2

I am struggling to get the DI to work for IHttpClientFactory in autofac.

Usually I work with the .net core dependency injection system and I do this:

services.AddHttpClient(HttpClientConstants.HttpClientNameA, client =>
            {
                client.BaseAddress = new Uri(MyConfig.MyBaseUrl);
            });

But, now I am working with a Net framework project that uses Autofac. I have looked in internet and as per the tutorials I have found I have tried this:

builder.Register(ctx => new HttpClient() { BaseAddress = new Uri(MyConfig.MyBaseUrl) })
                .Named<HttpClient>(HttpClientConstants.HttpClientNameA)
                .SingleInstance();

            builder.Register(c => c.Resolve<IHttpClientFactory>().CreateClient())
            .As<HttpClient>();
builder.RegisterType<MyService>().As<IMyService>();

But when I try to use it like that it crashes on me, and I get an Autofac error stating that it cannot find a constructor to build my service.

public class MyService: IMyService
    {
        
        private readonly IHttpClientFactory httpClientFactory;

        public MyService(IHttpClientFactory httpClientFactory)
        {
            this.httpClientFactory = httpClientFactory; 
        }
    }

Any idea how can I get it work? It is even possible or shouldn´t I use the IHttpClientFactory at all and use a different approach? (like injecting the httpclient directly int he constructor)

Peter Csala
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Art
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2 Answers2

3

I've succeed to register the factory within a .netStandard 2.0 lib this way :

containerBuilder.Register<IHttpClientFactory>(_ =>
            {
                var services = new ServiceCollection();
                services.AddHttpClient();
                var provider = services.BuildServiceProvider();
                return provider.GetRequiredService<IHttpClientFactory>();
            });

The ServiceCollection is in the namespace 'Microsoft.Extensions.DependencyInjection' that should be available in .net framework using this nuget package.

EtienneP
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    As far as I remember IHttpClientFactory is registered as a singleton internally. It would improve performance to register this as .SingleInstance() too within Autofac. – Cyril Durand Sep 08 '22 at 12:47
0

A cleaner way would be the following:

// Startup.cs
public void ConfigureServices(IServiceCollection services)
{
   services.AddHttpClient();
}

Then register like this:

      builder.Register(c => c.Resolve<IHttpClientFactory>().CreateClient())
            .As<HttpClient>().SingleInstance();

Now you will have both IHttpClientFactory registered and every HttpClient is automatically resolved from the IHttpClientFactory

Jason Landbridge
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