Is there any use for Spring Data JPA's @Modifying without specifying it's attributes?

Question

AFAIK @Modifying is there to take care of persistence context cleanup in case of INSERT/UPDATE/DELETE queries specified in @Query annotation.
But what is pure @Modifying good for? According to this post, is seems you should always write @Modifying(clearAutomatically=true, flushAutomatically=true).

The documentation says(link):

As the EntityManager might contain outdated entities after the execution of the modifying query, we do not automatically clear it ... since this effectively drops all non-flushed changes still pending in the EntityManager

So by default @Modifying do not clean (and do not flush). Then why should I add it to my @Query method?

srikanth srikanth · Accepted Answer · 2021-01-15T15:51:10

The @Modifying annotation is used to enhance the @Query annotation to execute not only SELECT queries but also INSERT, UPDATE, DELETE, and even DDL queries.

Let's play with this annotation a little and see what it's made of.

First, let's see an example of a @Modifying UPDATE query:

@Modifying
@Query("update User u set u.active = false where u.lastLoginDate < :date")
void deactivateUsersNotLoggedInSince(@Param("date") LocalDate date);

Let's try another one where we'll delete deactivated users:

@Modifying
@Query("delete User u where u.active = false")
int deleteDeactivatedUsers();

As we can see, this method returns an integer. It's a feature of Spring Data JPA @Modifying queries that provides us with the number of updated entities.

We should note that executing a delete query with @Query works differently from Spring Data JPA's deleteBy name-derived query methods. The latter first fetches the entities from the database and then deletes them one by one. Thus, this means that the lifecycle method @PreRemove will be called on those entities. However, with the former, a single query is executed against the database.

Finally, let's add a deleted column to our USERS table with a DDL query:

@Modifying
@Query(value = "alter table USERS.USERS add column deleted int(1) not null default 0", nativeQuery = true)
void addDeletedColumn();

Unfortunately, using modifying queries leaves the underlying persistence context outdated. However, it is possible to manage this situation.

Is there any use for Spring Data JPA's @Modifying without specifying it's attributes?

3 Answers