Develop Reference

C# Creating Equivalent HttpRequestMessage for HttpWebRequest code

I was told to migrate a post request written in HttpWebRequest to HttpRequestMessage.
I've provided the old code and the new code that I've developed below.
In the old code they are sending the byte stream over to the
endpoint. I'm not sure whether using HttpWebRequest demands data to be sent as bytes or not.
In the new code, I've created a StringContent to be sent to the endpoint. Are both the codes equivalent and works the intended way?
If not, some help to modify the new code is appreciated.
Using HttpWebRequest (old code)
//postData -> data to be sent(type string)
HttpWebRequest req = (HttpWebRequest)WebRequest.Create("someurl.net");
req.ContentType = "application/xml";
req.Accept = "application/xml";
byte[] postBytes = Encoding.UTF8.GetBytes(postData);
req.ContentLength = postBytes.Length;
Stream postStream = req.GetRequestStream();
postStream.Write(postBytes, 0, postBytes.Length);
postStream.Flush();
postStream.Close();
WebResponse resp = req.GetResponse();
Using HttpRequestMessage (new code)
//postData -> data to be sent(type string)
var request = new HttpRequestMessage(HttpMethod.Post, $"{address}");
request.Headers.Add("Accept", "application/xml");
request.Headers.Add("Content-Type", "application/xml");
request.Content = new StringContent(RSAEncryptDecrypt.EncryptResponse(postData));
await _client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken)

I suppose it depends on what the intent was originally :-)
HttpWebRequest is very flexible to what it will send out. Byte[], FormUrlEncodedContent, Multipart Content, Stream, String, ...you get the idea.
There are some performance considerations, again depending on your content. End of the day if you test it and it passes within the required parameters, then you should be OK. Given someone is telling you to do it, it might be in your best interest to ask said someone a few additional questions.
One thing that does stick out to me, in the original code your string is encoded in UTF8 and your new code appears to perhaps be something else. May want to explicitly call out the encoding parameter of StringContent if you choose to keep going that way.
Here's a quick example that should get you up and going. A little inflated, but hopefully it helps you out :-)
public static void PostSomeContent(string data_parameter, string uri_parameter){
HttpRequestMessage _httpRequestMessage;
MemoryStream _memoryStream;
StreamWriter _streamWriter;
StreamContent _streamContent;
HttpClient _client;
HttpResponseMessage _httpResponse;
//Initilize a HttpRequest Message
_httpRequestMessage =
new HttpRequestMessage();
//Set the end point
//You could also do this in the intilization
_httpRequestMessage.RequestUri =
new Uri(uri_parameter);
//Set your headers
_httpRequestMessage.Headers.Add("Accept", "application/xml");
_httpRequestMessage.Headers.Add("Content-Type", "application/xml");
//Set the methood
_httpRequestMessage.Method =
HttpMethod.Post;
//I'm asuming you want it to be async
Task.Run(async()=>{
//Set up the stream
using(_memoryStream = new MemoryStream()){
using(_streamWriter = new StreamWriter(_memoryStream)){
_streamWriter.Write(data_parameter);
_streamWriter.Flush();
_memoryStream.Seek(
offset:0,
loc: System.IO.SeekOrigin.Begin
);
using(_streamContent = new StreamContent(_memoryStream)){
_httpRequestMessage.Content = _streamContent;
_client =
new HttpClient();
try{
//Use the client to send your message
//Configure what you want back via completion option
using(_httpResponse = await _client.SendAsync(
request: _httpRequestMessage,
completionOption: HttpCompletionOption.ResponseHeadersRead)){
//Or however you would like to make sure there was no error
_httpResponse.EnsureSuccessStatusCode();
//If you want the response as a string:
string _content = await _httpResponse.Content.ReadAsStringAsync();
//Or response in a stream:
using(Stream _responseStream = await _httpResponse.Content.ReadAsStreamAsync()){
}
}
}
catch(Exception){
//Handle your exception
}
}
}
}
});
}

.Net Core 3.1 Api Integration Test of DELETE Request with body [duplicate]

I have a scenario where I need to call my Web API Delete method constructed like the following:
// DELETE: api/products/{id}/headers
[HttpDelete("{id}/headers")]
public void DeleteProductHeaders(int id, [FromBody] string query)
{
}
The trick is that in order to get the query over I need to send it through the body and DeleteAsync does not have a param for json like post does. Does anyone know how I can do this using System.Net.Http client in c#?
// Delete a product's headers
public void DeleteProductHeaders(int id, string query)
{
using (var client = GetClient())
{
HttpResponseMessage response;
try
{
// HTTP DELETE
response = client.DeleteAsync($"api/products/{id}/headers").Result;
}
catch (Exception ex)
{
throw new Exception("Unable to connect to the server", ex);
}
}
return retVal;
}

Here is how I accomplished it
var request = new HttpRequestMessage(HttpMethod.Delete, "http://www.example.com/");
request.Content = new StringContent(JsonConvert.SerializeObject(object), Encoding.UTF8, "application/json");
await this.client.SendAsync(request);

I think the reason HttpClient is designed that way is although HTTP 1.1 spec allows message body on DELETE requests, essentially it is not expected to do so as the spec doesn't define any semantics for it as it is defined here. HttpClient strictly follows HTTP spec thus you see it doesn't allow you to add a message body to the request.
So, I think your option from the client side includes using HttpRequestMessage described in here. If you want to fix it from the backend and if your message body would work well in query params you can try that instead of sending the query in message body.
I personally think DELETE should be allowed to have a message body and should not be ignored in a server as there are certainly use cases for that like the one you mentioned here.
In any case for more productive discussion on this please have a look at this.

My API as below:
// DELETE api/values
public void Delete([FromBody]string value)
{
}
Calling from C# server side
string URL = "http://localhost:xxxxx/api/values";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
request.Method = "DELETE";
request.ContentType = "application/json";
string data = Newtonsoft.Json.JsonConvert.SerializeObject("your body parameter value");
request.ContentLength = data.Length;
StreamWriter requestWriter = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
requestWriter.Write(data);
requestWriter.Close();
try
{
WebResponse webResponse = request.GetResponse();
Stream webStream = webResponse.GetResponseStream();
StreamReader responseReader = new StreamReader(webStream);
string response = responseReader.ReadToEnd();
responseReader.Close();
}
catch
{
}

POST API with raw Json using HttpClient in C# [duplicate]

I'm trying to set the Content-Type header of an HttpClient object as required by an API I am calling.
I tried setting the Content-Type like below:
using (var httpClient = new HttpClient())
{
httpClient.BaseAddress = new Uri("http://example.com/");
httpClient.DefaultRequestHeaders.Add("Accept", "application/json");
httpClient.DefaultRequestHeaders.Add("Content-Type", "application/json");
// ...
}
It allows me to add the Accept header but when I try to add Content-Type it throws the following exception:
Misused header name. Make sure request headers are used with
HttpRequestMessage, response headers with HttpResponseMessage, and
content headers with HttpContent objects.
How can I set the Content-Type header in a HttpClient request?

The content type is a header of the content, not of the request, which is why this is failing. AddWithoutValidation as suggested by Robert Levy may work, but you can also set the content type when creating the request content itself (note that the code snippet adds application/json in two places-for Accept and Content-Type headers):
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://example.com/");
client.DefaultRequestHeaders
.Accept
.Add(new MediaTypeWithQualityHeaderValue("application/json"));//ACCEPT header
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "relativeAddress");
request.Content = new StringContent("{\"name\":\"John Doe\",\"age\":33}",
Encoding.UTF8,
"application/json");//CONTENT-TYPE header
client.SendAsync(request)
.ContinueWith(responseTask =>
{
Console.WriteLine("Response: {0}", responseTask.Result);
});

For those who didn't see Johns comment to carlos solution ...
req.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");

If you don't mind a small library dependency, Flurl.Http [disclosure: I'm the author] makes this uber-simple. Its PostJsonAsync method takes care of both serializing the content and setting the content-type header, and ReceiveJson deserializes the response. If the accept header is required you'll need to set that yourself, but Flurl provides a pretty clean way to do that too:
using Flurl.Http;
var result = await "http://example.com/"
.WithHeader("Accept", "application/json")
.PostJsonAsync(new { ... })
.ReceiveJson<TResult>();
Flurl uses HttpClient and Json.NET under the hood, and it's a PCL so it'll work on a variety of platforms.
PM> Install-Package Flurl.Http

try to use TryAddWithoutValidation
var client = new HttpClient();
client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");

.Net tries to force you to obey certain standards, namely that the Content-Type header can only be specified on requests that have content (e.g. POST, PUT, etc.). Therefore, as others have indicated, the preferred way to set the Content-Type header is through the HttpContent.Headers.ContentType property.
With that said, certain APIs (such as the LiquidFiles Api, as of 2016-12-19) requires setting the Content-Type header for a GET request. .Net will not allow setting this header on the request itself -- even using TryAddWithoutValidation. Furthermore, you cannot specify a Content for the request -- even if it is of zero-length. The only way I could seem to get around this was to resort to reflection. The code (in case some else needs it) is
var field = typeof(System.Net.Http.Headers.HttpRequestHeaders)
.GetField("invalidHeaders", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static)
?? typeof(System.Net.Http.Headers.HttpRequestHeaders)
.GetField("s_invalidHeaders", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);
if (field != null)
{
var invalidFields = (HashSet<string>)field.GetValue(null);
invalidFields.Remove("Content-Type");
}
_client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "text/xml");
Edit:
As noted in the comments, this field has different names in different versions of the dll. In the source code on GitHub, the field is currently named s_invalidHeaders. The example has been modified to account for this per the suggestion of #David Thompson.

For those who troubled with charset
I had very special case that the service provider didn't accept charset, and they refuse to change the substructure to allow it...
Unfortunately HttpClient was setting the header automatically through StringContent, and no matter if you pass null or Encoding.UTF8, it will always set the charset...
Today i was on the edge to change the sub-system; moving from HttpClient to anything else, that something came to my mind..., why not use reflection to empty out the "charset"? ...
And before i even try it, i thought of a way, "maybe I can change it after initialization", and that worked.
Here's how you can set the exact "application/json" header without "; charset=utf-8".
var jsonRequest = JsonSerializeObject(req, options); // Custom function that parse object to string
var stringContent = new StringContent(jsonRequest, Encoding.UTF8, "application/json");
stringContent.Headers.ContentType.CharSet = null;
return stringContent;
Note: The null value in following won't work, and append "; charset=utf-8"
return new StringContent(jsonRequest, null, "application/json");
EDIT
#DesertFoxAZ suggests that also the following code can be used and works fine. (didn't test it myself, if it work's rate and credit him in comments)
stringContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");

Some extra information about .NET Core (after reading erdomke's post about setting a private field to supply the content-type on a request that doesn't have content)...
After debugging my code, I can't see the private field to set via reflection - so I thought I'd try to recreate the problem.
I have tried the following code using .Net 4.6:
HttpRequestMessage httpRequest = new HttpRequestMessage(HttpMethod.Get, #"myUrl");
httpRequest.Content = new StringContent(string.Empty, Encoding.UTF8, "application/json");
HttpClient client = new HttpClient();
Task<HttpResponseMessage> response = client.SendAsync(httpRequest); //I know I should have used async/await here!
var result = response.Result;
And, as expected, I get an aggregate exception with the content "Cannot send a content-body with this verb-type."
However, if i do the same thing with .NET Core (1.1) - I don't get an exception. My request was quite happily answered by my server application, and the content-type was picked up.
I was pleasantly surprised about that, and I hope it helps someone!

Call AddWithoutValidation instead of Add (see this MSDN link).
Alternatively, I'm guessing the API you are using really only requires this for POST or PUT requests (not ordinary GET requests). In that case, when you call HttpClient.PostAsync and pass in an HttpContent, set this on the Headers property of that HttpContent object.

The trick is that you can just set all kinds of headers like:
HttpRequestMessage request = new HttpRequestMessage();
request.Headers.Add("Accept-Language", "en"); //works OK
but not any header. For example:
request.Headers.Add("Content-Type", "application/json");//wrong
will raise the run-time exception Misused header name. It may seem that this will work:
request.Headers.Add(
HttpRequestHeader.ContentType.ToString(), //useless
"application/json"
);
but this gives a useless header named ContentType, without the hyphen. Header names are not case-sensitive, but are very hyphen-sensitive.
The solution is to declare the encoding and type of the body when adding the body to the Content part of the http request:
string Body = "...";
request.Content =
new StringContent(Body, Encoding.UTF8, "application/json");
Only then the applicable http header is automatically added to the request:
Content-Type: application/json; charset=utf-8
It was hard to find this out, with Fiddler, on a machine without a proxy server. Visual Studio used to have a Network Tool where you could inspect all headers, but only in version 2015, not in newer versions 2017 or 2022. If you use the debugger to inspect request.Headers, you will not find the header added automagically by StringContent().

var content = new JsonContent();
content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
content.Headers.ContentType.Parameters.Add(new NameValueHeaderValue("charset", "utf-8"));
content.Headers.ContentType.Parameters.Add(new NameValueHeaderValue("IEEE754Compatible", "true"));
It's all what you need.
With using Newtonsoft.Json, if you need a content as json string.
public class JsonContent : HttpContent
{
private readonly MemoryStream _stream = new MemoryStream();
~JsonContent()
{
_stream.Dispose();
}
public JsonContent(object value)
{
Headers.ContentType = new MediaTypeHeaderValue("application/json");
using (var contexStream = new MemoryStream())
using (var jw = new JsonTextWriter(new StreamWriter(contexStream)) { Formatting = Formatting.Indented })
{
var serializer = new JsonSerializer();
serializer.Serialize(jw, value);
jw.Flush();
contexStream.Position = 0;
contexStream.WriteTo(_stream);
}
_stream.Position = 0;
}
private JsonContent(string content)
{
Headers.ContentType = new MediaTypeHeaderValue("application/json");
using (var contexStream = new MemoryStream())
using (var sw = new StreamWriter(contexStream))
{
sw.Write(content);
sw.Flush();
contexStream.Position = 0;
contexStream.WriteTo(_stream);
}
_stream.Position = 0;
}
protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
return _stream.CopyToAsync(stream);
}
protected override bool TryComputeLength(out long length)
{
length = _stream.Length;
return true;
}
public static HttpContent FromFile(string filepath)
{
var content = File.ReadAllText(filepath);
return new JsonContent(content);
}
public string ToJsonString()
{
return Encoding.ASCII.GetString(_stream.GetBuffer(), 0, _stream.GetBuffer().Length).Trim();
}
}

It appears that Microsoft tries to force the developers to follow their standards, without even giving any options or settings to do otherwise, which is really a shame especially given that this is a client and we are dictated by the server side requirements, especially given that Microsoft server side frameworks themselves require it!
So basically Microsoft tries to force us good habits when connecting to their server technologies that force us non good habits...
If anyone from Microsoft is reading this, then please fix it...
Either way for anyone that needs the content-type header for Get etc., while in an older .Net version it is possible to use the answer of #erdomke at https://stackoverflow.com/a/41231353/640195 this unfortunately no longer works in the newer .Net core versions.
The following code has been tested to work with .Net core 3.1 and from the source code on GitHub it looks like it should work with newer .Net versions as well.
private void FixContentTypeHeaders()
{
var assembly = typeof(System.Net.Http.Headers.HttpRequestHeaders).Assembly;
var assemblyTypes = assembly.GetTypes();
var knownHeaderType = assemblyTypes.FirstOrDefault(n => n.Name == "KnownHeader");
var headerTypeField = knownHeaderType?
.GetFields(System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)
.FirstOrDefault(n => n.Name.Contains("HeaderType"));
if (headerTypeField is null) return;
var headerTypeFieldType = headerTypeField.FieldType;
var newValue = Enum.Parse(headerTypeFieldType, "All");
var knownHeadersType = assemblyTypes.FirstOrDefault(n => n.Name == "KnownHeaders");
var contentTypeObj = knownHeadersType.GetFields().FirstOrDefault(n => n.Name == "ContentType").GetValue(null);
if (contentTypeObj is null) return;
headerTypeField.SetValue(contentTypeObj, newValue);
}

You can use this it will be work!
HttpRequestMessage msg = new HttpRequestMessage(HttpMethod.Get,"URL");
msg.Content = new StringContent(string.Empty, Encoding.UTF8, "application/json");
HttpResponseMessage response = await _httpClient.SendAsync(msg);
response.EnsureSuccessStatusCode();
string json = await response.Content.ReadAsStringAsync();

Ok, it's not HTTPClient but if u can use it, WebClient is quite easy:
using (var client = new System.Net.WebClient())
{
client.Headers.Add("Accept", "application/json");
client.Headers.Add("Content-Type", "application/json; charset=utf-8");
client.DownloadString(...);
}

try to use HttpClientFactory
services.AddSingleton<WebRequestXXX>()
.AddHttpClient<WebRequestXXX>("ClientX", config =>
{
config.BaseAddress = new System.Uri("https://jsonplaceholder.typicode.com");
config.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
config.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");
});
======================
public class WebRequestXXXX
{
private readonly IHttpClientFactory _httpClientFactory;
public WebRequestXXXX(IHttpClientFactory httpClientFactory)
{
_httpClientFactory = httpClientFactory;
}
public List<Posts> GetAllPosts()
{
using (var _client = _httpClientFactory.CreateClient("ClientX"))
{
var response = _client.GetAsync("/posts").Result;
if (response.IsSuccessStatusCode)
{
var itemString = response.Content.ReadAsStringAsync().Result;
var itemJson = System.Text.Json.JsonSerializer.Deserialize<List<Posts>>(itemString,
new System.Text.Json.JsonSerializerOptions
{
PropertyNameCaseInsensitive = true
});
return itemJson;
}
else
{
return new List<Posts>();
}
}
}
}

I got the answer whith RestSharp:
private async Task<string> GetAccessTokenAsync()
{
var client = new RestClient(_baseURL);
var request = new RestRequest("auth/v1/login", Method.POST, DataFormat.Json);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("x-api-key", _apiKey);
request.AddHeader("Accept-Language", "br");
request.AddHeader("x-client-tenant", "1");
...
}
It worked for me.

You need to do it like this:
HttpContent httpContent = new StringContent(#"{ the json string }");
httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage message = client.PostAsync(#"{url}", httpContent).Result;

For those wanting to set the Content-Type to Json specifically, you can use the extension method PostAsJsonAsync.
using System.Net.Http.Json; //this is needed for PostAsJsonAsync to work
//....
HttpClient client = new HttpClient();
HttpResponseMessage response = await
client.PostAsJsonAsync("http://example.com/" + "relativeAddress",
new
{
name = "John Doe",
age = 33
});
//Do what you need to do with your response
The advantage here is cleaner code and you get to avoid stringified json. More details can be found at: https://learn.microsoft.com/en-us/previous-versions/aspnet/hh944339(v=vs.118)

I find it most simple and easy to understand in the following way:
async Task SendPostRequest()
{
HttpClient client = new HttpClient();
var requestContent = new StringContent(<content>);
requestContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
var response = await client.PostAsync(<url>, requestContent);
var responseString = await response.Content.ReadAsStringAsync();
}
...
SendPostRequest().Wait();

I end up having similar issue.
So I discovered that the Software PostMan can generate code when clicking the "Code" button at upper/left corner. From that we can see what going on "under the hood" and the HTTP call is generated in many code language; curl command, C# RestShart, java, nodeJs, ...
That helped me a lot and instead of using .Net base HttpClient I ended up using RestSharp nuget package.
Hope that can help someone else!

Api returned
"Unsupported Media Type","status":415
Adding ContentType to the jsonstring did the magic and this is my script working 100% as of today
using (var client = new HttpClient())
{
var endpoint = "api/endpoint;
var userName = "xxxxxxxxxx";
var passwd = "xxxxxxxxxx";
var content = new StringContent(jsonString, Encoding.UTF8, "application/json");
var authToken = Encoding.ASCII.GetBytes($"{userName}:{passwd}");
client.BaseAddress = new Uri("https://example.com/");
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(authToken));
HttpResponseMessage response = await client.PostAsync(endpoint, content);
if (response.IsSuccessStatusCode)
{
// Get the URI of the created resource.
Uri returnUrl = response.Headers.Location;
Console.WriteLine(returnUrl);
}
string responseBody = await response.Content.ReadAsStringAsync();
return responseBody;
}

For my scenario, a third-party API was creating the HttpRequestMessage, so I was not able to use the top-voted answers to resolve the issue. And I didn't like the idea of messing with reflection so the other answers didn't work either.
Instead, I extended from AndroidMessageHandler and used this new class as a parameter to HttpClient. AndroidMessageHandler contains the method SendAsync which can be overridden in order to make changes to the HttpRequestMessage object before it is sent. If you don't have access to the Android Xamarin libaries, you may be able to figure something out with HttpMessageHandler.
public class XamarinHttpMessageHandler : global::Xamarin.Android.Net.AndroidMessageHandler
{
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
// Here I make check that I'm only modifying a specific request
// and not all of them.
if (request.RequestUri != null && request.RequestUri.AbsolutePath.EndsWith("download") && request.Content != null)
{
request.Content.Headers.Add("Content-Type", "text/plain");
}
return base.SendAsync(request, cancellationToken);
}
}
Then to use:
var client = new HttpClient(new XamarinHttpMessageHandler());

So if you're trying to do a /$batch OData request like this Microsoft article demonstrates where you're supposed to have a Content-Type header like:
Content-Type: multipart/mixed;boundary=batch_d3bcb804-ee77-4921-9a45-761f98d32029
string headerValue = "multipart/mixed;boundary=batch_d3bcb804-ee77-4921-9a45-761f98d32029";
//You need to set it like thus:
request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse(headerValue);
Again, the magic you need is: MediaTypeHeaderValue.Parse(...)

stringContent.Headers.ContentType = new MediaTypeHeaderValue(contentType);
And 🎉 YES! 🎉 ... that cleared up the problem with ATS REST API: SharedKey works now! 😄 👍 🍻
Source: https://github.com/dotnet/runtime/issues/17036#issuecomment-212046628

.NETCore HttpWebRequest - Old Way isn't Working

Before I upgraded to the newest .NetCore I was able to run the HttpWebRequest, add the headers and content Type and pull the stream of the JSON file from Twitch. Since the upgrade this is not working. I receive a Web Exception each time I go to get the response Stream. Nothing has changed with twitch because it still works with the old Bot. The old code is below:
private const string Url = "https://api.twitch.tv/kraken/streams/channelname";
HttpWebRequest request;
try
{
request = (HttpWebRequest)WebRequest.Create(Url);
}
request.Method = "Get";
request.Timeout = 12000;
request.ContentType = "application/vnd.twitchtv.v5+json";
request.Headers.Add("Client-ID", "ID");
try
{
using (var s = request.GetResponse().GetResponseStream())
{
if (s != null)
using (var sr = new StreamReader(s))
{
}
}
}
I have done some research and found that I may need to start using either an HttpClient or HttpRequestMessage. I have tried going about this but when adding headers content type the program halts and exits. after the first line here: (when using HttpsRequestMessage)
request.Content.Headers.ContentType.MediaType = "application/vnd.twitchtv.v5+json";
request.Content.Headers.Add("Client-ID", "rbp1au0xk85ej6wac9b8s1a1amlsi5");

You are trying to add a ContentType header, but what you really want is to add an Accept header (your request is a GET and ContentType is used only on requests which contain a body, e.g. POST or PUT).
In .NET Core you need to use HttpClient, but remember that to correctly use it you need to leverage the use of async and await.
Here it is an example:
using System.Net.Http;
using System.Net.Http.Headers;
private const string Url = "https://api.twitch.tv/kraken/streams/channelname";
public static async Task<string> GetResponseFromTwitch()
{
using(var client = new HttpClient())
{
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/vnd.twitchtv.v5+json"));
client.DefaultRequestHeaders.Add("Client-ID", "MyId");
using(var response = await client.GetAsync(Url))
{
response.EnsureSuccessStatusCode();
return await response.Content.ReadAsStringAsync(); // here we return the json response, you may parse it
}
}
}

Strange HttpClient result

When trying to get data from a Hitbox API I get a strange result. For a one API's command it happens everytime, for the other only sometimes. The result more or less like that (this is the last result I have got):
\u001f�\b\0\0\0\0\0\0\u0003콋w�8������s�Μmu�~��s��N�t&��N�g6��C��Ͷ$z%9igf��[(�\u0005�\u000f��(:�6����\u000f\b P�C\u0015\n�\u007f�V�\u007f�d��h����2_�&��Nj,�����S������q�\u0017�7��\u0019<�n�~��YoVY�\u0018M>�S�kP���|^���w������9�w2��\u0605�4�Ƿ�&\u0015�ƛ��Xo�\u0014[�6w\u0011onVP\u0005��e\u000e��\u05ca�l�/����⇝��%�u�u�s�����=���k�w��z\u0003�a����SR,���s�1����ůdž��2~.6\u0006T>��fR��l�(���\u0017�GHoV�&/�m#�'\u0013�C�N/��E|Q�\u0012���3+�6\u0003z\u0012���q>�{�_��eW�7\u0016�rsIw\u0012\u0018&\u0017��V�\u000f�Ŀ\u001f������e�\u0002A��Zg��U\u0006��\\g\u0015�VP��u.E8Hj�LA���/͋��|�����;xk\u001e��ǣZ�\3y��\u00019\u0017���ī\u0002��ڜ���u����O]v���XA�{�\u0004�K�l.o\u0016�%t\u0006�<{̆O��=�\u0017\u0017\u0015%$G��\"Oϡ�\u007f����^̹hH���q�8�\u0001�6�\u0015�y�{��S��4+�pb-\\eI�bB]^\u001f��{��jՊx�\u0004��\u0001�º��QD��\u001eK\u0001;�\u0002+��Y���!�\a��\u001a��(()>e��ש�r0T?��\u001f�Q���5t�R���� \u0005\u001f(���l\u0013�\v�\r-�\n�U?߭_��&�l>�\r0(N4))/���uc��3�\<�U\u0013\u001f\u0002ȱ���^n6ד��g�/�ʹ��ͧ��rP����\u001f���\f4y~\u0005=�V3�\u001c;�k\u0002}�'�m\u001cc�oG��_\u0003b�4�`��
It's much much longer but it's pointless to copy all of it (about 30000 characters).
My code that I use to get the json result is:
string result;
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(hitboxApiLink);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = client.GetAsync(requestString).Result;
result = response.Content.ReadAsStringAsync().Result;
}
return result;
I used this before:
HttpWebRequest request = (HttpWebRequest) WebRequest.Create(Path.Combine(hitboxApiLink, requestString));
request.KeepAlive = false;
request.ContentType = "application/json; charset=utf-8";
WebResponse response = request.GetResponse();
using(StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
{
result = reader.ReadToEnd();
}
And it returns the same. But when I try to get data with Google Chrome or Internet Explorer it returns normal result. The api is: http://developers.hitbox.tv/
The link I try to get data from is: https://api.hitbox.tv/media/live/list

The response is GZIPped (even though this wasn't specified by an Accept-Encoding header in the request, so is technically a fault on the server).
Your second example can be fixed by adding the following line before you fire off the request:
request.AutomaticDecompression = DecompressionMethods.GZip;
This should give you everything you need to figure out how to decompress the response of the HttpClient version.