update data in database with specific condition in spring boot

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I am trying to update list of data that is foreignkey in another table.

Scenario:

I have class A:

public class A{
    @javax.persistence.Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    
    private String name;
    
    
    @OneToMany(mappedBy = "A", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    private List<B> b;
}

i have also another class B:

public class B  {
    @javax.persistence.Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    
    private String name;
    
    @ManyToOne(fetch = FetchType.EAGER, optional = false)
    @JoinColumn(name = "a_id", nullable = false)
    private A a;
}

My goal is: to update list of b in perfect way.

Example:

i have this id list for table B :

id name a_id
1 n1 1
2 n2 1
3 n3 1
4 n4 2
5 n5 1
6 n6 3

I have this list to update :

[n3,n9,n2,n7,n8]

this list must be updated for a_id = 1 so in this case i have 2 things to do:

first : adding n7, n8, n9 (with a_id = 1)
second: remove n1, n5 (because they are not included in the list above)

My expected output :

id name a_id
2 n2 1
3 n3 1
4 n4 2
6 n6 3
7 n7 1
8 n8 1
9 n9 1

How can we achieve this result in the best way?

spring-data-jpa spring-boot hibernate spring java
1 Answers

Use the following mapping and just merge/save the A entity, and Hibernate will take care of removing/persisting/updating.

public class A {
    @javax.persistence.Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    
    private String name;
    
    @OneToMany(orphanRemoval = true, cascade = CascadeType.ALL)
    @JoinColumn(name = "a_id", nullable = false)
    private List<B> b;
}

public class B {
    @javax.persistence.Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    
    private String name;
}

If you want to keep the a association in B, then you will have to do the persist/update/remove manually, by calling EntityManager.persist/EntityManager.merge/EntityManager.remove respectively for the various B entities.

user_4124460
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