HttpClient: The uri string is too long

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);