JAX-RS Jersey JSON preserves null using annotations

Question

How to get JAXB to keep zeros when receiving a JSON sting that contains a null or "" value.

String {"id":null,"fname":"John","region":""}

returns an object:

  Person { Integer id = 0 String fname = "John" Region regions = 0 } 

I would like it to return null instead of 0

Here is what I still have:

 @Provider public class JAXBContextResolver implements ContextResolver<JAXBContext> { private JAXBContext context; private Class<?>[] types = {Person.class}; public JAXBContextResolver() throws Exception { this.context = new JSONJAXBContext(JSONConfiguration.natural().build(), types); } public JAXBContext getContext(Class<?> objectType) { for (Class<?> c : types) { if (c.equals(objectType)) { return context; } } return null; } } 

Person.class annotated with @XmlRootElement I tried to look at Jackson's annotations but was unsuccessful.

Answer 1

Note. I am an EclipseLink JAXB (MOXy) and a member of the JAXB Group (JSR-222) .

The following is an example of how this can be done using MOXy.

Person

MOXy will disable the Person object as you want, without specifying any metadata. To make the output JSON contain null values, you can use the annotation @XmlElement(nillable=true) (see binding to JSON and XML - processing a null value ).

 package forum8748537; import javax.xml.bind.annotation.*; @XmlAccessorType(XmlAccessType.FIELD) public class Person { @XmlElement(nillable=true) Integer id; @XmlElement(nillable=true) String fname; @XmlElement(nillable=true) Region regions; } 

jaxb.properties

To specify MOXy as your JAXB provider (JSR-222), you need to add a file named jaxb.properties in the same package as the domain classes, with the following entry (see Specifying EclipseLink MOXy as a JAXB Provider ).

 javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory 

Demo

 package forum8748537; import java.io.StringReader; import java.util.*; import javax.xml.bind.*; import javax.xml.transform.stream.StreamSource; public class Demo { public static void main(String[] args) throws Exception { Map<String, Object> properties = new HashMap<String, Object>(2); properties.put("eclipselink.media-type", "application/json"); properties.put("eclipselink.json.include-root", false); JAXBContext jc = JAXBContext.newInstance(new Class[] {Person.class}, properties); StringReader json = new StringReader("{\"id\":null,\"fname\":\"John\",\"region\":\"\"}"); Unmarshaller unmarshaller = jc.createUnmarshaller(); Person person = unmarshaller.unmarshal(new StreamSource(json), Person.class).getValue(); Marshaller marshaller = jc.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); marshaller.marshal(person, System.out); } } 

Exit

 { "id" : null, "fname" : "John", "regions" : null } 

Using MOXy in a JAX-RS Application

An example of using MOXy in a JAX-RS application:

• MOXy as your JAX-RS JSON provider - server side
• MOXy as a JAX-RS JSON Provider - Client Side

Answer 2

Like JSON-B JSR-367 (JAX-RS 2.1 JSR-370), the following annotation works instead of @XmlElement.

 @JsonbProperty(nillable = true)