Jackson JSON serialization, recursion avoidance by level defining

Question

I use Jackson library for serialization of my pojo objects into JSON representation. For example I have class A and class B:

class A {
  privat         


        

Answer 1

Check the following links, it might help :

• http://wiki.fasterxml.com/JacksonFeatureBiDirReferences
• How to solve circular reference in json serializer caused by hibernate bidirectional mapping?

The only option after that would be to create your own custom module for serialization/deserialisation for your object type. see here:

• http://wiki.fasterxml.com/JacksonHowToCustomSerializers
• http://wiki.fasterxml.com/JacksonHowToCustomDeserializers

Regards.

Answer 2

For depth wise serialization, you can refer to example here https://github.com/abid-khan/depth-wise-json-serializer

Answer 3

For some cases you can limit serialization depth using a thread local integer holding max depth. See this answer.

Answer 4

If you want to limit yourself to only one level (ie : you go to the children of the current object and not further), there is a simple solution with @JsonView.

On every field that is a link to another object, annotate it with the current class as your view :

class A {
  private int id;
  @JsonView(A.class) private B b;

  constructors...
  getters and setters
}

class B {
  private int ind;
  @JsonView(B.class) private A a;

  constructors...
  getters and setters
}

Then, when serializing, use the object class as your view. Serializing an instance of A would render something like that :

{
  id: 42,
  b: {
    id: 813
  }
}

Make sure the DEFAULT_VIEW_INCLUSION is set to true, or the fields without a @JsonView annotation will not be rendered. Alternatively, you can annotate all other fields with @JsonView using the Object class, or any common super-class :

class A {
  @JsonView(Object.class) private int id;
  @JsonView(A.class) private B b;

  constructors...
  getters and setters
}

Answer 5

There is no support for level-based ignorals.

But you can get Jackson to handle cyclic references with 2.0, see for example "Jackson 2.0 released" for explanation on how to use @JsonIdentityInfo.

Answer 6

I recently encountered a similar problem: Jackson - serialization of entities with birectional relationships (avoiding cycles)

So the solution is to upgrade to Jackson 2.0, and add to classes the following annotation:

@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, 
                  property = "@id")
public class SomeEntityClass ...

This works perfectly.