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How to replicate Postman POST request in C#

I'm fairly new to .NET's HTTPClient class, hence kindly excuse if I sounded noob. I'm tryin to replicate Postman's POST request in C# .Net and written following code. However I'm not getting any response but StatusCode: 404. Could someone assist understanding where I'm going wrong?
Also I'd like to understand, how do set Body in following code.
var httpClient = new HttpClient
{
BaseAddress = new Uri("https://testURL.com"),
Timeout = TimeSpan.FromMinutes(10)
};
httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("audio/wav"));
httpClient.DefaultRequestHeaders.Add("Authorization", "Basic ldjfdljfdlfjdsjfdsl");
var content = new FormUrlEncodedContent(new[]
{
new KeyValuePair<string, string>("model", "Test"),
});
var result = httpClient.PostAsync("api/v1/recognize", content).Result;
Here is what I'm doing in Postman and it works:

"Params" in Postman refers to query parameters which are appended to the URL. You'll see that the URL in Postman contains the parameters you added in the "Params" tab:
However, it seems those are just dummy values you've entered so perhaps you don't need them? In any case, the way you add query parameters to the request for HttpClient is a little different as it needs to be added to the URL.
After that you also need to add the audio file as content to your request. At the moment you're setting the "Accept" header to "audio/wav" but you probably want to set the "Content-Type" header instead (or are you expecting a WAV file to be returned in the response too?).
As far as I can see this is what you're missing:
using (var httpClient = new HttpClient())
{
httpClient.Timeout = TimeSpan.FromMinutes(10);
// Set request headers
httpClient.DefaultRequestHeaders.Add("Authorization", "Basic ldjfdljfdlfjdsjfdsl");
// Set query parameters
var uriBuilder = new UriBuilder("https://testURL.com/api/v1/recognize");
uriBuilder.Query = "model=Test";
// Build request body
// Read bytes from the file being uploaded
var fileBytes = File.ReadAllBytes(wavFilePath);
// Create request content with metadata/headers to tell the
// backend which type of data (media type) is being uploaded
var byteArrayContent = new ByteArrayContent(fileBytes);
byteArrayContent.Headers.ContentType = MediaTypeHeaderValue.Parse("audio/wav");
// Wrap/encode the content as "multipart/form-data"
// See example of how the output/request looks here:
// https://dotnetfiddle.net/qDMwFh
var requestContent = new MultipartFormDataContent
{
{byteArrayContent, "audio", "filename.wav"}
};
var response = await httpClient.PostAsync(uriBuilder.Uri, requestContent);
}
I haven't tested this of course against your application, but it should be something along the lines of this. It might be that the backend doesn't expect "multipart/form-data" and just needs the "audio/wav". I can't see the output headers in your Postman screenshots, but if so, you can use byteArrayContent directly instead of wrapping it in MultipartFormDataContent.
Note: Don't use httpClient.PostAsync(...).Result. If you want to use the asynchronous method, you should await it. Depending on your code, using Result might give you problems if you're not careful. And remember to dispose the HttpClient after use (easiest solution is to use a using statement). If you plan on reusing the HttpClient for more requests, you can avoid disposing it until you're done.

How to add the header Xamarin Forms using System.Net.Http; [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

Send file attachment to Facebook messenger API in C#

I looked at the messenger documentation at https://developers.facebook.com/docs/messenger-platform/send-messages/#file to try and figure out how to send local attachments. However, when I try it out with a httpclient I get an error saying that the message body can not be empty must provide a valid attachment or message. Below is my code
string fileType = ImageExtensions.Contains(Path.GetExtension(url).ToUpper()) ? "image" : "file";
var multipartContent = new MultipartFormDataContent();
var content = new StringContent($"{{\"attachment\":{{\"type\":\"{fileType}\", \"payload\":{{\"is_reusable\"=true}}}}");
multipartContent.Add(new StringContent($"{{\"id\":\"{long.Parse(recipient)}\"}}"), "recipient");
multipartContent.Add(new StringContent($"{{\"attachment\":{{\"type\":\"{fileType}\", \"payload\":{{\"is_reusable\"=true}}}}"), "message");
var file1 = File.ReadAllBytes(url);
var file2 = new ByteArrayContent(file1);
file2.Headers.Add("Content-Type", GetMimeType(Path.GetExtension(url)));
multipartContent.Add(file2,"filedata", Path.GetFileName(url));
request.Content = multipartContent;
The file type is image and the mime type is image/jpeg. I know the url exists as I checked File.exists

Welcome to Stack Overflow!
From the code sample provided it's quite hard to work out what's going wrong as it's not runnable in isolation.
That said, I'd first verify that the image you're consuming by url exists in the format you expect. If you download the .jpeg from the url can you open it on your machine? Assuming it's well structured I'd then try and work out if it's the HttpClient that's malformed - or if there's something wrong with the values you're providing to the Facebook API.
You can do this by creating a simple C# Web API project that listens for a multipart upload on a specific route. See this answer for some sample code on how to do this.
Assuming that you're able to send the .jpeg in question between a local client and a local endpoint accepting a multipart/form-data header then the issue must be with how you're using the Facebook API itself.
In your sample I don't see you using the value of the content variable anywhere. Is this intentional?
If that missing variable is a red-herring then you could try running something along the lines of (making sure to swap the values out as necessary for the ones you're having problems with):
using (var httpClient = new HttpClient())
using (var formDataContent = new MultipartFormDataContent())
{
// Read the file in from a local path first to verify that the image
// exists in the format you're expecting.
var fileStream = File.OpenRead("/some/path/image.jpeg");
using (var streamContent = new StreamContent(fileStream))
{
// Don't actually call `.Result` you should await this, but for ease of
// demonstration.
var imageContent = new ByteArrayContent(streamContent.ReadAsByteArrayAsync().Result);
imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");
formDataContent.Add(imageContent, "image", "your-file-name-here");
formDataContent.Add(new StringContent ($"{{\"id\":\"{long.Parse("your-recipient-here")}\"}}"), "recipient");
formDataContent.Add(new StringContent($"{{\"attachment\":{{\"type\":\"{"image"}\", \"payload\":{{\"is_reusable\"=true}}}}"), "message");
// Again don't call `.Result` - await it.
var response = httpClient.PostAsync("https://some-url-here.com", formDataContent).Result;
}
}
If you run the above do you still get an empty message body error?

If you stumble upon this and you're using the FacebookClient from Nuget. This is how I finally managed to upload files to the messages api using vb.net.
Dim Client = New FacebookClient(GetPageAccessToken(PageID))
Dim TmpParams As New Dictionary(Of String, Object)
TmpParams.Add("recipient", "{""id"":""RECIPIENT_ID""}")
TmpParams.Add("message", "{""attachment"":{""type"":""image"", ""payload"":{""url"":"""", ""is_reusable"":false}}}")
TmpParams.Add("messaging_type", "RESPONSE")
Dim Med As New FacebookMediaObject()
Med.FileName = YourFile.FileName
Med.ContentType = YourFile.ContentType
Med.SetValue(YourFile.InputStream.ToBytes())
TmpParams.Add(YourFile.FileName, Med)
Client.Post("me/messages", TmpParams)
Using a Dictionary(of string,object), manually add the params for recipient,message,messaging_type and the file bytes.

Rest calls in c#

I am struggling with Rest call. Here is my code and it is working for basic authentication.
public async Task RunAsync(string name, string value)
{
using (var handler = new HttpClientHandler { UseDefaultCredentials = true })
using (var client = new HttpClient(handler))
{
var byteArray = Encoding.ASCII.GetBytes("username:password");
client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
var urlRestGet = HomeController.url;
client.BaseAddress = new Uri(urlRestGet + "?name=" + name + "&value=" + value + "");
client.DefaultRequestHeaders.Accept.Clear();
**1. if(HomeController.contentType.ToLower()=="xml"){
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/xml"));
}**
else if (HomeController.contentType.ToLower() == "json")
{
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
}
HttpResponseMessage response = await client.GetAsync(urlRestGet + "?name=" + name + "&value=" + value + "");
if (response.IsSuccessStatusCode)
{
//Get the response
loginJsonString = await response.Content.ReadAsStringAsync();
//Converting to xml
using (var stream = new MemoryStream(Encoding.ASCII.GetBytes(loginJsonString)))
{
var output = new XmlDictionaryReaderQuotas();
xmlResult = XDocument.Load(JsonReaderWriterFactory.CreateJsonReader(stream, output)).ToString();
}
}
}
}
1) If the content type is application/xml am I correct to use line 1 part in the code.
2) How can I make this code more generic. (when the authentication type is different eg: tokenized or cookiebased how can I change this.)

There are a couple of things about your code I do not understand.
What is HomeController.contentType all about? The name "HomeController" suggests you're writing an ASP.NET MVC Controller (serverside). Though you seem to be writing something intended to be used as a HTTP client. But I could be mistaken or mislead here.
You are reading a Json response, then loading it as a Xml document?
I'll try to answer anyway.
1) If the content type is application/xml am I correct to use line 1 part in the code.
The Accept header sent by the client (you) tells the server that you accept the given content type. If you send Accept application/xml you tell the server you prefer if the response is Xml.
Your code seem to assume the response's content type is always Json.
You could include both application/xml and application/json as Accept headers in your request. The server should honor that request and pick the first supported content type for it's response.
When processing the response you should check the actual content type and handle the response content appropriately.
Remember that Accept only tells the server that you prefer those content types. The server may decide not to honor your whishes and can return any content type it desires.
2) How can I make this code more generic. (when the authentication type is different eg: tokenized or cookiebased how can I change this.)
If you mean tokenized as in a query parameter you should probably handle your query parameters as a collection rather than a hardcoded formatted string.
Check out the NameValueCollection class and this SO question on NameValueCollection to query string.
To handle cookies, you basically need to copy/re-use the cookie collection returned in a response in the next request.
See this SO question on how to inject cookies when you create a new HttpClient.
... but it's much easier to use a library
As you already discovered, making a robust REST/HTTP client is not a easy task.
And as #Mafii and #Fildor already pointed out in comments there are already numerous libraries available. RestSharp (https://restsharp.org) being one very popular.

How to send a pushover notification with attached image in C# .NET

I'm trying to send a push notification though Pushover API with attached image using C# .NET. The following code returns a json formatted error "message cannot be blank". But the message variable is not empty. Since SSL is outdated I tried using TLS 1.2 explicitly. The same error appears without the image parameter.
public async Task PushImage(string title, string message, Stream image, string userKey, string appKey)
{
// This does not work - error "message cannot be blank"
using (HttpClient httpClient = new HttpClient())
{
//specify to use TLS 1.2 as default connection
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
MultipartFormDataContent form = new MultipartFormDataContent();
form.Add(new StringContent(appKey), "token");
form.Add(new StringContent(userKey), "user");
form.Add(new StringContent(message), "message");
var imageParameter = new StreamContent(image);
imageParameter.Headers.ContentType = MediaTypeHeaderValue.Parse("image/png");
form.Add(imageParameter, "attachment", "image.png");
// Remove content type that is not in the docs
foreach (var param in form)
param.Headers.ContentType = null;
HttpResponseMessage responseMessage = await httpClient.PostAsync(BaseApiUrl, form);
if (responseMessage.IsSuccessStatusCode)
return;
string contentText = responseMessage.Content.ReadAsStringAsync().Result;
var response = JsonConvert.DeserializeObject<PushResponse>(contentText);
throw new ApplicationException(
$"Push image request failed with status {(int)responseMessage.StatusCode} {responseMessage.StatusCode}: {response.Errors.JoinStrings(". ") ?? ""}");
}
}
Result:
{"message":"cannot be blank","errors":["message cannot be blank"],"status":0,"request":"94152901-3b8f-45d6-ae6b-f7fc10b3439c"}
I've looked at the raw request through Charles and it appears more or less as the docs suggest. However there is a small difference.
Curl - which works - produces parameters that look like this:
--------------------------30e0433d33c92cae
Content-Disposition: form-data; name="message"
my message
--------------------------30e0433d33c92cae--
HttpClient - which does not yet work - produces this for each parameter:
--70ae375f-ef30-4885-8a8a-d38363080024
Content-Disposition: form-data; name=message
my message
--70ae375f-ef30-4885-8a8a-d38363080024--
Note the difference in quotes. If I intercept the message in Charles and enclose the parameter names in double quotes as well as increase Content-Length by the same amount, it works!

It turns out that you need to enclose the parameter names in double quotes, like so:
form.Add(new StringContent(appKey), "\"token\"");
form.Add(new StringContent(userKey), "\"user\"");
form.Add(new StringContent(message), "\"message\"");
...
form.Add(imageParameter, "\"attachment\"", "image.png");
Don't ask me why. I just want to get on with my life and forget this entire day I spent debugging this issue...