Say I have a unidirectional @ManyToOne
relationship like the following:
@Entity
public class Parent implements Serializable {
@Id
@GeneratedValue
private long id;
}
@Entity
public class Child implements Serializable {
@Id
@GeneratedValue
private long id;
@ManyToOne
@JoinColumn
private Parent parent;
}
If I have a parent P and children C1...Cn referencing back to P, is there a clean and pretty way in JPA to automatically remove the children C1...Cn when P is removed (i.e. entityManager.remove(P)
)?
What I'm looking for is a functionality similar to ON DELETE CASCADE
in SQL.
This question is related to
java
jpa
jpa-2.0
many-to-one
Use this way to delete only one side
@ManyToOne(cascade=CascadeType.PERSIST, fetch = FetchType.LAZY)
// @JoinColumn(name = "qid")
@JoinColumn(name = "qid", referencedColumnName = "qid", foreignKey = @ForeignKey(name = "qid"), nullable = false)
// @JsonIgnore
@JsonBackReference
private QueueGroup queueGroup;
@Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
Given annotation worked for me. Can have a try
For Example :-
public class Parent{
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="cct_id")
private Integer cct_id;
@OneToMany(cascade=CascadeType.REMOVE, fetch=FetchType.EAGER,mappedBy="clinicalCareTeam", orphanRemoval=true)
@Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
private List<Child> childs;
}
public class Child{
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="cct_id")
private Parent parent;
}
If you are using hibernate as your JPA provider you can use the annotation @OnDelete
. This annotation will add to the relation the trigger ON DELETE CASCADE
, which delegates the deletion of the children to the database.
Example:
public class Parent {
@Id
private long id;
}
public class Child {
@Id
private long id;
@ManyToOne
@OnDelete(action = OnDeleteAction.CASCADE)
private Parent parent;
}
With this solution a unidirectional relationship from the child to the parent is enough to automatically remove all children. This solution does not need any listeners etc. Also a JPQL query like DELETE FROM Parent WHERE id = 1
will remove the children.
Create a bi-directional relationship, like this:
@Entity
public class Parent implements Serializable {
@Id
@GeneratedValue
private long id;
@OneToMany(mappedBy = "parent", cascade = CascadeType.REMOVE)
private Set<Child> children;
}
I have seen in unidirectional @ManytoOne, delete don't work as expected. When parent is deleted, ideally child should also be deleted, but only parent is deleted and child is NOT deleted and is left as orphan
Technology used are Spring Boot/Spring Data JPA/Hibernate
Sprint Boot : 2.1.2.RELEASE
Spring Data JPA/Hibernate is used to delete row .eg
parentRepository.delete(parent)
ParentRepository extends standard CRUD repository as shown below
ParentRepository extends CrudRepository<T, ID>
Following are my entity class
@Entity(name = “child”)
public class Child {
@Id
@GeneratedValue
private long id;
@ManyToOne( fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = “parent_id", nullable = false)
@OnDelete(action = OnDeleteAction.CASCADE)
private Parent parent;
}
@Entity(name = “parent”)
public class Parent {
@Id
@GeneratedValue
private long id;
@Column(nullable = false, length = 50)
private String firstName;
}
You don't need to use bi-directional association instead of your code, you have just to add CascaType.Remove as a property to ManyToOne annotation, then use @OnDelete(action = OnDeleteAction.CASCADE), it's works fine for me.
Source: Stackoverflow.com