CODEWITHSUNDEEP
javahibernaterestdependency-injectionquarkus
Mitsch
Mitsch

Reputation: 3

Injected Bean not instantiated when used in member variable

My injected EntityManager is not initiated when used in a member variable. When I use it inside a method, it is initiated.

Is this a problem that has to do with the instantiation time of injected beans in general? Or is it only because I'm using quarkus and hibernate?

    @Inject
    EntityManager entityManager;

    private StudentFacade studentFacade = new StudentFacade(entityManager); //entityManager is null

The variable "entityManager" should be initiated, but it has a null value.

Upvotes: 0

Views: 1760

Answers (2)

geoand
geoand

Reputation: 64079

Quarkus also supports constructor injection, so you could also do something like:

@Singleton
public class MyBean {

   final StudentFacade studentFacade;

   public MyBean(EntityManager entityManager) {
      this.studentFacade = new StudentFacade(entityManager);
   }

}

Upvotes: 2

Dmytro Grynets
Dmytro Grynets

Reputation: 953

The problem is that studentFacade is initialized upon constructing whatever object holds the entityManage, but whatever framework you use for DI - injects entityManager only after object constructing.

So upon initializing of studentFacade field - entityManager is still null.

To solve this problem you can delay initializing of studentFacade variable until after injects. Usually it is accomplished by using some life-cycle hooks, like:

@PostConstruct
public void onConstruct() {
    studentFacade = new StudentFacade(entityManager);
}

Example is given for Spring framework but I guess almost the same rules applied to whatever you use.

Upvotes: 1

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