I've been playing around with the MVP pattern for a few weeks now and I've come to the point where I need context to start a service and access Shared Preferences.
I've read that the purpose of MVP is to decouple the view from the logic and having context within a Presenter may defeat that purpose (correct me if I'm wrong on this).
Currently, I have a LoginActivity that looks something like this:
LoginActivity.java
public class LoginActivity extends Activity implements ILoginView {
private final String LOG_TAG = "LOGIN_ACTIVITY";
@Inject
ILoginPresenter mPresenter;
@Bind(R.id.edit_login_password)
EditText editLoginPassword;
@Bind(R.id.edit_login_username)
EditText editLoginUsername;
@Bind(R.id.progress)
ProgressBar mProgressBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
MyApplication.getObjectGraphPresenters().inject(this);
mPresenter.setLoginView(this, getApplicationContext());
}
@Override
public void onStart() {
mPresenter.onStart();
ButterKnife.bind(this);
super.onStart();
}
@Override
public void onResume() {
mPresenter.onResume();
super.onResume();
}
@Override
public void onPause() {
mPresenter.onPause();
super.onPause();
}
@Override
public void onStop() {
mPresenter.onStop();
super.onStop();
}
@Override
public void onDestroy() {
ButterKnife.unbind(this);
super.onDestroy();
}
@OnClick(R.id.button_login)
public void onClickLogin(View view) {
mPresenter.validateCredentials(editLoginUsername.getText().toString(),
editLoginPassword.getText().toString());
}
@Override public void showProgress() { mProgressBar.setVisibility(View.VISIBLE); }
@Override public void hideProgress() {
mProgressBar.setVisibility(View.GONE);
}
@Override public void setUsernameError() { editLoginUsername.setError("Username Error"); }
@Override public void setPasswordError() { editLoginPassword.setError("Password Error"); }
@Override public void navigateToHome() {
startActivity(new Intent(this, HomeActivity.class));
finish();
}
}
Presenter Interface ILoginPresenter.java
public interface ILoginPresenter {
public void validateCredentials(String username, String password);
public void onUsernameError();
public void onPasswordError();
public void onSuccess(LoginEvent event);
public void setLoginView(ILoginView loginView, Context context);
public void onResume();
public void onPause();
public void onStart();
public void onStop();
}
Lastly, my Presenter:
LoginPresenterImpl.java
public class LoginPresenterImpl implements ILoginPresenter {
@Inject
Bus bus;
private final String LOG_TAG = "LOGIN_PRESENTER";
private ILoginView loginView;
private Context context;
private LoginInteractorImpl loginInteractor;
public LoginPresenterImpl() {
MyApplication.getObjectGraph().inject(this);
this.loginInteractor = new LoginInteractorImpl();
}
/**
* This method is set by the activity so that way we have context of the interface
* for the activity while being able to inject this presenter into the activity.
*
* @param loginView
*/
@Override
public void setLoginView(ILoginView loginView, Context context) {
this.loginView = loginView;
this.context = context;
if(SessionUtil.isLoggedIn(this.context)) {
Log.i(LOG_TAG, "User logged in already");
this.loginView.navigateToHome();
}
}
@Override
public void validateCredentials(String username, String password) {
loginView.showProgress();
loginInteractor.login(username, password, this);
}
@Override
public void onUsernameError() {
loginView.setUsernameError();
loginView.hideProgress();
}
@Override
public void onPasswordError() {
loginView.setPasswordError();
loginView.hideProgress();
}
@Subscribe
@Override
public void onSuccess(LoginEvent event) {
if (event.getIsSuccess()) {
SharedPreferences.Editor editor =
context.getSharedPreferences(SharedPrefs.LOGIN_PREFERENCES
.isLoggedIn, 0).edit();
editor.putString("logged_in", "true");
editor.commit();
loginView.navigateToHome();
loginView.hideProgress();
}
}
@Override
public void onStart() {
bus.register(this);
}
@Override
public void onStop() {
bus.unregister(this);
}
@Override
public void onPause() {
}
@Override
public void onResume() {
}
}
As you can see, I passed the context from the Activity into my Presenter just so I can access the Shared Preferences. I'm quite worried about passing the context into my presenter. Is this an okay thing to do? Or should I be doing it some other way?
EDIT Implemented Jahnold's 3rd preference
So let's ignore the interface and implementation because it's pretty much the entire thing. So now I'm injecting the interface for the Sharedpreference into my presenter. Here's my code for the AppModule
AppModule.java
@Module(library = true,
injects = {
LoginInteractorImpl.class,
LoginPresenterImpl.class,
HomeInteractorImpl.class,
HomePresenterImpl.class,
}
)
public class AppModule {
private MyApplication application;
public AppModule(MyApplication application) {
this.application = application;
}
@Provides
@Singleton
public RestClient getRestClient() {
return new RestClient();
}
@Provides
@Singleton
public Bus getBus() {
return new Bus(ThreadEnforcer.ANY);
}
@Provides
@Singleton
public ISharedPreferencesRepository getSharedPreferenceRepository() { return new SharedPreferencesRepositoryImpl(application.getBaseContext()); }
}
}
The way I get the context is from MyApplication.java
When the application begins, I make sure to create this Object graph with this line of code:
objectGraph = ObjectGraph.create(new AppModule(this));
Is this okay? I mean I now don't have to pass the context from the activity into my presenter, but I still have context of the application.