Unable to resolve HttpClient when using AddHttpClient in a .Net Generic Host that is not HTTP Server Implementation

Question

I have built a command-line app using .net core 3.0 using the Generic Host Builder. If I add a HttpClient to the services using AddHttpClient the the service requesting HttpClient fails to resolve with an error "Unable to resolve service for type 'System.Net.Http.HttpClient'"

If I register HttpClient myself then it resolves, so it appears that the AddHttpClient does not work unless it is a Http Server.

I find the whole AddHttpClient approach a bit more attractive as I can easily add policies etc. In fact I am trying to create a reusable component that I can share between applications(web and non-web) which builds a consistent HttpClient.

Building Host

        public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureServices((hostContext, services) =>
            {
                services.AddHttpClient(); // This fails to resolve HttpClient
                //services.AddSingleton<HttpClient>(provider => new HttpClient());    //This resolves okay
                services.AddSingleton<TestClass>();
            });

Classes requiring HttpClient which fail to resolve

    public class TestClass : ITestClass
{
    public TestClass(HttpClient client)
    {

    }
}

public interface ITestClass
{
}

You are looking for a typed client. AddHttpClient just adds the factory — Nkosi
– Nkosi, Commented Oct 16, 2019 at 18:39

Nkosi · Accepted Answer · 2019-10-16 18:56:21Z

1

AddHttpClient just adds the factory

You are looking for a typed client.

//...
.ConfigureServices((hostContext, services) => {
    services.AddHttpClient<ITestClass, TestClass>();

})
//...

edited Oct 16, 2019 at 18:56

answered Oct 16, 2019 at 18:42

Nkosi

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1 Comment

DJM Over a year ago

apologies, may of misunderstood your answer, if I add your line to my solution then that works.

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