Could not write content: failed to lazily initialize a collection of role

Question

I have One-To-Many relationship, here is my code

@Entity
@Table(name = \"catalog\")
public class Catalog {

    @Id
    @GeneratedValue(strategy = GenerationType         


        

Answer 1

It's caused by an infinite loop when parsing datas to JSON.

You can solve this by using @JsonManagedReference and @JsonBackReference annotations.

Definitions from API :

• JsonManagedReference (https://fasterxml.github.io/jackson-annotations/javadoc/2.5/com/fasterxml/jackson/annotation/JsonManagedReference.html) :

  Annotation used to indicate that annotated property is part of two-way linkage between fields; and that its role is "parent" (or "forward") link. Value type (class) of property must have a single compatible property annotated with JsonBackReference. Linkage is handled such that the property annotated with this annotation is handled normally (serialized normally, no special handling for deserialization); it is the matching back reference that requires special handling

• JsonBackReference: (https://fasterxml.github.io/jackson-annotations/javadoc/2.5/com/fasterxml/jackson/annotation/JsonBackReference.html):

  Annotation used to indicate that associated property is part of two-way linkage between fields; and that its role is "child" (or "back") link. Value type of the property must be a bean: it can not be a Collection, Map, Array or enumeration. Linkage is handled such that the property annotated with this annotation is not serialized; and during deserialization, its value is set to instance that has the "managed" (forward) link.

Example:

Owner.java:

@JsonManagedReference
@OneToMany(mappedBy = "owner", fetch = FetchType.EAGER)
Set cars;

Car.java:

@JsonBackReference
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "owner_id")
private Owner owner;

Another solution is to use @JsonIgnore which will just set null to the field.