C#•14mo ago

✅ DI with HttpClient / HttpClientFactory

The docs show the basic usage of HttpClientFactory with DI as follows:

public class SomeService{
  private IHttpClientFactory _httpFactory;
  public SomeService(IHttpClientFactory httpFactory){
    _httpFactory = httpFactory;
  }
  public void Method1(){
    var client = _httpFactory.CreateClient();
    //use client to do something
  }
  public void Method2(){
    var client = _httpFactory.CreateClient();
    //use client to do something
  }
}

public class SomeService{
  private IHttpClientFactory _httpFactory;
  public SomeService(IHttpClientFactory httpFactory){
    _httpFactory = httpFactory;
  }
  public void Method1(){
    var client = _httpFactory.CreateClient();
    //use client to do something
  }
  public void Method2(){
    var client = _httpFactory.CreateClient();
    //use client to do something
  }
}

I wonder why not do something like this instead:

public class SomeService{
   private HttpClient _client;
   public SomeService(IHttpClientFactory httpFactory){
      _client = httpFactory.CreateClient();
   }
   public void Method1(){
      //use client to do something
   }
   public void Method1(){
      //use client to do something
   }
}

public class SomeService{
   private HttpClient _client;
   public SomeService(IHttpClientFactory httpFactory){
      _client = httpFactory.CreateClient();
   }
   public void Method1(){
      //use client to do something
   }
   public void Method1(){
      //use client to do something
   }
}

like why work with local variable and invoke CreateClient() multiple times?

72 Replies

Florian Voß•14mo ago

as far as I understand it won't create a new instance everytime its called but reuse an httpClient as much as possible instead which makes it even more confusing for me why we call it multiple times rather than just once

júlio•14mo ago

It's a sort of Singleton from what I understand So it's the same thing It's not creating new a HttpClient, it's reusing a internal HttpClient instance for you That the Factory manages maybe it would be even better not to hold the reference and just call the .CreateClient since its a resource the Factory manages, maybe you should avoid having a reference to it with the duration of the service, but could be harmless, not sure

Unknown User•14mo ago

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júlio•14mo ago

Why?

Unknown User•14mo ago

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júlio•14mo ago

Isn't the HttpClientHandler deprecated?

Unknown User•14mo ago

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júlio•14mo ago

I dont have any, it was just the feeling I got when trying to migrate things and reading from docs

Unknown User•14mo ago

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júlio•14mo ago

Im actually having a understanding issue also regarding the IHttpClientFactory interface I made a thread for it tho, if you maybe have time https://discord.com/channels/143867839282020352/1113391788204498976

Unknown User•14mo ago

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júlio•14mo ago

Im not even sure its being handled in the original code

Unknown User•14mo ago

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júlio•14mo ago

I think that the things they communicate to care about cookie

Unknown User•14mo ago

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júlio•14mo ago

no no i was talking about smethng else

Unknown User•14mo ago

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júlio•14mo ago

not related to the OP question

Unknown User•14mo ago

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júlio•14mo ago

I was talking about this: https://discord.com/channels/143867839282020352/1113391788204498976

Unknown User•14mo ago

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júlio•14mo ago

I think that approach is nice cause you give it the host so if host changes you just go there and fix

Unknown User•14mo ago

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júlio•14mo ago

I think its a issue to have so many different things that all work cause you never know which one to pick

MODiX•14mo ago

https://discord.com/channels/143867839282020352/751510709162213406/876886910545580122

MODiX•14mo ago

tebeco#0205

    public class CorrelationIdHandler : DelegatingHandler
    {
        private readonly ThisHttpClientOptions _httpClientOptions;
        private readonly ICorrelationIdAccessor _correlationIdAccessor;

        public CorrelationIdHandler(IOption<ThisHttpClientOptions> httpClientOptions, ICorrelationIdAccessor correlationIdAccessor)
        {
            _httpClientOptions = httpClientOptions.Value;
            _correlationIdAccessor = correlationIdAccessor;
        }

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            if (!_httpClientOptions.Correlation.Enabled)
            {
                return await base.SendAsync(request, cancellationToken);
            }

            IList<string> correlationId = _correlationIdAccessor.CorrelationId;
            if (correlationId.Count > 0)
            {
                request.Headers.Add(_configuration.Header, correlationId);
            }

            return await base.SendAsync(request, cancellationToken);
        }
    }

    public class CorrelationIdHandler : DelegatingHandler
    {
        private readonly ThisHttpClientOptions _httpClientOptions;
        private readonly ICorrelationIdAccessor _correlationIdAccessor;

        public CorrelationIdHandler(IOption<ThisHttpClientOptions> httpClientOptions, ICorrelationIdAccessor correlationIdAccessor)
        {
            _httpClientOptions = httpClientOptions.Value;
            _correlationIdAccessor = correlationIdAccessor;
        }

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            if (!_httpClientOptions.Correlation.Enabled)
            {
                return await base.SendAsync(request, cancellationToken);
            }

            IList<string> correlationId = _correlationIdAccessor.CorrelationId;
            if (correlationId.Count > 0)
            {
                request.Headers.Add(_configuration.Header, correlationId);
            }

            return await base.SendAsync(request, cancellationToken);
        }
    }

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Unknown User•14mo ago

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júlio•14mo ago

translate to noob please

Unknown User•14mo ago

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júlio•14mo ago

Unknown User•14mo ago

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júlio•14mo ago

So the requests client makes to my service is a incoming request, and the resquests my service makes to the outside are outcoming requests?

Unknown User•14mo ago

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Florian Voß•14mo ago

what I don't understand about TypedClient is this @TeBeClone: A Typed client is pretty much a Service that uses HttpClient right? So in your code here, FooService is a service that uses HttpClient. Now FooService is what I am writing right now and I wanna know how to inject HttpClient into FooService

Unknown User•14mo ago

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Florian Voß•14mo ago

okay but what I'm asking is not how to inject FooHttpService or FooHttpClient or whatever into services that consume it but instead I'm asking how to inject HttpClient into FooHttpService / FooHttpClient

Unknown User•14mo ago

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Florian Voß•14mo ago

so this SomeService here is the FooHttpClient that I wanna inject HttpClient into if that makes sense

Unknown User•14mo ago

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júlio•14mo ago

can you give a real world example? I thought it only needed a controller and a httpclient

Florian Voß•14mo ago

ok but how do you inject httpclient into the typed client

Unknown User•14mo ago

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Florian Voß•14mo ago

however you do this, I will do it like that in the Service directly and skip the Typed Client layer that was my plan

Unknown User•14mo ago

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Florian Voß•14mo ago

I know

Unknown User•14mo ago

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Florian Voß•14mo ago

you are kinda doding my question tho the question is how you inject the HttpClient into the FooHttpClient I know how to inject FooHttpClient into FooService and how to inject FooService into Controllers

Unknown User•14mo ago

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Florian Voß•14mo ago

but its not shown in here you only inject FooService and FooHttpClient. How does FooHttpClient get its HttpClient dependency?

Unknown User•14mo ago

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Florian Voß•14mo ago

ohhh that part I didn't know

Unknown User•14mo ago

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Florian Voß•14mo ago

its getting clearer and clearer for me, thx a lot

Unknown User•14mo ago

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Florian Voß•14mo ago

now in my case to get a little more concrete on the topic, I am writing WPF app and I wanna fetch Tickets from third party Api. There isn't really any business logic that needs to get applied on those tickets, I pretty much just yeet them into the UI. so the TicketService kinda is also the TicketHttpClient at the same time, is that fine? and then my MainWindow.xaml.cs consumes the TicketService / TicketHttpClient to display the tickets

Unknown User•14mo ago

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Florian Voß•14mo ago

pretty much:

public class TicketService{
   private HttpClient _client;
   public TicketService(HttpClient client){
     _client = client;
   }
   public async Task<List<TicketDTO>> GetLastAcceptedAsync(){}
   public async Task<List<TicketDTO>> GetMissedAsync(){}
   etc.
}
public partial class MainWindow(){
   private TicketService _ticketSerivce;
   public MainWindow(TicketService ticketService){
      _ticketService = ticketService;
   }
}

public class TicketService{
   private HttpClient _client;
   public TicketService(HttpClient client){
     _client = client;
   }
   public async Task<List<TicketDTO>> GetLastAcceptedAsync(){}
   public async Task<List<TicketDTO>> GetMissedAsync(){}
   etc.
}
public partial class MainWindow(){
   private TicketService _ticketSerivce;
   public MainWindow(TicketService ticketService){
      _ticketService = ticketService;
   }
}

builder.Services.AddHttpClient<TicketService>() That should work and is good design right? Should we name it TicketService or better TicketHttpClient or smth, its kinda all of that at same time

Unknown User•14mo ago

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Florian Voß•14mo ago

I am patient, answer me later 🙂 yep

Unknown User•14mo ago

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Florian Voß•14mo ago

that is already implemented, don't worry added all Microsfot Extensions that are needed

Unknown User•14mo ago

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Florian Voß•14mo ago

I don't really have models in that sense, I made seperation between Entities and DTOs

Unknown User•14mo ago

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Florian Voß•14mo ago

Entities for DB and DTO for any data transfer such as between different layers of my app or even beyond that

Unknown User•14mo ago

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Florian Voß•14mo ago

okay but we also suffix services with Service for the same reason and its both the TicketHttpClient and the TicketService in one type 🤷 as fetching is all I need / no business logic required

Unknown User•14mo ago

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Florian Voß•14mo ago

I just need Mainwindow => TicketService / TicketHttpClient. There is no Business logic that needs to get applied on the stuff we get from external world so I guess i just name it TicketHttpClient then and we have no Service

Unknown User•14mo ago

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Florian Voß•14mo ago

okk

MODiX•14mo ago

tebeco#0205

and if you have ANY FORM of logic that is not linked to making request

Quoted by

<@!689473681302224947> from #DI with HttpClient / HttpClientFactory (click here)

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✅ DI with HttpClient / HttpClientFactory