Lets say I have JSON of the following format:
{
"type" : "Foo"
"data" : {
"object" : {
"id" : "1"
"fizz" : "bizz"
...
},
"metadata" : {
...
},
"owner" : {
"name" : "John"
...
}
}
}
I am trying to avoid custom deserializer and attempting to deserialize the above JSON (called Wrapper.java) into Java POJOs. The "type" field dictates the "object" deserialization ie. type = foo means the deserialize the "object" field using the Foo.java. (if type = Bar, use Bar.java to deserialize the object field). Metadata/owner will always deserialize the same way using a simple Jackson annotated Java class for each. Is there a way to accomplish this using annotations? If not, how can this be done using a custom deserializer?
Annotations-only approach
Alternatively to the custom deserializer approach, you can have the following for an annotations-only solution (similar to the one described in Spunc's answer, but using type as an external property):
public abstract class AbstractData {
private Owner owner;
private Metadata metadata;
// Getters and setters
}
public static final class FooData extends AbstractData {
private Foo object;
// Getters and setters
}
public static final class BarData extends AbstractData {
private Bar object;
// Getters and setters
}
public class Wrapper {
private String type;
@JsonTypeInfo(use = Id.NAME, property = "type", include = As.EXTERNAL_PROPERTY)
@JsonSubTypes(value = {
@JsonSubTypes.Type(value = FooData.class, name = "Foo"),
@JsonSubTypes.Type(value = BarData.class, name = "Bar")
})
private AbstractData data;
// Getters and setters
}
In this approach, @JsonTypeInfo is set to use type as an external property to determine the right class to map the data property.
The JSON document can be deserialized as following:
ObjectMapper mapper = new ObjectMapper();
Wrapper wrapper = mapper.readValue(json, Wrapper.class);