@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

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.