@JsonIgnore and @JsonBackReference are being Ignored

Question

I'm working with RestEasy, Jboss 7 and EJB 3.1. I'm creating a RESTful web service that returns data in JSON format.

The problem is that I have a @ManyToOne relationship on one of my entities which causes an infinite recursion during serialization. I tried using Jackson's @JsonIgnore and @JsonBackReference annotations to fix the problem but it seems as if they are being totally ignored and the infinite recursion is still occurring.

This is my User Class:

class User {
    private String userId;
    private Role role;

    @Id
    @Column(name = "\"UserId\"", unique = true, nullable = false, length = 30)
    public String getUserId() {
        return this.UserId;
    }

    public void setUserId(String UserId) {
        this.UserId = UserId;
    }

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "\"RoleId\"", nullable = false)
    //I have tried @JsonIgnore without @JsonBackReference 
    @JsonIgnore
    //I have tried @JsonBackReference without @JsonIgnore 
    //Also I have tried @JsonBackReference and @JsonIgnore together
    @JsonBackReference("role-User")
    public Role getRole() {
        return this.role;
    }
}

This is a part of my Role Class:

@JsonManagedReference("role-User")
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "role")
public Set<User> getUsers() {
    return this.users;
}

I have read somewhere that I should register Jackson with my application to be able to use regular Jaxb annotation so I created a class

@Provider
@Produces(MediaType.APPLICATION_JSON)
public class JacksonContextResolver implements ContextResolver<ObjectMapper> {
    public JacksonContextResolver() {
        ObjectMapper mapper = new ObjectMapper();
        AnnotationIntrospector introspector = new JaxbAnnotationIntrospector();

        mapper.getDeserializationConfig().setAnnotationIntrospector(
                introspector);
        mapper.getSerializationConfig().setAnnotationIntrospector(introspector);
    }

    public ObjectMapper getContext(Class<?> objectType) {
        return objectMapper;
    }
}

The problem with the above being that JaxbAnnotationIntrospector() is deprecated.

Please:

• Do you have any idea why the Jackson annotations are being ignored?
• How can I use the regular JAXB XML annotations instead of Jackson's?
• What can I use instead of JaxbAnnotationIntrospector()?

An answer to any of these question is appreciated, thanks.

Update:

For now I have excluded resteasy-jackson-provider using jboss-deployment-structure.xml and I am using Jettison instead. I still want to know how could I use Jackson!

Answer 1

I had a similar problem where my getter function was not named based on the field name, so the json parsing was still happening for the getter. Changing the getter name solved the issue.

Answer 2

The problem here seems to be related to using Set<User> instead of List<User>. I had exactly the same problem and changing from Set<User> to List<User> fixed this, otherwise I always got Infinite recursion error from Jackson. I don't know if this is really a bug in Jackson or do you have to provide some other annotations etc. when using Set.