Manufacturer {
    @Expose
    String name;
    @Expose
    String from;
}

I want to get then a JSON like this:

"car":{
    "model":"beatle",
    "manufacturer":"volkswagen",
    "country":"Germany"
}

But no matter how I code the serializer, it insists to create a manufacturer object inside "car"

"manufacturer":{
    "name":"volkswagen",
    "country":"Germany"
}

How can I fix that, to get only key/value pairs?

PS: I cannot make significative changes in classes, because they are mapping the DB. It is just a example to simulate my problem.

Answer 1

I was not possible to make what I want with JsonSerializer. I could only make it works OK with the new API of GSON, since 2.1 (TypeAdapter class).

public class ManufacturerSerializer extends TypeAdapter<Manufacturer> {
    @Override
    public void write(JsonWriter out, Manufacturer m) throws IOException {
        out.value(m.getName());
        out.name("country");
        out.value(m.getFrom());
    }

    /* I only need Serialization, dont use this */
    @Override
    public Manufacturer read(JsonReader in) throws IOException {
        return null;
    }
}