Develop Reference

How to create correct post-request on C#?

I have a site on localhost created to learn how to send http requests, I send a post request to it, trying to simulate sending data via forms, as a response I expect that the data I sent will be added to the database, as it happens when sending via forms, but this does not happen. I assume that I am sending the post request incorrectly and something is missing in it
The site: localhost site
Post request: Pose request headers and data
My C# code:
using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Threading.Tasks;
namespace AirParsingScript
{
class Program
{
private static readonly HttpClient Client = new HttpClient();
static async Task Main()
{
var values = new Dictionary<string, string>
{
{ "Person.DocId_pre", "421" },
{ "Person.DocId", "ADGAGSA" },
{ "Person.Email", "4124421" },
{ "Person.TeleNumber", "4444" }
};
var content = new FormUrlEncodedContent(values);
var response = await Client.PostAsync("https://localhost:44391", content);
var responseString = await Client.GetStringAsync("https://localhost:44391");
// var responseString = await response.Content.ReadAsStringAsync();
Console.WriteLine(responseString);
}
}
}

Create Work Item using Azure DevOps Rest API using C#

I am unable to create Work Item using Azure DevOps REST API as mentioned in Work Items - Create
Request:
https://dev.azure.com/{organization}/MyTestProject/_apis/wit/workitems/$Task?api-version=6.0-preview.3
Request Body:
[
{
"op": "add",
"path": "/fields/System.Title",
"value": "Task2"
}
]
Code to Get Response (Note this code works for all other POST Requests):
using (HttpResponseMessage response = client.SendAsync(requestMessage).Result)
{
response.EnsureSuccessStatusCode();
JsonResponse = await response.Content.ReadAsStringAsync();
}
Response: 400
Can someone please suggest?

It might be helpful to see your full example. However, here is a working example with Newtonsoft.Json (do not forget to create your PAT create personal access token):
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApp2
{
class Program
{
static void Main(string[] args)
{
string PAT = "<personal access token>"; //https://learn.microsoft.com/en-us/azure/devops/organizations/accounts/use-personal-access-tokens-to-authenticate?view=azure-devops&tabs=preview-page
string requestUrl = "https://dev.azure.com/<my_org>/<my_project>/_apis/wit/workitems/$Task?api-version=5.0";
try
{
List<Object> flds = new List<Object>
{
new { op = "add", path = "/fields/System.Title", value = "Title" }
};
string json = JsonConvert.SerializeObject(flds);
HttpClientHandler _httpclienthndlr = new HttpClientHandler();
using (HttpClient client = new HttpClient(_httpclienthndlr))
{
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(
System.Text.ASCIIEncoding.ASCII.GetBytes(
string.Format("{0}:{1}", "", PAT))));
var request = new HttpRequestMessage(new HttpMethod("PATCH"), requestUrl)
{
Content = new StringContent(json, Encoding.UTF8, "application/json-patch+json")
};
HttpResponseMessage responseMessage = client.SendAsync(request).Result;
}
}
catch (Exception ex)
{
}
}
}
}
Additionally, you can consider to use .NET client libraries for Azure DevOps and TFS. Here is the example: Create a bug in Azure DevOps Services using .NET client libraries

application/json-patch+json is required.

Make my own API capable of requesting from another API

I have an existing and functioning API, which now have to be able to get data from another external API. How do i do that best?
I have tried with using HTTPClient, but i can't seem to get it to work. The error i get:
"No MediaTypeFormatter is available to read an object of type 'IList`1' from content with media type 'text/html'." -> I get this error on line 37. Can you spot it and/or tell me how I can do this differently, taking into account that all i want is the data (From the external API) and not to display it using a view, as this is an API?
Code below. I have also created a Pastebin: https://pastebin.com/MuKjEVys
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Net;
namespace API.Controllers
{
[ApiVersion("1.0")]
[Route("api/v{version:apiVersion}/[controller]")]
[ApiController]
public class ExternalApiController : Controller
{
private string ExternalApiLink = "https://blablabla.com/api";
private string ExternalApiLinkGet = "/module/1/";
[HttpGet("getdata")]
public ActionResult<ExternalApi> GetDataFromExternal()
{
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(ExternalApiLink);
var requestApi = client.GetAsync(ExternalApiLinkGet);
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "XXXX");
requestApi.Wait();
var resultFromApi = requestApi.Result;
if (resultFromApi.IsSuccessStatusCode)
{
var readResponse = resultFromApi.Content.ReadAsAsync<IList<ExternalApi>>();
readResponse.Wait();
var data = readResponse.Result;
return Json(data);
}else
{
return NotFound();
}
}
}
}
}

Your response content seems to be json, while the content-type is text/html. If that is the case, the first thing to do would be to call the party that is exposing the service and have them fix it. In the meantime you could just read the content of the response as a string, and deserialize that string:
// Note that I made this method async.
public async Task<IActionResult> GetDataFromExternal()
{
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(ExternalApiLink);
// note that I moved this line above the GetAsync method.
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "XXXX");
// note that I'm disposing the response
using (var response = await client.GetAsync(ExternalApiLinkGet))
{
if (response.IsSuccessStatusCode)
{
// Since the response content is json, but the content-type
// is text/html, simply read the content as a string.
string content = await response.ReadAsStringAsync();
// You can return the actual received content like below,
// or you may deserialize the content before returning to make
// sure it is correct, using JsonConvert.DeserializeObject<List<ExternalApi>>()
// var data = JsonConvert.DeserializeObject<List<ExternalApi>>(content);
// return Json(data);
return Content(content, "application/json");
}
else
{
return NotFound();
}
}
}
}

Compiler Error Consuming Web API Call

I need to implement a webapi call into a legacy ASP.Net Web Forms application.
I know not all of the usings are need for this method but they are for other methods on the page i included on the off chance that one of them is causing the problem.
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Newtonsoft.Json;
using System.Net.Http;
using System.Net.Http.Headers;
private string GetToken(string Username, string IpAddress)
{
string result = string.Empty;
HttpClient client = new HttpClient();
client.BaseAddress = new Uri(SSOApiUri);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = client.GetAsync("api/yourcustomobjects").Result;
if (response.IsSuccessStatusCode)
{
***var data = await response.Content.ReadAsStringAsync();***
var token = JsonConvert.DeserializeObject<GetSSOTokenResponse>(data);
result = token.Token;
}
return result;
}
When I try to compile my application I get the following error at the emphisized line:
Error 19 The 'await' operator can only be used within an async method.
Consider marking this method with the 'async' modifier and changing
its return type to 'Task< string>'.
I am trying to implement a solution similar to the one found in this question but it is failing. I need to call the WebAPI Method, and return part of the result as a string... not a Task< String>

The error is straightforward. You must have an async method to use the await keyword. Your return value will automatically be wrapped in a Task as a result by the compiler. Note that the .Result can be changed to an await as well. Here's the Microsoft documentation on the async/await keywords
private async Task<string> GetToken(string Username, string IpAddress)
{
string result = string.Empty;
HttpClient client = new HttpClient();
client.BaseAddress = new Uri(SSOApiUri);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = await client.GetAsync("api/yourcustomobjects");
if (response.IsSuccessStatusCode)
{
var data = await response.Content.ReadAsStringAsync();
var token = JsonConvert.DeserializeObject<GetSSOTokenResponse>(data);
result = token.Token;
}
return result;
}

Getting an UTF-8 response with httpclient in Windows Store apps

I'm building a Windows Store app, but I'm stuck at getting a UTF-8 response from an API.
This is the code:
using (HttpClient client = new HttpClient())
{
Uri url = new Uri(BaseUrl + "/me/lists");
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/json");
HttpResponseMessage response = await client.SendRequestAsync(request);
response.EnsureSuccessStatusCode();
string responseString = await response.Content.ReadAsStringAsync();
response.Dispose();
}
The reponseString always contains strange characters which should be accents like é, and I tried using a stream, but the API I found in some examples don't exist in Windows RT.
Edit: improved code, still same problem.

Instead of using response.Content.ReadAsStringAsync() directly you could use response.Content.ReadAsBufferAsync() pointed by #Kiewic as follows:
var buffer = await response.Content.ReadAsBufferAsync();
var byteArray = buffer.ToArray();
var responseString = Encoding.UTF8.GetString(byteArray, 0, byteArray.Length);
This is working in my case and I guess that using UTF8 should solve most of the issues. Now go figure why there is no way to do this using ReadAsStringAsync :)

Solved it like this:
using (HttpClient client = new HttpClient())
{
using (HttpResponseMessage response = await client.GetAsync(url))
{
var byteArray = await response.Content.ReadAsByteArrayAsync();
var result = Encoding.UTF8.GetString(byteArray, 0, byteArray.Length);
return result;
}
}

I like El Marchewko's approach of using an extension, but the code did not work for me. This did:
using System.IO;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
namespace WannaSport.Data.Integration
{
public static class HttpContentExtension
{
public static async Task<string> ReadAsStringUTF8Async(this HttpContent content)
{
return await content.ReadAsStringAsync(Encoding.UTF8);
}
public static async Task<string> ReadAsStringAsync(this HttpContent content, Encoding encoding)
{
using (var reader = new StreamReader((await content.ReadAsStreamAsync()), encoding))
{
return reader.ReadToEnd();
}
}
}
}

Perhaps the problem is that the response is zipped. If the content type is gzip, you will need decompress the response in to a string. Some servers do this to save bandwidth which is normally fine. In .NET Core and probably .NET Framework, this will automatically unzip the response. But this does not work in UWP. This seems like a glaring bug in UWP to me.
string responseString = await response.Content.ReadAsStringAsync();
This thread gives a clear example of how to decompress the response:
Compression/Decompression string with C#

The HttpClient doesn't give you a lot of flexibility.
You can use a HttpWebRequest instead and get the raw bytes from the response using HttpWebResponse.GetResponseStream().

Can't comment yet, so I'll have to add my thoughts here.
You could try to use _client.GetStringAsync(url) as #cremor suggested, and set your authentication headers using the _client.DefaultRequestHeaders property.
Alternatively, you could also try to use the ReadAsByteArrayAsync method on the response.Content object and use System.Text.Encoding to decode that byte array to a UTF-8 string.

My approach using an Extension:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Web.Http;
namespace yourfancyNamespace
{
public static class IHttpContentExtension
{
public static async Task<string> ReadAsStringUTF8Async(this IHttpContent content)
{
return await content.ReadAsStringAsync(Encoding.UTF8);
}
public static async Task<string> ReadAsStringAsync(this IHttpContent content, Encoding encoding)
{
using (TextReader reader = new StreamReader((await content.ReadAsInputStreamAsync()).AsStreamForRead(), encoding))
{
return reader.ReadToEnd();
}
}
}
}