JSON Jersey Auto serialization Wrapper Problems

Question

I have a POJO

public class Graph {
    public int v;
    public int e;
}

and a very simple service

@Service("graph-service#default")
public class DefaultGraphService implements GraphService {
    public Response createGraph(Graph graph) {
        return Response.ok().build();
    }
}

which implements a very simple interface

@Path( "graph-service" )
public interface GraphService {

    @Path( "create-graph" )
    @POST
    @Consumes(MediaType.APPLICATION_JSON)
    public Response createGraph(Graph graph);
}

I have a simple spring-context.xml set up as follows

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:jaxrs="http://cxf.apache.org/jaxrs"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/context 
       http://www.springframework.org/schema/context/spring-context-3.0.xsd
       http://cxf.apache.org/jaxrs
       http://cxf.apache.org/schemas/jaxrs.xsd">

    <import resource="classpath:META-INF/cxf/cxf.xml"/>
    <import resource="classpath:META-INF/cxf/cxf-servlet.xml"/>

    <context:annotation-config/>
    <context:component-scan base-package="me.jamesphiliprobinson.graphs"/>

    <jaxrs:server id="testServices" address="/testServices">
        <jaxrs:serviceBeans>
            <ref bean="graph-service#default"/>
        </jaxrs:serviceBeans>
        <jaxrs:providers>
            <ref bean="jsonProvider"/>
        </jaxrs:providers>
    </jaxrs:server>
    <bean id="jsonProvider" class="org.codehaus.jackson.jaxrs.JacksonJsonProvider" />
</beans>

If I spin the service up in tomcat it works fine can I can curl an object like

{"v":2,"e":1}

Without any difficulty. However, if I run this test

@Test
public void testCreateGraph() {
    UncertaintyGraphService service =
            JAXRSClientFactory.create( "http://localhost:" + port + "/" + getRestServicesPath() + "/testServices/",
                                       GraphService.class );
    Graph graph = new Graph();
    graph.e = 1;
    graph.v = 2;
    Response result = service.createGraph(graph);
    assertNotNull(result);
}

Then it fails as there is

No message body writer has been found for class : class me.jamesphiliprobinson.graphs.Graph, ContentType : application/json

If I add an

@XmlRootElement

to the POJO then the service serializes the graph object but seems to send

{"graph":{"e":1,"v",2}}

Instead which I can see making sense but the deserialization seems to still expect

{"e":1,"v":2}

As I get the error

WARNING: WebApplicationException has been caught : Unrecognized field "graph" (Class me.jamesphiliprobinson.graphs.Graph), not marked as ignorable

I'm surely missing something incredibly simple. I would prefer for the items to serialise to

{"v":2,"e":1}

But if they will deserialise correctly I can live with a root element. ie

{"graph":{"v":2,"e":1}}

Answer 1

See where you are registering the JacksonJsonProvider on the server?

<bean id="jsonProvider" class="org.codehaus.jackson.jaxrs.JacksonJsonProvider" />

This is to handle JSON (de)serizalization to/from POJO on the server side. But the client needs the same support. You can use the overloaded

• JAXRSClientFactory.create(String baseAddress, Class<T> cls, List<?> providers)

to register the provider on the client side. Just add the JacksonJsonProvider to the List of providers .

JAXRSClientFactory.create(baseUri, Service.class, Arrays.asList(new JacksonJsonProvider())