Is there a way to use constants inside Spring Data @Query annotation value?

Question

I don't want to hardcode constant values, I would rather specify them through a reference variable.

For example, rather then writing the next query:

@Query(value = "SELECT u FROM UserModel u WHERE u.status = 1")

..I would like to extract the hardcoded value '1' and write something like:

@Query(value = "SELECT u FROM UserModel u WHERE u.status = UserModel.STATUS_ACTIVE")  //doesn't compile

Is there a way to specify constants like in the second example inside spring-data queries?

Answer 1

You have to use fully qualified class name like this:

@Query("SELECT u FROM UserModel u WHERE u.status = com.example.package.UserModel.STATUS_ACTIVE")

The bad thing about it though is that an IDE would not recognise this as an usage of the class UserModel. The only advantage is that you can keep the value in one place, which is sufficient most of the time. This has been resolved in IntelliJ IDEA 2017.1. I don't know about other IDEs.

Answer 2

I would recommend creating an Enum and a field of that enum on the entity.

public enum UserModelStatus{
     ACTIVE, INACTIVE
}

public UserModel{

    /* Other fields ommitted */

    @Enumerated(EnumType.STRING)
    private UserModelStatus status;

    /* Get/Set Method */
}

Then create your repository method:

@Repository
public interface UserModelRepository extends JpaRepository<UserModel, Long>{

    public List<UserModel> findByStatus(UserModelStatus status);

}

Using Spring Data you won't even need to write JPQL just call the method like:

   @Autowired
   UserModelRepository userModelRepository;

   public void someMethod(){
       List<UserModel> userModels = userModelRepository.findByStatus(UserModelStatus.ACTIVE);
   }

Answer 3

Use as follows:

In the repository interface, define a constant as follows:

public static final String USER_QUERY = "SELECT u FROM UserModel u WHERE u.status = " + UserModel.STATUS_ACTIVE;

Now you can use

@Query(value=USER_QUERY)