Blazor - HttpClient Depencency Injection for HttpProxy

[rfcdejong]

I need to add a header on each request from Blazor to the server, but currently it feels wrong to me.

Current solution in Program.cs Main:

builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

And the HttpClient is injected into the Csla HttpProxy. I think the current solution is to implement a custom HttpProxy and override GetHttpClient and do stuff there.

However I think it would be better to allow HttpClientFactory or Typed HttpClient and use AddHttpClient and explicitly define it for a new class DataportalHttpClient which should be used in HttpProxy.

builder.Services.AddHttpClient<DataportalHttpClient>(client => client.BaseAddress = new Uri(builder.HostEnvironment.BaseAddress))
      .AddHttpMessageHandler<BaseAddressAuthorizationMessageHandler>();

This gives more flexibility, in this case I add BaseAddressAuthorizationMessageHandler, this ensures that an accesstoken is passed along to the server which will be validated beside trusting the deserialized claimsprincipal which could be manually modified.

[rfcdejong]

I did implement a tiny bit nicer solution, which works and passes along the jwt token in the authorization header.

    public class DataportalHttpProxy : HttpProxy
    {
        private readonly HttpClient _httpClient;

        public DataportalHttpProxy(IHttpClientFactory clientFactory)
        {
            _httpClient = clientFactory.CreateClient("ServerAPI");
        }

        protected override HttpClient GetHttpClient()
        {
            return _httpClient;
        }
    }

and in Program.cs

     //            builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

     builder.Services.AddHttpClient();
     builder.Services.AddHttpClient("ServerAPI", client => client.BaseAddress = new Uri(builder.HostEnvironment.BaseAddress))
         .AddHttpMessageHandler<BaseAddressAuthorizationMessageHandler>();

     builder.UseCsla(c => c.DataPortal().DefaultProxy(typeof(DataportalHttpProxy), "/api/DataPortal"));

[rockfordlhotka]

I can't argue with the use of IHttpClientFactory, other than that the Blazor project templates all set up HttpClient for use.

I want to support the "easy F5 path", which means supporting HttpClient. I think that's important.

At the same time, I think you are right. It is important to support the superior IHttpClientFactory model.

Maybe the answer is to do what you've done, and include two "HttpProxy" types, one for each scenario?

[mtavares628]

Is there any other code that's missing to make that work? I've created the same DataportalHttpProxy class, and I was under the impression that the AddHttpClient() calls would be enough to inject the IHttpClientFactory into the constructor of the derived proxy class, but when I run it I'm getting an error saying: Cannot create instance of Type 'DataportalHttpProxy'. No public parameterless constructor found. Do I need to register the DataportalHttpProxy class as well? Here's what my Program.cs looks like:

public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);
            builder.RootComponents.Add<App>("#app");

            //builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

            builder.Services.AddHttpClient();
            builder.Services.AddHttpClient("DadApi", client => client.BaseAddress = new Uri(builder.HostEnvironment.BaseAddress))
                .AddHttpMessageHandler<BaseAddressAuthorizationMessageHandler>();

            builder.Services.AddOidcAuthentication(options =>
            {
                builder.Configuration.Bind("oidc", options.ProviderOptions);
            });
            App.IsServerSide = false;

           builder.Services.AddAuthorizationCore();
           builder.Services.AddOptions();
           builder.Services.AddSingleton<CslaUserService>();

            builder.UseCsla(c => c
                .DataPortal()
                .DefaultProxy(typeof(DataportalHttpProxy),
                              "https://localhost:6001/api/dataportaltext/")
                );
            
            await builder.Build().RunAsync();
        }

Any insight would be greatly appreciated.