[FIXED] Spring JPA OneToOne FK as PK Cascade.Remove

Issue

I've got two tables, b and a:

• they have a one-to-one bidirectional relationship
• a has a foreign key to b that defines this relationship
• this foreign key is also considered as a primary key for a, and a JPA @ID
• I want a cascade removal that deletes the related b when a is deleted
• in MySQL, a's b_id is NOT NULL

The problem is that when I delete my A object with JPA repository, I get a ConstraintViolationException on its foreign key. I would expect that both a and b rows are deleted (cleverly starting with a's one).

How could I work around this knowing that I want to keep:

• my DB schema the same
• the cascade removal from a to b
• the b id being the JPA @Id for a

CREATE TABLE `b` (
  `dbid` int(11) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`dbid`),
);

CREATE TABLE `a` (
  `b_id` int(11) NOT NULL,
  KEY `b_fk` (`b_id`),
  CONSTRAINT `b_fk` FOREIGN KEY (`b_id`) REFERENCES `b` (`dbid`),
);

@Entity
@Table(name = "a")
public class A {

    @Id
    @Column(name = "b_id")
    @GeneratedValue(generator = "gen")
    @GenericGenerator(name = "gen", strategy = "foreign", parameters = @Parameter(name="property", value="b"))
    private Integer bId;

    @OneToOne(cascade = CascadeType.REMOVE)
    @PrimaryKeyJoinColumn
    private B b;
}

@Entity
@Table(name = "b")
public class B {

    @Id
    @GeneratedValue(strategy= GenerationType.IDENTITY)
    @Column(name = "dbid")
    private Integer id;

    @OneToOne(mappedBy = "b")
    private A a;
}

[EDIT] After all discussions in answer comments and re-reading my question, the proposals with orphanRemoval indeed are in scope and work.

Solution

If you want to delete object of B, whenever the associated A is deleted (it's the fourt point of your wishlist:

I want a cascade removal that deletes the related b when a is deleted

then you need to change your mapping in A to:

@OneToOne(cascade = CascadeType.REMOVE, orphanRemoval = true)
@PrimaryKeyJoinColumn
private B b;

Answered By - Andronicus