Hibernate: Cascade Type

Question

Let's I have entity A and entity B. Entity A have @OneToOne relationship with B.
I want do next:
if I remove A then B must be removed also.
If I remove B then A isn't removed.

In which entity I must set

@OneToOne(cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})

and in which side I must set

@OneToOne(cascade = {CascadeType.ALL})

?

score 33 · Accepted Answer · answered May 11 '12 at 12:46

33

The cascade from A to B should be placed on the field referencing B in class A, the cascade from B to A should be placed on the field referencing A in class B.

public class A {
    @OneToOne(cascade = {CascadeType.ALL})
    B b;
}

Should be in class A, as you want every action to be cascaded to B.

public class B {
    @OneToOne(cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})
    A a;
}

Should be in class B, as you only want certain actions cascaded to A

answered May 11 '12 at 12:46

Lukazoid

19,016
3
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What is the rational behind the use of `CascadeType.MERGE`, `CascadeType.PERSIST` and `CascadeType.REFRESH`? – Grégoire C Jun 19 '15 at 12:43
1

@geceo Because they are the cascades the asker was asking for :p [here](http://docs.jboss.org/hibernate/stable/core/manual/en-US/html/objectstate.html#objectstate-transitive) is an explanation of the different cascade options, basically these options are the same as `CascadeType.ALL` but without `REMOVE` or `DETACH` as the asker did not want these to be applied automatically to A when they are applied to B. – Lukazoid Jul 09 '15 at 10:52

score 3 · Answer 2 · answered May 11 '12 at 12:42

3

if A "has" B, then you must define CascadeType.ALL in A:

public class A {
  // changes to A cascade to B
  @OneToOne(cascade = {CascadeType.ALL})
  B b
}

answered May 11 '12 at 12:42

heikkim

2,955
2
24
34

score 0 · Answer 3 · answered May 11 '12 at 13:04

If Class A has Class B then CascadeType.ALL will be appiled on B. then

Public Class A
{
  Private B b;
  @OneToOne(cascade = CascadeType.ALL)   
  public B getB() {       
    return this.b;   
   }     
  public void B(B b) {         
    this.b = b;   
  }
}

for more read this example

Hibernate: Cascade Type

3 Answers3

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