I have the following setup:
#ApplicationScope
#Component(
dependencies = {AppContextComponent.class, CertUtilsComponent.class, ServiceComponent.class, JobManagerComponent.class})
public interface ApplicationComponent
extends AppContextComponent, CertUtilsComponent, ServiceComponent, JobManagerComponent {
void inject(MainActivity mainActivity); //honestly, I won't need this
}
And I have the following subscoped component:
#PresenterScope
#Component(dependencies = {ApplicationComponent.class, PersistenceComponent.class})
public interface PresenterComponent
extends ApplicationComponent, PersistenceComponent {
void inject(HomePresenter homePresenter);
void inject(SendCertificateRequestInteractor sendCertificateRequestInteractor);
}
The problem is that PersistenceComponent has the following component as its dependency:
#Component(dependencies = {JobManagerComponent.class, RealmComponent.class, RepositoryComponent.class}, modules = {PersisterModule.class})
public interface PersisterComponent {
DummyCertPersister dummyCertPersister();
}
Which uses JobManagerComponent, which is the dependency of the ApplicationComponent.
Unfortunately, this component does not seem to be inherited from ApplicationComponent. I need to explicitly keep track of this component, and provide it for the builder like so.
//INJECTOR
ApplicationComponent applicationComponent = DaggerApplicationComponent.builder()
.appContextComponent(appContextComponent)
.certUtilsComponent(certUtilsComponent)
.jobManagerComponent(jobManagerComponent)
.serviceComponent(serviceComponent)
.build();
this.jobManagerComponent = jobManagerComponent;
this.applicationComponent = applicationComponent;
this.certUtilsComponent = certUtilsComponent;
this.appContextComponent = appContextComponent;
this.serviceComponent = serviceComponent;
}
public ApplicationComponent getApplicationComponent() {
return applicationComponent;
}
public JobManagerComponent getJobManagerComponent() {
return jobManagerComponent;
}
And provide this through a getter when I build my persistence component:
PersisterComponent persisterComponent = DaggerPersisterComponent.builder()
.jobManagerComponent(Injector.INSTANCE.getJobManagerComponent()) //this should be subcomponent
.realmComponent(realmComponent)
.repositoryComponent(repositoryComponent)
.persisterModule(new PersisterModule())
.build();
I would like to have that JobManagerComponent inherited from ApplicationComponent. I'm guessing I need to make this into a #Subcomponent and provide a provision method for it, but so far, it hasn't worked (I don't get a builder method, but it still doesn't see the jobManager within JobManagerComponent.
Is this possible with #Subcomponent? Or do I need to keep track of the "subcomponents" of ApplicationComponent in case a child component depends on it?
The answer is that I was conceptually wrong about how Components work in Dagger2.
A component should only depend on another component if it subscopes that component. A component with multiple component dependencies cannot depend on scoped components; which means they cannot have scoped modules; which also means they cannot use scopes at all and unless the module keeps a reference to the new instance, you'll get a new instance each time you inject. Which is bad, and not what you want at all.
The proper way is to bind every module of the same scope to the same component. That way, the provided dependencies are accessible within the constructors, and you won't have an issue with sharing the same module within different components as well.
Therefore, the approach in the question is completely wrong.
Use this instead.
Related
I started using dagger 2.2 and the module methods in the Component builder are deprecated.
This is my Application component :
#Component(modules = ApplicationModule.class)
public interface ApplicationComponent {
void inject(Application application);
}
And the Application module:
#Module
public class ApplicationModule {
Application application;
public ApplicationModule(Application application) {
this.application = application;
}
#Provides
#Singleton
Application providesApplication() {
return application;
}
}
Here is the generated class:
#Generated(
value = "dagger.internal.codegen.ComponentProcessor",
comments = "https://google.github.io/dagger"
)
public final class DaggerApplicationComponent implements ApplicationComponent {
private DaggerApplicationComponent(Builder builder) {
assert builder != null;
}
public static Builder builder() {
return new Builder();
}
public static ApplicationComponent create() {
return builder().build();
}
#Override
public void inject(Application application) {
MembersInjectors.<Application>noOp().injectMembers(application);
}
public static final class Builder {
private Builder() {}
public ApplicationComponent build() {
return new DaggerApplicationComponent(this);
}
/**
* #deprecated This module is declared, but an instance is not used in the component. This method is a no-op. For more, see https://google.github.io/dagger/unused-modules.
*/
#Deprecated
public Builder applicationModule(ApplicationModule applicationModule) {
Preconditions.checkNotNull(applicationModule);
return this;
}
}
}
How do I initialize the component if not with the ComponentBuilder?
You should read the description of why it is deprecated. If you are using an IDE like IntelliJ or Android Studio you can just select the method and hit Control + Q on Windows to read the Javadoc including the deprecation notice.
The Javadoc reads:
#deprecated This module is declared, but an instance is not used in the component. This method is a no-op. For more, see https://google.github.io/dagger/unused-modules.
And from this link you can see:
When the Dagger processor generates components, it only requires instances of modules and component dependencies that are explicitly needed to supply requests for a binding.
If all of a module’s methods that are used in the component are static, Dagger does not need an instance of that module at all. Dagger can invoke the static methods directly without a module.
If a module provides no bindings for a Component, no instance of that module is necessary to construct the graph.
It is safe to say that you can just ignore the deprecation. It is intended to notify you of unused methods and modules. As soon as you actually require / use Application somewhere in your subgraph the module is going to be needed, and the deprecation warning will go away.
It show deprecated because you are not using Component and module in your application by
#Inject
SomeObjectFromModule mSomeObject
if you are not injecting dependencies in your applications there is no use of initialising your component so dagger look for at least one usage
once you add these lines in any classes you want to inject views and then clean build and rebuild the project and your deprecation will be solved
It showing error when my Module have no #Provides method or the object that provide by Dagger is not used in app.
Example to remove deprecated module
Module
#Module
public class SecondActivityModule {
#Provides
Book provideBookTest() {
return new Book();
}
}
Activity
public class SecondActivity extends AppCompatActivity {
#Inject
Book test;
...
}
OR in Component
#Component(modules = SecondModule.class)
public interface SecondComponent {
void inject(SecondActivity activity);
Book getBookTest();
}
I have the same problem with host and I just want everyone has deprecated issue on Generated component builder class should check two things to save time:
1/ Correct dagger syntax for module, component also check carefully where you inject.
2/ Must have injection object (inject annotation and its object) in place you want to inject or else the dagger compiler cannot see where to use your module so some method will be deprecated.Just inject at least one module's provides to your injection place and re-compile the code, you won't have that issue anymore :)
you will get module method deprecated if you declare void inject(AppCompactActivity activity); in component class. instead of you have to use tight coupling like following void inject(MainActivity activity);and rebuild your project you will see, there is no deprecate method in module class
I have this component:
#Singleton
#Component(modules = OauthModule.class)
public interface OauthComponent {
void inject(LoginActivity a);
}
and the module:
#Module
public class OauthModule {
#Provides
#Singleton
Oauth2Service provideOauth2Service() {
return new Oauth2StaticService();
}
}
and this another component:
#Singleton
#Component(modules = LoggedUserModule.class)
public interface LoggedUserComponent {
void inject(LoginActivity a);
}
and I get this error:
Error:(15, 10) error: Oauth2Service cannot be provided without an
#Provides- or #Produces-annotated method.
If I change the LoggedUserComponent's inject method parameter to be another Activity, say AnotherActivity like this:
#Singleton
#Component(modules = LoggedUserModule.class)
public interface LoggedUserComponent {
void inject(AnotherActivity a);
}
compilation is ok. Why? Can't I have two components with the same inject signature?
I'm trying to understand how Dagger works so any help will be appreciated. Thanks.
Think of dagger as an object graph—which it actually is. You probably should not have 2 different components being able to inject the same object, other than for testing purposes (or if you want to include different behavior, not additional one).
If your LoginActivity depends on multiple modules, you should aggregate them in a single component, since as your error shows, dagger will fail if it can not provide all dependencies from a single component.
#Singleton
#Component(modules = {LoggedUserModule.class, OauthModule.class})
public interface LoggedUserComponent {
void inject(AnotherActivity a);
}
Looking at Oauth2Service, this could easily be something that multiple objects could use, so a higher scope could be adequate. In that case you should think about adding it with a #Singleton scope to your application component, or maybe create its own component with e.g. a #UserScope.
Then you would have to either make your LoggedUserComponent a #Subcomponent or declare this component a dependency using #Component(dependencies = OauthComponent.class) and providing a getter in OauthComponent for it. In both cases dagger would also be able to provide the dependency found higher in the graph, thus also resolving your error.
It's getting mad because you're saying you can inject into that class but you're not providing a class that it's expecting you to provide. You just need to add the OauthModule to your LoggedUserComponent. Try this
#Singleton
#Component(modules = {LoggedUserModule.class, OauthModule.class})
public interface LoggedUserComponent {
void inject(LoginActivity loginActivity);
}
I've created a component and it only last for the lifetime of the activity. I did not use any scope annotations and only quick example of the life time of the component looks like this:
public class MainActivity extends AppCompatActivity {
private final String TAG = getClass().getSimpleName();
#Inject
AlmondButter someAlmondButter;
#Inject
CashewSandwich sandwich;
SandwichComponent sandwichComponent;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/*create thte dependent butter for the sandwich here*/
ButterComponent butterComponent=DaggerButterComponent.builder().
butterModule(new ButterModule()).build();
/*create a scope sandwichcomponent here */
sandwichComponent=DaggerSandwichComponent.builder().sandwichModule(new SandwichModule()).
butterComponent(butterComponent)
.build();
//finally we have a sandwichComponent, lets inject our dependencies
sandwichComponent.inject(this);
Log.v(TAG,sandwich.toString());
Log.v(TAG,someAlmondButter.toString());
}
#Override
protected void onDestroy() {
super.onDestroy();
//not necessary but it clearly shows the scope being tied to lifecycle of activity
sandwichComponent=null;
}
}
none of my components are scoped with anotations and it works fine. So im confused why some recommend to create scope tags, what is there purpose ? i'll show you my components below for reference:
#Component(dependencies = ButterComponent.class, modules = SandwichModule.class)
public interface SandwichComponent {
CashewSandwich ProvideCashewSandwitch();
void inject (MainActivity mainactivity);
}
and the next component:
#Component(modules={ButterModule.class})
public interface ButterComponent {
//these are for our whatever class depends on butter
AlmondButter ProvideAlmondButter();
CashewButter ProvideCashewButter();
}
UPDATE: FOR ANYONE WHO NEEDS HELP WITH UNDERSTANDING THESE CONCEPTS I MADE A BLOG HERE.
By using scopes on component and scopes on module provider method, you can ask Dagger2 to create scoped providers for you.
In order to get a scoped provider in your module's provider method, you must put the scope on the component as well.
You can specify only one scope on a given component, and in a scoped component, you can only have modules with that scope on its provider methods, or the provider methods can also be unscoped.
Unscoped providers give you a new instance on every inject call.
Scoped providers store a single instance for every inject call to that specific component instance.
#Component(modules={HelloModule.class})
#Singleton
public interface HelloComponent {
Hello hello();
World world();
void inject(MainActivity mainActivity);
}
#Module
public class HelloModule {
#Provides
public Hello hello() { return new Hello(); } //new instance each call to inject
#Provides
#Singleton
public World world() { return new World(); } //one instance per component
}
It is also worth noting that if you subscope another component to inherit its dependencies (using subcomponent or component dependency), you can only depend on one other scoped component. Think of it like how "multiple inheritance" is not allowed in Java, you also cannot depend on multiple scoped components and inherit their dependencies, only one.
Typically you have a singleton scope, and you subscope your components according to the top-level separation of modules in your application.
#Component(modules={ApplicationModule.class})
#Singleton
public interface ApplicationComponent {
Something something();
}
#Component(dependencies={ApplicationComponent.class}, modules={MainActivityModule.class})
#ActivityScope
//this is a subscoped component that inherits from ApplicationComponent
public interface MainActivityComponent extends ApplicationComponent {
OtherThing otherThing();
void inject(MainActivity mainActivity);
}
According to Martin Fowler, the right way to slice your application into pieces on the top-level is by features, such as GalleryComponent, SettingsComponent, etc. and not by layers (data, domain, presentation).
Scopes manage the instance creation across multiple requests for the same type. Imagine if you had this:
#Inject
AlmondButter someAlmondButter;
#Inject
AlmondButter otherAlmondButter;
This would create two separate AlmondButter instances. A trivial case, but hopefully it illustrates the point that each time you request the dependency, a new one is created.
Imagine now you have two different classes, each with a field #Inject AlmondButter sharedAlmondButter. If you want them to have the same exact instance, a scope will handle that for you.
Similarly, with any dependency you have, you can inject a Provider<T>, i.e. #Inject Provider<AlmondButter> almondButterProvider. This can allow you to call almondButterProvider.get() to retrieve a new instance. If you then wanted all values returned by .get() to be the same instance, a scope would accomplish the same thing.
Yes, I know this has been asked before, and yes, I know it is "by design".
But I'd like to do something like this:
#Component(modules = {RealmModule.class})
public interface RealmComponent {
Realm realm();
}
#Component(modules = {RepositoryModule.class})
public interface RepositoryComponent {
PersonRepository personRepository();
ScheduleRepository schedulesRepository();
}
#Component(dependencies = {RealmComponent.class, RepositoryComponent.class})
public interface AppDataComponent
extends RealmComponent, RepositoryComponent {
}
#ApplicationScope
#Component(dependencies = {AppContextComponent.class,
AppDataComponent.class,
AppDomainComponent.class,
AppPresentationComponent.class,
AppUtilsComponent.class})
public interface ApplicationComponent
extends AppContextComponent, AppDataComponent, AppDomainComponent, AppUtilsComponent, AppPresentationComponent {
void inject(CustomApplication customApplication);
void inject(DashboardActivity dashboardActivity);
}
However, what I get is unscoped, every time I inject a JobManager or a ScheduleRepository or anything else, I get a new instance. The only way I could "fix" that was this.
#Module
public class JobManagerModule {
private JobManager jobManager;
#Provides
public JobManager jobManager(Context context) {
if(jobManager == null) {
jobManager = new JobManager(context, new Configuration.Builder(context).networkUtil(
new WifiOrMobileNetworkUtil(context)).build());
}
return jobManager;
}
}
Not a fan.
So, how is one meant to structure and rip apart the dependency tree, without making one big gigantic über blob component that has every single module listed and every single provision method (instead of these "subcomponent" component dependencies)?
I tried using subcomponents for this, but then you have to provide every single module for the final ApplicationComponent.
I'm not sure what to do here. I tried specifying #Singleton for every first-level component and #SubcomponentScope for every AppDataLevelComponent, I also tried making a new scope for every single subcomponent, but both of them failed with "cannot depend on multiple scoped components".
EDIT: Apparently in order to get scoped providers, marking the components with the scope is not enough - you must specify the scope for the #Provides annotated methods too.
#Module
public class RepositoryModule {
#Provides
#Singleton
public PersonRepository personRepository() {
return new PersonRepositoryImpl();
}
#Provides
#Singleton
public ScheduleRepository schedulesRepository() {
return new SchedulesRepositoryImpl();
}
}
In the meantime, I ended up with this übercomponent.
#Singleton
#Component(modules = {
AppContextModule.class,
DbMapperModule.class,
DbTaskModule.class,
RealmModule.class,
RepositoryModule.class,
InteractorModule.class,
ServiceModule.class,
PresenterModule.class,
XmlPersisterModule.class
})
public interface ApplicationComponent
extends AppContextComponent, AppDataComponent, AppDomainComponent, AppUtilsComponent, AppPresentationComponent {
Where the xyzComponent classes are just interfaces to store the provision methods...
(Please note that this structure is an anti-pattern as described by Martin Fowler, and you should organize modules based on features / activities, and make them into subscoped components using component dependencies. Component dependencies are used to subscope your superscope components, and "inherit" dependency providers.)
I had same problems like you not while ago and ended using the same ubercomponent approach except I use #Subcomponents in order organize the things and not to have all modules listed in the ubercomponent (I call it "top" or "app's" component).
You may see an example here:
How to migrate missing inject from module with complete = false from Dagger 1 to Dagger 2
I'm a beginner with dependency injection.. specifically Dagger 2. I'm trying to figure out if/how I can do something like this:
#Inject
public void someMethodName(int someInteger, SomeObject dependency){
// do something with the dependency.
}
Or do I need to put that dependency in as a class var? any help with this would be greatly appreciated. also in this case the variable someInteger is not a dependency, but is being added by the caller... does that matter?
can I call it like this:
this.someMethodName(5);
android studio does not like the above calling method (I'm assuming because I'm doing something wrong)
You need to create component which is annotated by #Component.
The Component accepts module which provides dependencies.
Every component's name that you create starts with Dagger prefix, e.g. for MyComponent.
Let's look at the following example:
#Singleton
#Component(modules = DemoApplicationModule.class)
public interface ApplicationComponent {
void inject(DemoApplication application);
}
We created ApplicationComponent with single injection method. What we're saying is that we want to inject certain dependencies in DemoApplication.
Moreover, in the #Component annotations we specify module with provision methods.
This is like our module looks like:
#Module
public class DemoApplicationModule {
private final Application application;
public DemoApplicationModule(Application application) {
this.application = application;
}
#Provides #Singleton SomeIntegerHandler provideIntegerHandler() {
return new MySomeIntegerHandlerImpl();
}
}
What we're saying by creating DemoApplicationModule is that the module can provide desired dependencies in the injection place specified by our Component.
public class DemoApplication extends Application {
private ApplicationComponent applicationComponent;
#Inject SomeIntegerHandler handler;
#Override public void onCreate() {
super.onCreate();
applicationComponent = DaggerApplicationComponent.builder()
.demoApplicationModule(new DemoApplicationModule(this))
.build();
applicationComponent.inject(this);
handler.someMethodName(5);
}
}
See documentation what you kind of dependencies you can obtain. Additionally to obtaining just raw instance you can obtain Provider, Factory or Lazy instance.
http://google.github.io/dagger/api/latest/dagger/Component.html
You can also create scoped dependencis, the lifecycles of which depend on the lifecycle of injection places, like Activities or Fragments.
Hope I gave you the basic notion of what Dagger is.
YOU CAN USE SOME INTERFACE
public interface myDependence{
int myFunction(int value);
}
NOW IMPLEMENT IN YOU CLASS
public myClass implements MyDependence{
#Override
int myFunction(int value){
// do something
}
}