HttpClient: The uri string is too long

Question

Given the following attempt to post data to a web service that generates PDF files, PDF rocket (which is awesome by the way).

I get the error Invalid URI: The uri string is too long
Why would anyone impose an arbitrary limit on POSTed data?

using (var client = new HttpClient())
{
    // Build the conversion options
    var options = new Dictionary<string, string>
    {
        { "value", html },
        { "apikey", ConfigurationManager.AppSettings["pdf:key"] },
        { "MarginLeft", "10" },
        { "MarginRight", "10" }
    };

    // THIS LINE RAISES THE EXCEPTION
    var content = new FormUrlEncodedContent(options);

    var response = await client.PostAsync("https://api.html2pdfrocket.com/pdf", content);
    var result = await response.Content.ReadAsByteArrayAsync();
    return result;
}

I receive this rediculous error.

 {System.UriFormatException: Invalid URI: The Uri string is too long.
   at System.UriHelper.EscapeString
   at System.Uri.EscapeDataString
   at System.Net.Http.FormUrlEncodedContent.Encode
   at System.Net.Http.FormUrlEncodedContent.GetContentByteArray

This reminds me of 640k ought to be enough... I mean really?

Answer 1

If, like me, you're faced with some wonky 3rd party web service that will only accept form content, you can work around the problem like this:

// Let's assume you've got your key-value pairs organised into a nice Dictionary<string, string> called formData
var encodedItems = formData.Select(i => WebUtility.UrlEncode(i.Key) + "=" + WebUtility.UrlEncode(i.Value));
var encodedContent = new StringContent(String.Join("&", encodedItems), null, "application/x-www-form-urlencoded");

// Post away!
var response = await client.PostAsync(url, encodedContent);