CODEWITHSUNDEEP
hibernatemany-to-many
Craig
Craig

Reputation: 1345

Hibernate ManyToMany Configuration

I have a bit of a complicated structure that I have listed below. Basically I have a bunch of different "role groups". Each role group contains a group of roles. A user can potentially have several different role groups, and a role group can be applied to many different users. Because of that I went with a ManyToMany relationship.

I want the RoleGroup to be part of the User, as listed below.

Everything is somewhat working. However, when I use the insert statements listed below I have a bug in my code. The RoleGroup contains only ROLE3. I am not sure why but somehow my code is only allowing one Role to be part of a RoleGroup with the current setup. Querying the database yields that all 3 Roles are present, but they are not on my Entity.

Please help!

CREATE TABLE USER (
    USER_ID   NUMBER(38, 0) PRIMARY KEY,
    NAME      VARCHAR2(50) NOT NULL
);

CREATE TABLE ROLE_GROUPS (
    ROLE_GROUP_ID   NUMBER(38, 0) PRIMARY KEY,
    NAME            VARCHAR2(50) NOT NULL
    -- constraints
    CONSTRAINT UQ_ROLE_GROUP_NAME UNIQUE (NAME)
);

CREATE TABLE ROLE (
    ROLE_GROUP_ID   NUMBER(38, 0) NOT NULL,
    ROLE            VARCHAR2(10) NOT NULL,
    -- constraints
    CONSTRAINT PK_ROLES PRIMARY KEY (ROLE_GROUP_ID, ROLE),
    CONSTRAINT FK_ROLES FOREIGN KEY(ROLE_GROUP_ID) REFERENCES ROLE_GROUPS
);

CREATE TABLE ROLE_GROUP_X_USER (
    ROLE_GROUP_ID   NUMBER(38, 0) NOT NULL,
    USER_ID         NUMBER(38, 0) NOT NULL,

    -- constraints
    CONSTRAINT PK_1 PRIMARY KEY (ROLE_GROUP_ID, USER_ID),
    CONSTRAINT FK_1 FOREIGN KEY(ROLE_GROUP_ID) REFERENCES ROLE_GROUPS,
    CONSTRAINT FK_1 FOREIGN KEY(USER_ID) REFERENCES USER
);

INSERT INTO ROLE_GROUPS(ROLE_GROUP_ID, NAME) VALUES (1, 'GROUP_1');
INSERT INTO ROLE(ROLE_GROUP_ID, NAME) VALUES(1 ,'ROLE1');    
INSERT INTO ROLE(ROLE_GROUP_ID, NAME) VALUES(1 ,'ROLE2');    
INSERT INTO ROLE(ROLE_GROUP_ID, NAME) VALUES(1 ,'ROLE3');    
INSERT INTO ROLE_GROUP_X_USER(USER_ID,ROLE_GROUP_ID) SELECT USER_ID, 1 FROM USER where USER_ID IN ('1', '2', '3', '4');

@Entity
@Table(name="USER")
public class User {
   //Other code

   @ManyToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER)
   @JoinTable(name = "ROLE_GROUP_X_USER", 
   joinColumns = { @JoinColumn(name = "USER_ID") }, 
   inverseJoinColumns = { @JoinColumn(name = "ROLE_GROUP_ID") })
   private Set<RoleGroupEntity> roleGroupEntities;
}

@Entity
@Table(name="ROLE_GROUPS")
public class RoleGroupEntity {
   //Other code

   @ElementCollection(fetch=FetchType.EAGER)
   @CollectionTable(name="ROLE", joinColumns=@JoinColumn(name="ROLE_GROUP_ID"))
   @AttributeOverrides({
   @AttributeOverride(name="role", column=@Column(name="ROLE")) })
   private Set<Role> roles = new HashSet<Role>();
}


@Embeddable
public class Role {
    private String role;
    //Getter, Setter
    //Hashcode, equals override
}

Upvotes: 4

Views: 452

Answers (1)

Jason Huntley
Jason Huntley

Reputation: 3877

It looks like your joinColumn is wrong. Usually you have two columns on a ManyToMany Join, joinColumns and inverseJoinColumns, but I'd have to say you're using the wrong column.

I think you're going to need a separate mapping table for including roles in groups. Add this to your RolesGroup class:

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "GROUP_ROLE_MAP_T", joinColumns = {
        @JoinColumn(name = "ROLE_GROUP_ID")
}, inverseJoinColumns = {
        @JoinColumn(name = "ROLE_ID")
})
private Set<Role> role = new HashSet<Role>(0);

Make your roles a table too:

@Entity
@Table(name = "ROLES_T")
@AttributeOverride(name = "id", column = @Column(name = "ROLE_ID"))
public class Role {
    @Column(name = "ROLE_ID", nullable = true)
    private Long roleId = new Long(0);

    @Column(name = "ROLE_NAME", nullable = false)
    private String role;
}

Don't forget your getter/setters.

Upvotes: 1

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