How do I get result from post to web API?

Question

1.00/5 (3 votes)

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I'm posting to web API, but it keeps loading the page without any response...

What I have tried:

First I tried this code after putting my url, email, key and service:

public async Task<string> Login()
       {
           using (var client = new HttpClient())
           {
               client.BaseAddress = new Uri("my url");
               var content = new FormUrlEncodedContent(new[]
               {
                   new KeyValuePair<string,string>("email","my email"),
                   new KeyValuePair<string,string>("api_key","my key"),

               });
               HttpResponseMessage rm = await client.PostAsync("my service", content);
               if(rm.IsSuccessStatusCode)
               {
                   return await rm.Content.ReadAsStringAsync();
               }
               return "No response";
           }
       }

Then, I changed my code and tried this one:

public async Task<string> Login()
      {
          HttpClient httpClient = new HttpClient();
          HttpRequestMessage request = new HttpRequestMessage();
          request.RequestUri = new Uri("my url and service");
          request.Method = HttpMethod.Get;
          request.Headers.Add("email", "my email");
          request.Headers.Add("api_key", "my key");
          HttpResponseMessage response = await httpClient.SendAsync(request);
          var responseString = await response.Content.ReadAsStringAsync();
          var statusCode = response.StatusCode;
          return statusCode.ToString();
      }

But also no any response except keep loading the page, in debug mode it reach to this line:

HttpResponseMessage response = await httpClient.SendAsync(request);

Any ideas?
--------------------
edit:
--------------------
It was a problem in my code, this is the correct code:

HttpClient httpClient = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage();
request.RequestUri = new Uri("my url");
request.Method = HttpMethod.Post;
request.Headers.Add("email", "my email");
request.Headers.Add("api_key", "my api_key");
HttpResponseMessage response = httpClient.SendAsync(request).Result;
var responseString =  response.Content.ReadAsStringAsync();

Posted 12-Apr-23 3:31am

Ahmad Yousef 2021

Updated 15-Apr-23 14:30pm

v2

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Comments

[no name] 12-Apr-23 12:46pm

Use strings (with values) instead of literals. You really can't keep track of your parameters any other way (which is probably the issue).

Ahmad Yousef 2021 14-Apr-23 5:09am

I tried to pass variables to function, same results...

mtoha 12-Apr-23 21:21pm

are you sure post parameters sent is api_key and email?
are you sure with your url?

Ahmad Yousef 2021 14-Apr-23 5:10am

Yes, the request header must contain email and api_key

Graeme_Grant 15-Apr-23 1:48am

You should not be doing this for multiple reasons, resources will deplete.

HttpClient httpClient = new HttpClient();

Use IHttpClientFactory.

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Graeme_Grant · Answer 1 · 2023-04-14T20:48:00

Solution 3

I mentioned above that you should use IHttpFactory. Here is a minimal implementation (.Net 3.1+):

C#

IHttpClientFactory InitializeHttpClientFactory()
{
    ServiceCollection builder = new();

    builder.AddHttpClient();

    ServiceProvider serviceProvider = builder.BuildServiceProvider();
    return serviceProvider.GetRequiredService<IHttpClientFactory>();
}

Then you can store a concrete implementation:

C#

IHttpClientFactory _httpClientFactory = InitializeHttpClientFactory();

and to use:

C#

using HttpClient client = _httpClientFactory!.CreateClient();

UPDATE
Here: NuGet Gallery | Microsoft.Extensions.Http 8.0.0-preview.3.23174.8[^] (edit: you can use other versions other than 8.0.0.0 preview, just what Google found)

Also, if your IDE is complaining: NuGet Gallery | Microsoft.Extensions.DependencyInjection 7.0.0[^]

Posted 14-Apr-23 20:48pm

Graeme_Grant

Updated 15-Apr-23 14:34pm

v3

Comments

Ahmad Yousef 2021 15-Apr-23 20:25pm

My code is working now, but I want to use this, what nuget package I shall use for IHttpClientFactory class please... is it Microsoft.Extensions.Http 7.0.0?

Graeme_Grant 15-Apr-23 20:31pm

See the update.

Ahmad Yousef 2021 16-Apr-23 4:05am

I did some changes, it worked after that using Microsoft.Extensions.Http 7.0.0, like:

public static IHttpClientFactory InitializeHttpClientFactory()

public static IHttpClientFactory _httpClientFactory = InitializeHttpClientFactory();

HttpClient httpClient = _httpClientFactory.CreateClient();

Graeme_Grant 16-Apr-23 4:12am

There is an error in your last post:

HttpClient httpClient = new HttpClient();

should be:

using HttpClient client = _httpClientFactory.CreateClient();

or:

using HttpClient client = _httpClientFactory.CreateClient()
{
    // do work here
}

BTW, nowhere did you mention which version of .Net you were working with. This was fixing your memory leak / OS resource consumption issue. The code was pulled from a working console app written in .Net 7 ... for older .Net Framework 4, yes, they need to be static when used in a console add in the program class ... vote of 3 because of no static keyword is a bit underhanded. The code fixes your poor implementation, regardless of the 'static' keyword. If wrapped in a handler class, no static keyword would be used.

Ahmad Yousef 2021 16-Apr-23 10:47am

I'm working on asp.net webform...
Unfortunately "using" statement didn't work...
vote of 3 because my problem was different and I've solved it, but you have assisted me in this new way, and I'm grateful!

Graeme_Grant 16-Apr-23 11:11am

Asp.Net? Even more reason to change to IHttpClientFactory. If not your website will crash. A bigger problem & solution to the issue that you are having! This would have been even harder to resolve.

Look at the 2nd example for the Using statement. The first version is a modern C#11 syntax. The Using statement is to prevent memory leaks. If not using the Using statement, then you need to manually dispose with

client.Dispose();

As for the original issue that you have asked for help with, there is not enough information given to answer the question asked. We have no idea of the requirements for the API that you are trying to connect to.

mtoha · Answer 2 · 2023-04-12T15:26:00

try to use this functions:

C#

public async Task<M> ConnectHttpClient<R, M>(string apiUrl, R reqModel)
{
    M model = default(M);

    HttpClient client = new HttpClient();
    client.BaseAddress = new Uri(baseUrl);
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    HttpResponseMessage response = await client.PostAsJsonAsync(apiUrl, reqModel);
    if (response.IsSuccessStatusCode)
    {
        var res = response.Content.ReadAsStringAsync().Result;
        model = JsonConvert.DeserializeObject<M>(res);
    }
    return model;
}

public async Task<M> ConnectRestClient<R, M>(string apiUrl, R reqModel)
        {
            M model = default(M);

            RestClient restClient = new RestClient(apiUrl);
            RestRequest restRequest = new RestRequest(apiUrl, RestSharp.Method.Post);
            restRequest.AddParameter(
               "application/json",
               JsonConvert.SerializeObject(reqModel),
               ParameterType.RequestBody);
            RestResponse restResponse = await restClient.ExecuteAsync(restRequest);
            if (restResponse.IsSuccessful)
            {
                string response = restResponse.Content;
                model = JsonConvert.DeserializeObject<M>(response);
            }
            return model;
        }

example usage :

//example code
var result1 = await service.ConnectHttpClient<User, List<User>>("api/User/GetUserInfoByUserId", new User() { UserId = 1 });
var result2 = await service.ConnectRestClient<User, List<User>>("api/User/GetUserInfoByUserId", new User() { UserId = 1 });

Pete O'Hanlon · Answer 3 · 2023-04-14T01:55:00

The two pieces of code you show are not equivalent. In the first instance, you pass the parameters as a post body. In the second instance, you add them as headers to a GET request. Which is it? Are they headers on a get or are they a post body? Is the API you are trying to connect to, accessible with the verb you are using?

If I were you, I would try the API call out outside of code first. Download Postman and use that to test the API call. Once you have it successfully working, you will know what to set in your code.

How do I get result from post to web API?

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