What is the meaning of the CascadeType.ALL for a @ManyToOne JPA association

java jpa one-to-many cascade many-to-one
forhas picture forhas · Oct 23, 2012 · Viewed 330.7k times · Source

I think I misunderstood the meaning of cascading in the context of a @ManyToOne relationship.

The case:

public class User {

   @OneToMany(fetch = FetchType.EAGER)
   protected Set<Address> userAddresses;

}

public class Address {

   @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
   protected User addressOwner;

}

What is the meaning of the cascade = CascadeType.ALL? For example, if I delete a certain address from the database, how does the fact that I added the cascade = CascadeType.ALL affect my data (the User, I guess)?

Answer

kostja picture kostja · Oct 23, 2012

The meaning of CascadeType.ALL is that the persistence will propagate (cascade) all EntityManager operations (PERSIST, REMOVE, REFRESH, MERGE, DETACH) to the relating entities.

It seems in your case to be a bad idea, as removing an Address would lead to removing the related User. As a user can have multiple addresses, the other addresses would become orphans. However the inverse case (annotating the User) would make sense - if an address belongs to a single user only, it is safe to propagate the removal of all addresses belonging to a user if this user is deleted.

BTW: you may want to add a mappedBy="addressOwner" attribute to your User to signal to the persistence provider that the join column should be in the ADDRESS table.

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