0 Replies Latest reply on Apr 19, 2017 2:58 PM by Robal

    List<Entity> to JSON

    Robal

      Dear Experts,

       

      How to convert list of entites  to Json string?

      entity1:

      @Entity

      @NamedQueries({ @NamedQuery(name = "Departament.findAll", query = "select o from Departament o"))

      @Table(name = "DEPARTMENT")

      public class Departament implements Serializable {

          @Id

          @Column(nullable = false)

          private Long id;

          @Column(length = 119)

          private String name;

       

          @OneToMany(mappedBy="department", cascade = { CascadeType.PERSIST, CascadeType.MERGE })

          private List<AccessRights> perms;

      // cut: setters and getters

       

      entity 2:

      @Entity

      @Table(name = "ACCESS_RIGHTS")

      public class AccessRights implements Serializable {

          @Id

          @Column(nullable = false)

          private Long id;

       

          @ManyToOne

          @JoinColumn(name = "ID_JEDNOSTKA")

          private Departament department;

      // cut: setters and getters

       

       

      In my main class I have executed:

              List<Departament> vl = ac.getDepartament();

              System.out.println(new Gson().toJson(vl).toString()); //error: "An attempt was made to traverse a relationship using indirection that had a null Session."

       

      The has started to orccured when I've created ManyToOne relationship. If I remove it, everything works.

      I assume that toJson method cannot be applied. If there is any relation between entities.

       

      I'm I correct? How such an issue can be resolved?

      I've tried other parsers like Objectmapper, JsonLib - no success.

       

      Best regards.