Refit + Prism Forms + Fusillade

IApiService.cs

public interface IApiService<TInterfaceService>
{
    // Use to fetch data into a cache when a page loads. Expect that
    // these requests will only get so far then give up and start failing
    TInterfaceService Speculative { get; }

    // Use for network requests that are fetching data that the user is
    // waiting on *right now*
    TInterfaceService UserInitiated { get; }

    // Use for network requests that are running in the background
    TInterfaceService Background { get; }
}

Step 1 : - https://gist.github.com/hamid-shaikh/24d93419f9b5313685c4dfc40f4b59dc
Step 2 : - https://gist.github.com/hamid-shaikh/7a766529e79cea8e108d53c657ca1594
Step 3 : - https://gist.github.com/hamid-shaikh/803e88151281e24bc07fba2a4903cc49
Step 4 : - https://gist.github.com/hamid-shaikh/082fea0c0bb3accc7c1db180d81a9884
Step 5 : - https://gist.github.com/hamid-shaikh/0774fe04cf7121c0d596925c93fc1809

assalamualaikum. hi.

TInterfaceService <- can u explain this ?

@syahman
Walaikum Assalam

Please go through all the steps to get more details.

TInterfaceService - Will be your "service interface", which you have define while doing registration. Please check Step 4
The idea is to get appropriate "Service object" at runtime using IOC. For example if you have below two services.

1. IAuthenticationService
2. ISomeDataService

So, Registering to IOC container will be like below.

protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
    containerRegistry.RegisterSingleton<IApiService<IAuthenticationService>, ApiService<IAuthenticationService>>();
    containerRegistry.RegisterSingleton<IApiService<IAuthenticationService>, ApiService<ISomeDataService>>();
    containerRegistry.RegisterForNavigation<NavigationPage>();
    containerRegistry.RegisterForNavigation<LoginPage, LoginPageViewModel>();
}

Inject required service at ViewModel constructor.

public partial class LoginPageViewModel
{
    public LoginPageViewModel(INavigationService navigationService, 
                              IApiService<IAuthenticationService> authenticationService)
    {
        NavigationService = authenticationService;
        AuthenticationService = authenticationService;//Here you will get AuthenticationService object injected
    }
}

or

public partial class HomePageViewModel
{
    public HomePageViewModel(INavigationService navigationService, 
                              IApiService<ISomeDataService> someDataService)
    {
        NavigationService = authenticationService;
        SomeDataServiceService = someDataService;//Here you will get SomeDataService object injected
    }
}

Also, There are high possibility that your application integrate more than one "Service" providers and this can help you easily identify service provider type.

For example:- Let's say your application is consuming two "Service Provider" for Authentication.
so you can create two Interface like below.

IServiceProvider1
IServiceProvider2

Now, at runtime while creating HttpClient object inside ApiService.cs file you can simply check Interface type and return appropriate HttpClient object.

TInterfaceService CreateHttpClient()
 {
       bool isServiceProvider1 = typeof(TInterfaceService).GetInterface(nameof(IServiceProvider1)) != null;
       HttpClient client;
       if(isServiceProvider1)
      {
           client = new HttpClient(messageHandler)
           {
                 BaseAddress = new Uri(AppConstants.BaseAddressServiceProvider1),
                 Timeout = TimeSpan.FromSeconds(AppConstants.Timeout)
            };
       }
      else
      {
            client = new HttpClient(messageHandler)
           {
                  BaseAddress = new Uri(AppConstants.BaseAddressServiceProvider2),
                  Timeout = TimeSpan.FromSeconds(AppConstants.Timeout)
            };
        }

        client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
        //client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");
        return RestService.For<TInterfaceService>(client, new RefitSettings
        {
            ContentSerializer = new JsonContentSerializer(jsonSerializerSettings)
        });
} 

Please let me know if u still have any query.

dear hamid-shaikh, very thankful for your explanation, now i understand how D.I works in Prism. Being searching this method for almost a week.

i would like to add another nuget to my project instead of Refit + Prism Forms + Fusillade, there will be fody.propertychanged,aritchie Acr.UserDialogs,Polly and Plugin.connectivity. hope this will integrate well with prism. maybe need workaround if i need to inject static interface. so far my prism project able to get API data. what's the difference between RegisterSingleton and RegisterInstance ?

/* Services, D.I */
            containerRegistry.RegisterSingleton<IApiService<IAuthenticationService>, ApiService<IAuthenticationService>>();
            containerRegistry.RegisterInstance(typeof(IUserDialogs), UserDialogs.Instance);

@syahman
To understand difference better kindly visit Prism documentation (Very good documentation)

Prism Forms Documentation

One suggestion - Use Xamarin.Essential for Connectivity instead of Plugin.Connectivity