CODEWITHSUNDEEP
springjpaspring-data-jpa
JuNe
JuNe

Reputation: 1997

How to use @Autowired in an class annotated with @Entity?

I have an entity called TimeBooking. When I request this entity and return to the client I want to get a list of ActivityTimeBookings from a repository. But when the function get called the repo is null. So I tried to @Autowired the repo and marked it as transient and also said Spring that there is a dependency which should be injected.

@Configurable(preConstruction = true)
@Entity
public class TimeBooking extends BaseEntity{

    @Autowired
    private transient ActivityTimeBookingRepository activityTimeBookingRepository;

    ...

    @JsonProperty("activityTimeBookings")
    private List<ActivityTimeBooking> activityTimeBookings() {
        return this.activityTimeBookingRepository.findByDate(this.timeFrom);
    }
}

Any suggestions?

Upvotes: 2

Views: 833

Answers (2)

Anish B.
Anish B.

Reputation: 16469

Using @Autowired in a class annotated with @Entity is a bad practice.

The solution is given below :

1. Create a service interface :

public interface TimeBookingService {

   public List<ActivityTimeBooking> activityTimeBookings();

}

2. Create an implementation of the service interface :

@Service
public class TimeBookingServiceImpl implements TimeBookingService {

    @Autowired
    private ActivityTimeBookingRepository activityTimeBookingRepository;

    public List<ActivityTimeBooking> activityTimeBookings() {
        return this.activityTimeBookingRepository.findByDate(this.timeFrom);
    }
}

Upvotes: 2

Mark Bramnik
Mark Bramnik

Reputation: 42461

Usually its indeed a bad practice to inject something into JPA entities. These are usually created by JPA implementation (like Hibernate) and spring as a DI framework doesn't really participate in this process.

Note, that there can be many instances of this class created as a result of query, so if you later use this for serialization of the list of this object you might end up running N queries to the database given N entities like this were retrieved.

Answering your question about "getting access to the repo" I believe you should consider refactoring:

In the service class (assuming you have a "regular" contoller, service and dao):

you can:

class MyService {
    SomeResult.. doSomething() {
     List<TimeBooking> allTimeBookings = dao.getAllTimeBooking();
     LocalDateTime timeFrom = calculateTimeFrom(allTimeBookings);
     List<ActivityTimeBooking> allActivityTimeBookings = dao.findByDate(timeFrom);
     return calculateResults(allTimeBookings, allActivityTimeBooking);        
    }
}

class MyDao {
  List<ActivityTimeBooking> findByDate(LocalDateTime timeFrom) {...}

  List<TimeBooking> getAllTimeBookings() {...}
}

Regarding the service implementation, I've assumed this use case can't be covered by usual "JOIN between two tables" so that that creating an association between TimeBooking and ActivityTimeBooking is not an option.

Note 2, I've used one repository (dao) for brevity, in real application you might want to inject two different repositories into the service.

Upvotes: 2

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