Dagger: Inject named string in constructor

9
votes

I have a properties file and I would like to inject a property in a service.

I would like use the constructor method for DI like this:

@Inject
public ScanService(@Named("stocks.codes") String codes, IYahooService yahooService) {
    this.yahooService = yahooService;
    this.codes = codes;
}

I try to do a module like specified in this link => Dagger: Inject @Named strings?

@Provides
@Named("stocks.code")
public String providesStocksCode() {
    return "test";
}

And for the provider method for my service:

@Provides
@Singleton
public IScanService provideScanService(String codes, IYahooService yahooService){
    return new ScanService(codes, yahooService);
}

When I run the compilation I get this error:

[ERROR] /Users/stocks/src/main/java/net/modules/TestModule.java:[22,7] error: No injectable members on java.lang.String. Do you want to add an injectable constructor? required by provideScanService(java.lang.String,net.IYahooService) for net.modules.TestModule

How can I inject my property correctly in the constructor ?

Thanks.

2
propertiesdependency-injectiondagger

2 Answers

10
votes

If you mean Dagger 2, I can help you. First you have to declare dependencies in Component

@Singleton
@Component(modules = ApplicationModule.class)
public interface ApplicationComponent {
    void inject(BaseActivity baseActivity);

    @Named("cloud") UserDataSource userCloudSource();
    @Named("disc") UserDataSource userDiscSource(); 
    UserDataRepository userDataRepository();  
}

then instantiate it in Module 

@Module
public class ApplicationModule {

    @Provides @Named("cloud")
    UserDataSource provideCloudUserSource(UserCloudSource userSource) {
        return userSource;
    }

    @Provides @Named("disc")
    UserDataSource provideDiscUserSource(UserDiscSource userSource) {
        return userSource;
    }

    @Provides
    UserDataRepository provideUserRepository(UserDataRepository repository) {
        return repository;
    }

}

then inject it in constructor with @Named qualifiers

@Inject
public UserDataRepository(@Named("cloud") UserDataSource cloudSource, 
     @Named("disc") UserDataSource discSource) {
    this.cloudDataSource= cloudSource;
    this.discDataSource = discSource;
}
9
votes

You have two different names: stocks.codes and stocks.code.

You will also have to annotate your provideScanService codes parameter:

@Provides
@Singleton
public IScanService provideScanService(@Named("stocks.codes") String codes, IYahooService yahooService){
    return new ScanService(codes, yahooService);
}

Or do it like this:

@Provides
@Singleton
public IScanService provideScanService(ScanService scanService){
    return scanService;
}