Generic Interface Dependency injection in .Net Core

Question

I have the below Generic Class & Interface implementations

public interface IHttpClient<T> where T : class
{
   public Task<List<T>> GetJsonAsync(string url);
}


public class HttpClient<T> : IHttpClient<T> where T:class
{
    private readonly IHttpClientFactory _clientFactory;

    public HttpClient(IHttpClientFactory clientFactory)
    {
        _clientFactory = clientFactory;
    }

  

    public async Task<List<T>> GetJsonAsync(string url)
    {
        var request = new HttpRequestMessage(HttpMethod.Get,url);
        var client = _clientFactory.CreateClient();

        var response = await client.SendAsync(request);

        if (response.IsSuccessStatusCode)
        {
            var result = await response.Content.ReadAsStringAsync();
            return JsonConvert.DeserializeObject<List<T>>(result);
        }

        return null;
    }
     
}

and this is how I try to register them in the startup.cs

 public void ConfigureServices(IServiceCollection services)
 {      
     services.AddScoped(typeof(IHttpClient<>), typeof(HttpClient<>));
 }

My Controller:

  private readonly IHttpClient<Feed> _feedClient;
  public HomeController( IHttpClient<Feed> _client)
    {
       
        _feedClient = _client;

      
    }

and this is the error I'm getting

InvalidOperationException: Unable to resolve service for type 'System.Net.Http.IHttpClientFactory' while attempting to activate...

what is it that I'm missing? any help is very appreciated..

Thank you Knoop, it worked smoothly after adding the code =)) — Asım Gündüz
– Asım Gündüz, Commented Jul 30, 2020 at 13:33

Farhad Zamani · Accepted Answer · 2020-07-30 13:33:36Z

1

You should register HttpClient in startup class like this

//register
services.AddHttpClient();

use

public YourController(IHttpClientFactory httpClientFactory)
{ 
    _httpClientFactory = httpClientFactory;
}
var client = _httpClientFactory.CreateClient();

Another options

//register
services.AddHttpClient("YourClientName", c =>
{
    c.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    c.BaseAddress = new Uri("https://yoururl");
});

use

public YourController(IHttpClientFactory httpClientFactory)
{ 
    _httpClientFactory = httpClientFactory;
}
var client = _httpClientFactory.CreateClient("YourClientName");

answered Jul 30, 2020 at 13:33

Farhad Zamani

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