How does Hilt inject ViewModel parameters

Question

In the documentation on Hilt, it shows this example of injecting a viewmodel into an activity:

@HiltViewModel
class ExampleViewModel @Inject constructor(
  private val savedStateHandle: SavedStateHandle,
  private val repository: ExampleRepository
) : ViewModel() {
  ...
}

@AndroidEntryPoint
class ExampleActivity : AppCompatActivity() {
  private val exampleViewModel: ExampleViewModel by viewModels()
  ...
}

But what if ExampleRepository itself has a constructor that requires parameters? How would the code in the activity be different? How do you tell Hilt what parameters to pass to Repository?

Answer 1

there is multiple ways but I'll mention one I use for parameters that are from custom type like retrofit api service or OKHttp you need to provide it like below

@Module
@InstallIn(SingletonComponent::class)
object NetworkModule {
    @Provides
    fun provideOkHttpClient(
        @ApplicationContext context: Context,
        networkManager: NetworkManager,
        authenticator: AuthInterceptor,
        preferenceHelper: PreferenceHelper
    ): OkHttpClient {
        val httpLogging = HttpLoggingInterceptor()
        httpLogging.level = HttpLoggingInterceptor.Level.BODY
        val httpClient = OkHttpClient.Builder()
            .addInterceptor(authenticator)
            .connectTimeout(5, TimeUnit.MINUTES)
            .callTimeout(5, TimeUnit.MINUTES)
            .readTimeout(2, TimeUnit.MINUTES)
            .writeTimeout(2, TimeUnit.MINUTES)
        if (BuildConfig.BUILD_TYPE == Constants.STAGING_RELEASE)
            httpClient.addInterceptor(httpLogging)
        httpClient.addInterceptor(ChuckInterceptor(context))
        val httpCacheDirectory = File(context.cacheDir, "responses")
        val cacheSize: Long = 10 * 1024 * 1024
        val cache = Cache(httpCacheDirectory, cacheSize)
        httpClient.cache(cache)
        return httpClient.build()
    }
}
in this way when a parameter of type OkHttpClient is needed, this function will return it