Question

I have an object graph that contains objects that are (for purposes of this example) subclasses of type Foo. The Foo class has an attribute on it called bar that I do not want to be serialized with my object graph. So basically I want a way to say, whenever you serialize an object of type Foo, output everything but bar.

class Foo { // this is an external dependency
    public long getBar() { return null; } 
}

class Fuzz extends Foo {
    public long getBiz() { return null; }
}

public static void main(String[] args) {
    ObjectMapper mapper = new ObjectMapper();
    // I want to set a configuration on the mapper to
    // exclude bar from all things that are type Foo

    Fuzz fuzz = new Fuzz();
    System.out.println(mapper.writeValueAsString(fuzz));
    // writes {"bar": null, "biz": null} what I want is {"biz": null}
}

Thanks,
Ransom

Edit: Used StaxMan suggestion, including code that I would end up using (and made bar a getter for example’s sake)

interface Mixin {
    @JsonIgnore long getBar();
}

class Example {
    public static void main() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.getSerializationConfig().addMixInAnnotations(Foo.class, Mixin.class);
        Fuzz fuzz = new Fuzz();
        System.out.println(mapper.writeValueAsString(fuzz));
        // writes {"biz": null} whoo!
    }
} 

Answer 1

Aside from @JsonIgnore or @JsonIgnoreProperties (esp. via Mix-in Annotations), you can also define specific types to be globally ignored with ‘@JsonIgnoreType’. For third-party types, this too can be applied as a mix-in annotation.