CODEWITHSUNDEEP
javajsonjaxbjax-rs
anil keshav
anil keshav

Reputation: 489

JSON to java unmarshelling in JAX-RS returning { } in POST

I am trying to build a JAX-RS rest api that accepts in the POST method a (JSON) UnMarshelled class and at the moment i am only returning the same class (marshelled back as a JSON).

When I return the object i am getting a plain { } in the browser(postman client). I am using the data provided in this question:.

Is my understanding correct that the same JSON that i am sending should come back as it is ?, if yes not sure why is only { } being received or have i completely missed something.

Below is my code :

@Path("/metadata") public class MetadataResource {

//Anil: This is the method that will be called when a post at /metadata comes  
@Consumes(MediaType.APPLICATION_JSON)
@POST
@Produces(MediaType.APPLICATION_JSON)
public ObjectA CreateMetadata_JSON(ObjectA metadata) {

    return metadata;

}

Class Object A:

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "objectA")
public class ObjectA {
    @XmlElement(required = true)
    protected String propertyOne;
    @XmlElement(required = true)
    protected String propertyTwo;
    @XmlElement(required = true)
    protected ObjectB objectB;
}

and Class Object B:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "objectB")
public class ObjectB {
    @XmlElement(required = true)
    protected String propertyA;
    @XmlElement(required = true)
    protected boolean propertyB;
}

The json object being sent is :

{ 
  "objectA" : 
  { 
    "propertyOne" : "some val", 
    "propertyTwo" : "some other val",
    "objectB" : 
    {
      "propertyA" : "some val",
      "propertyB" : "true" 
    }
  }
}

Upvotes: 0

Views: 113

Answers (1)

Paul Samsotha
Paul Samsotha

Reputation: 208994

It's because of the root object wrapper

{ 
  "objectA" : 
  
}

Generally the expected JSON object is everything you have, excluding the above root value wrapper. If there is a requirement to use the JSON exactly how you have it, then the JSON provider needs to be configured to un-wrap the root value. If you don't, then the provider doesn't recognize any properties in the JSON, and you are left with an object with a bunch of nulls. So when you serialize the same object, the provider ignores the null, and you are left with an empty JSON object { }.

So the simple solution is to just use

{ 
  "propertyOne" : "some val", 
  "propertyTwo" : "some other val",
  "objectB" : 
  {
    "propertyA" : "some val",
    "propertyB" : "true" 
  }
}

If you require the root value wrapper, then I would need to know what JSON provider you are using, before I can try and help with how you can configure it to unwrap the root value.

UPDATE

For MOXy, if you want to configure it to wrap/unwrap the root value, you can setIncludeRoot to true, in the MoxyJsonConfig. You will need to provide a ContextResolver for it to be discovered.

@Provider
public class MoxyConfigResolver implements ContextResolver<MoxyJsonConfig> {
    
    private final MoxyJsonConfig config;
    
    public MoxyConfigResolver() {
        config = new MoxyJsonConfig();
        config.setIncludeRoot(true);
    }

    @Override
    public MoxyJsonConfig getContext(Class<?> type) {
        return config;
    } 
}

Upvotes: 1

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