Simpler way to delete JPA mapped tables records - sql

Question

Is there any simpler way to delete the records of table with are mapped by #OneToMany and #ManyToOne JPA mapping. Currently I am using PostgreSQL as my database. There are 1000 records ranging from 0 to 999 which I want to delete, and rest I want to keep. As deleting every record with deletion of there references(foreign key) will be very hectic. Just want a simpler way to do this.

Answer 1

You can always execute a DELETE query in JPA:
int rowsDeleted = entityManager
.createQuery("DELETE FROM MyEntity WHERE id >= 0 AND id <=999")
.executeUpdate();
If there are foreign keys, you need some extra work:
int childRowsDeleted = entityManager
.createQuery("DELETE FROM MyChildEntity WHERE parent.id >= 0 AND parent.id <=999")
.executeUpdate();
int rowsDeleted = entityManager
.createQuery("DELETE FROM MyEntity WHERE id >= 0 AND id <=999")
.executeUpdate();
If there are many foreign keys, perhaps you can consider JPA cascade remove:
#OneToOne(cascade={CascadeType.REMOVE})
and then entityManager.remove() each entity but this will have performance implications since you will end up with many DELETE queries, each deleting a single row.

Answer 2

Got this with introducing #DeleteMapping, and it worked without even using
" #OnDelete(action = OnDeleteAction.CASCADE)" this annotation above the mapped variable declaration in the child class
[https://www.callicoder.com/hibernate-spring-boot-jpa-one-to-many-mapping-example/#get-paginated-posts-get-postspage0size2sortcreatedatdesc], We can follow this link to get a complete overview.
#DeleteMapping("/posts/{postId}")
public ResponseEntity<?> deletePost(#PathVariable Long postId) {
return postRepository.findById(postId).map(post -> {
postRepository.delete(post);
return ResponseEntity.ok().build();
}).orElseThrow(() -> new ResourceNotFoundException("PostId " + postId + " not found"));
}