How to upload TextFile from Windows forms to a specific Url with WebClient?

Question

I want to send a normal text file from my VisualStudio C# Windows Forms Application via "Post" to an Url with a WebClient. my code:

using(WebClient w = new WebClient())
{
   w.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
   string HtmlResult = w.UploadString(@"http://xxx/api/test", "Post", @"C:\Temp\T.txt");
}

This is what I found so far. When I run this code the post method in my web project gets hit but the param is null (which is understandable since its data type is a string but it is also null when I change the file address to a simple string like "test").

So my real problem is that I can´t send my text data to my URL.

Answer 1

First, your ContentType should be "application/text" not "application/x-www-form-urlencoded".

Second, this method defaults to POST for HTTP/HTTPS so use the overload that takes two string parameters UploadString("destination Url", "data"). If you just must use the three parameter overload, the method should be "POST" not "Post".

This method does not read the file for you, you will need to add code to read the contents of your file into a string, then pass that string to the data parameter of the UploadString method.

I probably should add that, in the recieving api you will read the data from the Request.InputStream object. As with any stream you will read it into a byte array and need to encode it back to a string. You must use the same encoding that was used to read the file into a string.

The stream InputStream is a one-way readonly stream, so you will need to read it in it's entirety into a byte array before encoding back to a string.