WebClient set headers

c# .net header webclient
The Mask picture The Mask · Jul 3, 2011 · Viewed 79k times · Source

How I can set a header in the webClient class? I tried:

client.Headers["Content-Type"] = "image/jpeg";

that throws a WebException

My code:

WebClient client = new WebClient();
client.Headers.Set("Content-Type", "image/png");
client.Headers.Set("Content-Length", length);
client.Headers.Add("Slug", name);
NameValueCollection nvc = new NameValueCollection();
nvc.Add("file", FileContents);

Byte[] data = client.UploadValues(url, nvc);
string res = Encoding.ASCII.GetString(data);
Response.Write(res);

Answer

jdc0589 picture jdc0589 · Jul 3, 2011

If the header already exists:

client.Headers.Set("Content-Type", "image/jpeg");

if its a new header:

client.Headers.Add("Content-Type", "image/jpeg");

Also, there is a chance that you are getting an error because you are trying to set the headers too late. Post your exception so we can let you know.

Update

Looks like there are some weird restrictions on the "Content-Type" header with the WebClient class. Look in to using the client.Download methods (DownloadData, DownloadFile, etc...)

See if using the "UploadFile" method on webclient works rather than doing it manually. It returns the respose body byte[].

If you continue to have issues with the WebClient, try justing using a plain old HttpRequest/HttpWebRequest.

Related questions

How to make an HTTP POST web request

Canonical How can I make an HTTP request and send some data using the POST method? I can do a GET request, but I have no idea of how to make a POST request.

Read More
How can I convert String to Int?

I have a TextBoxD1.Text and I want to convert it to an int to store it in a database. How can I do this?

Read More
What is a NullReferenceException, and how do I fix it?

I have some code and when it executes, it throws a NullReferenceException, saying: Object reference not set to an instance of an object. What does this mean, and what can I do to fix this error?

Read More