[FIXED] “Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements” SpringBoot

Issue

i have three entites named depense ,benifice and categories , when i want to get the benefice_C and the Depenese_C in the category entity .this error displayed to me

“Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements” SpringBoot

Depens Entities

> @Entity
@Getter
@Setter
@Table(name="depense")
public class Depense {
    
    @Id @GeneratedValue
    @Column(name = "id_etab")
    private Long idEtab;
    
     @ManyToOne
     @JoinColumn(name = "personnel_id")
    private Personnel personnel;
     @ManyToOne
     @JoinColumn(name = "CATD")
     private Categories categoriesD;

Benfice Entities

> public class Benifice {
    @Column(name = "id_etab")
    private Long idEtab;
    
     @ManyToOne
     @JoinColumn(name = "inscrit_id")
    private Inscrit inscrit;
     
     @ManyToOne
     @JoinColumn(name = "be_C")
    private  Categories benificeC;
    

Categorie entite > public class Categories implements Serializable {

    @Id  @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long idCat;
    
    @OneToMany(mappedBy = "categoriesD", fetch = FetchType.LAZY)

    private Depense depense;

    @OneToMany(mappedBy = "benificeC", fetch = FetchType.LAZY)

     private Benifice benifice;
    
    

    

Solution

Your @OneToMany mapping is not correct.

You would need a List/Set/Collection of Objects if you map OneToMany.

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long idCat;

@OneToMany(mappedBy = "categoriesD", fetch = FetchType.LAZY)
private List<Depense> depense;

@OneToMany(mappedBy = "benificeC", fetch = FetchType.LAZY)
private List<Benifice> benifice;

Answered By - I_AM__PAUL
Answer Checked By - Terry (JavaFixing Volunteer)