C# post json object using httpWebRequst

Question

I need to post an object in this format:

POST https://link
{
 "country": "nld",
 "emailaddress": "[email protected]",
 "phone": "123",
 "notify_url": "https://asd.com"
}

I tried:

 var url = "URL";
 var httpRequest = (HttpWebRequest)WebRequest.Create(url);
 httpRequest.Accept = "*/*";
 httpRequest.Headers["Authorization"] = "Bearer " + apiKey;
 var postData = "country" + Uri.EscapeDataString("hello");
 postData += "emailaddress" + Uri.EscapeDataString("world");
 postData += "phone" + Uri.EscapeDataString("123");
 postData += "notify_url" + Uri.EscapeDataString("d3wq");
 var data = Encoding.ASCII.GetBytes(postData);
 httpRequest.Method = "POST";
 httpRequest.ContentType = "application/x-www-form-urlencoded";
 httpRequest.ContentLength = data.Length;
 using (var stream = httpRequest.GetRequestStream())
 {
 stream.Write(data, 0, data.Length);
 }
 
 HttpWebResponse httpResponse = null;
 try
 {
 httpResponse = (HttpWebResponse)httpRequest.GetResponse();
 using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
 {
 var result = streamReader.ReadToEnd();
 }
 }
 catch (Exception e) { }

But the server returns a 400 bad request. I think the data is in invalid format.

How can i alter my code to put the data into correct format ?

Thank you!

• Александр Инженер: try change to httpRequest.ContentType= "application/json"; stackoverflow.com/questions/9145667/…
• Jamshaid K.: Usually in authorization headers, a bearer access token is supplied instead of an API key.
• Self: Does this answer your question? How to post JSON to a server using C#?
• CodeCaster: @Self holy sh*t there's a lot of bad code being heavily upvoted on this site. Look at the accepted answer on the second Q&A you link to. "await Task.Run(() => JsonConvert.SerializeObject(payload))"? Really? StringContent, ReadAsStringAsync()? The PostAsJsonAsync() extension method exists for over six years already.
• Self: @CodeCaster, Good catch. I just don't read most of the code. I can find dupe target without reading the question most of the time. I will try to give answers code a better look if theirs numbers is not too big. But a basic search query return too many possible dupe.

Answer 1

The example request you show, shows a JSON request body, yet you tell the server in your HttpWebRequest that the incoming content-type is going to be a form post. But then you don't issue a form post, you post one long string:

countryhelloemailaddressworldphone123 // and so on 

Don't use HttpWebRequest in 2021. It's a two decade old API that has more developer-friendly alternatives by now.

Use HttpClient instead, which has convenient (extension) methods for sending and receiving JSON:

var postModel = new
{ 
 country = "...", 
 emailaddress = "...", 
 ... 
}; 
var client = new HttpClient();
var response = await client.PostAsJsonAsync(postModel);

You need to install the Microsoft.AspNet.WebApi.Client NuGet package for that extension method.

If you insist you must use an HttpWebRequest, which I highly doubt, your question is answered in How to post JSON to a server using C#?, as that question and answer shows how to use that ancient API.

• Jay: Than kyou. For serveral reasons, I have to use the webrequst. Can you show me how its done using this old api? :)
• Jay: is httpclient from system..net.http? cause that one doesnt have postasjsonasync for me...
• CodeCaster: See stackoverflow.com/questions/19158378/…. It's an extension method in the Microsoft.AspNet.WebApi.Client NuGet package.
• CodeCaster: Then you need to consult said API's documentation to check why it won't accept that payload.
• Jay: Thank you. Working with postman fixed the issue. Appeeantly, the API checked for the input values if they are valid e.g: is this a valid email, is this a valid phone number, etc. That was the last issue I had. Thanks for ur help!

Answer 2

Create object that you need to submit on your webrequest.

var xObject = new { xData = ... };

and after that use;

var newJsonData = JsonSerializer.Serialize(xObject);

newJsonData is a string as JSON format which you can post to your webrequest.