Question

I have a requirement where I have to download a zip file using c# (size can vary between 10mb – 400mb) from server based on input params. For example, download reports for userId = 10 and year = 2012.
The webserver accepts these two params and returns a zip file. How can I achieve this using WebClient class?
Thanks

Answer 1

You can do so by extending the WebClient class

class ExtWebClient : WebClient
    {

        public NameValueCollection PostParam { get; set; }

        protected override WebRequest GetWebRequest(Uri address)
        {
            WebRequest tmprequest = base.GetWebRequest(address);

            HttpWebRequest request = tmprequest as HttpWebRequest;

            if (request != null && PostParam != null && PostParam.Count > 0)
            {
                StringBuilder postBuilder = new StringBuilder();
                request.Method = "POST";
                //build the post string

                for (int i = 0; i < PostParam.Count; i++)
                {
                    postBuilder.AppendFormat("{0}={1}", Uri.EscapeDataString(PostParam.GetKey(i)),
                                             Uri.EscapeDataString(PostParam.Get(i)));
                    if (i < PostParam.Count - 1)
                    {
                        postBuilder.Append("&");
                    }
                }
                byte[] postBytes = Encoding.ASCII.GetBytes(postBuilder.ToString());
                request.ContentLength = postBytes.Length;
                request.ContentType = "application/x-www-form-urlencoded";

                var stream = request.GetRequestStream();
                stream.Write(postBytes, 0, postBytes.Length);
                stream.Close();
                stream.Dispose();

            }

            return tmprequest;
        }
    }

Usage : in case u have to create POST type request

class Program
{
    private static void Main()
    {
        ExtWebClient webclient = new ExtWebClient();
        webclient.PostParam = new NameValueCollection();
        webclient.PostParam["param1"] = "value1";
        webclient.PostParam["param2"] = "value2";

        webclient.DownloadFile("http://www.example.com/myfile.zip", @"C:\myfile.zip");
    }
}

Usage : for GET type request, u can simply use the Normal webclient

class Program
{
    private static void Main()
    {
        WebClient webclient = new WebClient();

        webclient.DownloadFile("http://www.example.com/myfile.zip?param1=value1&param2=value2", @"C:\myfile.zip");
    }
}