Example of Polymorphic Deserialization using Jackson

Polymorph.java

import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import com.fasterxml.jackson.databind.annotation.JsonNaming;


@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")
@JsonSubTypes({
    @JsonSubTypes.Type(value=AudioAttachment.class, name="audio"),
    @JsonSubTypes.Type(value=LinkAttachment.class, name="link")
})
public class Attachment {

}

@JsonNaming(PropertyNamingStrategy.LowerCaseWithUnderscoresStrategy.class)
public class Audio {
    public int aid;
    public int ownerId;
}

public class AudioAttachment extends Attachment {
    public Audio audio;
}

public class Link {
    public String url;
    public String title;
}

public class LinkAttachment extends Attachment {
    public Link link;
}

Hi,

Thanks for this very clear example.
Do you know if this could work if the SubTypes are in different Maven projects ?

i.e: Audio, AudioAttachment and Link are each inside a different Maven project than Attachment.

I have a problem with circular dependency and can't figure a way out of it.
Thanks

Could you please give an example of Custom Deserializer for Object Composition.

public class Parent{

 String p_memeber1;
 String p_memeber2;
 CompClass1  comp1;
 CompClass2 comp2;

...
..
}

public Class CompClass1{
String comp1_member1;
String comp1_member2;
SubCompClass1 subCom1;
...
...
}

public Class CompClass2{
String comp2_member1;
String comp2_member2;
SubCompClass2 subCom2;
...
...
}

I want the json String to be deserialize into a Parent Object with all the nested objects details populated as well.

Here is a good article describing how to deal with Polymorphism and Jackson Deserialization: https://octoperf.com/blog/2018/02/01/polymorphism-with-jackson/

Excellent tutorial!