JAX-RS（泽西岛）创建相关对象而不是null

Question

problem is rather simple, but kinda hard to explain.

I have REST service like this:

@Path("categories")
@RequestScoped
public class CategoryResource {

    @Inject
    CategoriesFacade dao;

    @PUT
    @Consumes("application/json")
    public void putJson(Categories content) {
        System.err.println(content.toString()); // <-- ?????
        dao.edit(content);
    }

    // ....
}

And entity object like this:

@XmlRootElement
public class Categories implements Serializable {

    @Id
    @Column(name = "CATEGORY_ID", unique = true, nullable = false, precision = 5)
    private Integer categoryId;

    @Column(name = "NAME")
    private String name;

    @JoinColumn(name = "PARENT_ID", referencedColumnName = "CATEGORY_ID")
    @ManyToOne
    private Categories parentId;

    // ....    

}

Here is http request payload:

PUT http://localhost:8080/api/categories
Data: {"categoryId":"7162","name":"test","parentId":null}

And here is Categories object i get in @PUT request (see line marked with ????):

Categories{
  categoryId=7162,
  name=test,
  parentId=Categories{categoryId=null, name=null, parentId=null}
}

So as you can see here, parentId is assigned with empty Categories object, this way i'm getting ValidationException, because name could not be null.

Any idea how to make Jersey to give me this kind of object, so null value for parentId will be fine:

Categories{
  categoryId=7162,
  name=test,
  parentId=null
}

Answer 1

Stringify your object on client site (for example, if client on JavaScropt, using method JSON.stringify ).
Rest method make

@PUT
@Consumes("application/json")
public void putJson(String content) {  

And convert json string to object (for eample, using google json)

Categories cont = new com.google.gson.Gson().fromJson(content, Categories.class);