spring-boot-starter-data-jpa@ManyToMany collection not populating

Question

I'm getting a problem with the @ManyToMany collections not populating on data load. I've tried FetchType.LAZY and FetchType.EAGER with no changes in the result.

When I am printing the User Object the collection Object of Roles is empty.

User [userId=2, firstName=Ajay, lastName=C, [email protected], password=12345, roles=[]]

Also tried by adding referenced columns. But not worked.

Please assist in this.

User and Roles Entities as follows.

@Entity
@Table(name = "\"USER\"", schema = "\"PLATFORM_PROD_IOT\"", uniqueConstraints = {
     @UniqueConstraint(columnNames = { "\"EMAIL_ID\"" }) })
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Size(min = 1, max = 50)
    @Column(name = "\"USER_ID\"")
    private Long userId;

    @NotBlank
    @Size(min = 3, max = 50)
    @Column(name = "\"FIRST_NAME\"")
    private String firstName;

    @NotBlank
    @Size(min = 3, max = 50)
    @Column(name = "\"LAST_NAME\"")
    private String lastName;

    @NaturalId
    @NotBlank
    @Size(max = 50)
    @Email
    @Column(name = "\"EMAIL_ID\"")
    private String email;

    @NotBlank
    @Size(min = 3, max = 100)
    @Column(name = "\"PASSWORD\"")
    private String password;


    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "\"USER_ROLE_MAPPING\"", schema = "\"\PLATFORM_PROD_IOT\"", joinColumns = @JoinColumn(name = "\"USER_ID\""), inverseJoinColumns = @JoinColumn(name = "\"ROLE_ID\""))
    private Set<Role> roles = new HashSet<>();

//Getters and Setters

}

@Entity
@Table(name = "\"ROLE\"",schema="\"PLATFORM_PROD_IOT\"")
public class Role {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="\"ROLE_ID\"")
    private Long roleId;

    @Column(name="\"ROLE_NAME\"")
    private RoleName name;
//Getters and Setters
}

Answer 1

You could try this -

@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinTable(name = "\"USER_ROLE_MAPPING\"", catalog = "\"PLATFORM_PROD_IOT\"", joinColumns = { 
            @JoinColumn(name = "\"USER_ID\"", nullable = false, updatable = false) }, 
            inverseJoinColumns = { @JoinColumn(name = "\"ROLE_ID\"", 
                    nullable = false, updatable = false) })
    private Set<Role> roles = new HashSet<>();


public Set<Role> getRoles() {
    return roles;
}

public void setRoles(Set<Role> roles) {
    this.roles = roles;
}

Here I have added

1. cascade = CascadeType.ALL
2. catalog = "\"PLATFORM_PROD_IOT\"" instead of schema = "\"PLATFORM_PROD_IOT\""
3. nullable = false, updatable = false in @JoinColumn

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