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

Using FetchType.LAZY , if still getting the error "Could not write content: failed to lazily initialize a collection of role" , that may be probably caused by somewhere in the logic (perhaps in a controller) , Catalog is being tried to be deserialized that contains list of catalog items which is a proxy but the transaction has already ended to get that. So create a new model ('CatalogResource' similar to catalog but without the list of items). Then create a catalogResource object out of the Catalog (which is returned from the query)

public class CatalogResource {
    private int catalog_id;
    private String name;
    private List<Order> orders;
} 

Answer 2

Here is my solution for this task with Hibernate. I marked hibernate releation with @JsonIgnore and use custom field for jackson, in which I check if the field is loaded. If you need serialize collection to json then you should manualy call collection getter during hibernate transaciton.

@JsonIgnore
@OneToMany(mappedBy = "myorder")
private List<OrderItem> orderItems = new ArrayList<>();

@JsonProperty(value = "order_items", access = JsonProperty.Access.READ_ONLY)
private List<OrderItem> getOrderItemsList() {

    if(Hibernate.isInitialized(this.relatedDictionary)){
        return this.relatedDictionary;
    } else{
        return new ArrayList<>();
    }
}

@JsonProperty(value = "order_items", access = JsonProperty.Access.WRITE_ONLY)
private void setOrderItemsList(List<OrderItem> orderItems) {
    this.orderItems = orderItems;
}

Answer 3

"You don't serialize in your JSON the children entities by using the com.fasterxml.jackson.annotation.JsonIgnore property"

Add @JsonIgnore for hibernate lazy loading properties eg. @ManyToOne. That should work