Infinite Recursion with Jackson JSON and Hibernate JPA issue

Question

When trying to convert a JPA object that has a bi-directional association into JSON, I keep getting

org.codehaus.jackson.map.JsonMappingException: Infinite          


        

Answer 1

The point is to place the @JsonIgnore in the setter method as follow. in my case.

Township.java

@Access(AccessType.PROPERTY)
@OneToMany(fetch = FetchType.LAZY)
@JoinColumn(name="townshipId", nullable=false ,insertable=false, updatable=false)
public List<Village> getVillages() {
    return villages;
}

@JsonIgnore
@Access(AccessType.PROPERTY)
public void setVillages(List<Village> villages) {
    this.villages = villages;
}

Village.java

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "townshipId", insertable=false, updatable=false)
Township township;

@Column(name = "townshipId", nullable=false)
Long townshipId;

Answer 2

Also, using Jackson 2.0+ you can use @JsonIdentityInfo. This worked much better for my hibernate classes than @JsonBackReference and @JsonManagedReference, which had problems for me and did not solve the issue. Just add something like:

@Entity
@Table(name = "ta_trainee", uniqueConstraints = {@UniqueConstraint(columnNames = {"id"})})
@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="@traineeId")
public class Trainee extends BusinessObject {

@Entity
@Table(name = "ta_bodystat", uniqueConstraints = {@UniqueConstraint(columnNames = {"id"})})
@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="@bodyStatId")
public class BodyStat extends BusinessObject {

and it should work.

Answer 3

Also, Jackson 1.6 has support for handling bi-directional references... which seems like what you are looking for (this blog entry also mentions the feature)

And as of July 2011, there is also "jackson-module-hibernate" which might help in some aspects of dealing with Hibernate objects, although not necessarily this particular one (which does require annotations).

Answer 4

For some reason, in my case, it wasn't working with Set. I had to change it to List and use @JsonIgnore and @ToString.Exclude to get it working.

Replace Set with List:

//before
@OneToMany(mappedBy="client")
private Set<address> addressess;

//after
@OneToMany(mappedBy="client")
private List<address> addressess;

And add @JsonIgnore and @ToString.Exclude annotations:

@ManyToOne
@JoinColumn(name="client_id", nullable = false)
@JsonIgnore
@ToString.Exclude
private Client client;

Answer 5

There's now a Jackson module (for Jackson 2) specifically designed to handle Hibernate lazy initialization problems when serializing.

https://github.com/FasterXML/jackson-datatype-hibernate

Just add the dependency (note there are different dependencies for Hibernate 3 and Hibernate 4):

<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-hibernate4</artifactId>
  <version>2.4.0</version>
</dependency>

and then register the module when intializing Jackson's ObjectMapper:

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new Hibernate4Module());

Documentation currently isn't great. See the Hibernate4Module code for available options.

Answer 6

you can use DTO pattern create class TraineeDTO without any anotation hiberbnate and you can use jackson mapper to convert Trainee to TraineeDTO and bingo the error message disapeare :)