Null reference on Dagger 2 #Inject - firebase

Question

I've created a gist highlighting the issue I'm running into. I'm using an Application Module to provide a Firebase dependency for me to inject elsewhere.
When I try to #Inject Firebase mFirebase in the data layer that dependency is never satisfied.
I'm trying to keep the Context out of my other layers, but the Firebase service depends on it. I'm interested in learning any other patterns to help keep Android classes out of my business logic.
FirebaseService.java
public class FirebaseService {
#Inject Firebase mFirebaseRef; //NEVER GET'S INJECTED!
#Override
public LoginResult signinWithEmail(final String email, final String password) {
mFirebaseRef.dostuff(); //THIS REFERENCE DOESN'T GET INJECTED!
}
}
ApplicationModule
#Provides
#Singleton
Firebase provideFirebase(#ApplicationContext Context context) {
Firebase.setAndroidContext(context);
return new Firebase(Util.FIREBASE_URL);
}
ApplicationComponent
#Singleton
#Component(modules = ApplicationModule.class)
public interface ApplicationComponent {
#ApplicationContext Context context();
Application application();
Firebase firebase();
}
MyActivity
public class MyActivity extends AppCompatActivity {
private ActivityComponent mActivityComponent;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public ActivityComponent getActivityComponent() {
if (mActivityComponent == null) {
mActivityComponent = DaggerActivityComponent.builder()
.activityModule(new ActivityModule(this))
.applicationComponent(MyApplication.get(this).getComponent())
.build();
}
return mActivityComponent;
}
The full code example is on github

Answer 1

Annotating a field with #Inject is not enough for the field injection to work. There's no magic involved, you just have to tell Dagger to do the injection.
First, add this method to your ApplicationComponent:
void inject(FirebaseService firebaseService);
Then, call this method from your FirebaseService (I guess it's an Android service, so add this to the onCreate method):
applicationComponent.inject(this);
This should do the trick. There's a great answer to a similar problem here.
EDIT
I've looked at your repository and I think you don't even need field injection in this case. You can just provide the Firebase dependency through a constructor. Here's your #Provides method:
#Provides
#Singleton
LoginService provideLoginService() {
return new FirebaseLoginService();
}
Add Firebase as a parameter to it and pass it to the FirebaseLoginService constructor:
#Provides
#Singleton
LoginService provideLoginService(Firebase firebase) {
return new FirebaseLoginService(firebase);
}
The constructor:
public FirebaseLoginService(Firebase firebase) {
this.mFirebaseRef = firebase;
}
Remove the #Inject annotation from your mFirebaseRef field since it's not needed anymore.
Here's the corresponding pull request.