cannot convert from 'string' to 'System.Collections.Specialized.NameValueCollection'

Question

I am working on an asp.net mvc-4 web application , and i have the following method to upload a json object to a 3rd part application. where i want to set the url header as application/x-www-form-urlencoded :-

using (WebClient wc = new WebClient()) 
                {
                    string url = currentURL + "resources?AUTHTOKEN=" + pmtoken;
                    Uri uri = new Uri(url);

                    wc.Headers.Add(HttpRequestHeader.ContentType, "application/x-www-form-urlencoded");

                    var encodedJson = WebUtility.UrlEncode(data);
                    crudoutput = wc.UploadValues(uri, "INPUT_DATA=" + encodedJson);
                }

but the above is raising the following error :-

cannot convert from 'string' to 'System.Collections.Specialized.NameValueCollection'

The best overloaded method match for 'System.Net.WebClient.UploadValues(System.Uri, System.Collections.Specialized.NameValueCollection)' has some invalid arguments

so can anyone adivce on this please ?

Answer 1

You need to define a new NameValueCollection and pass it to UploadValues :

crudoutput = wc.UploadValues(uri, new NameValueCollection()
{
    { "INPUT_DATA", encodedJson }
});

Answer 2

WebClient UploadValues method is expecting an NameValueCollection instead of string as parameter

So you can try this :-

    using (WebClient wc = new WebClient()) 
     {
         string url = currentURL + "resources?AUTHTOKEN=" + pmtoken;
         Uri uri = new Uri(url);       
         wc.Headers.Add(HttpRequestHeader.ContentType, "application/x-www-form-urlencoded");

         var encodedJson = WebUtility.UrlEncode(data);

         NameValueCollection myNameValueCollection = new NameValueCollection();
         myNameValueCollection.Add("INPUT_DATA",encodedJson);
         crudoutput = wc.UploadValues(uri, myNameValueCollection);
     }

Answer 3

the error is pretty clear. UploadValues takes a NameValueCollection not a string https://msdn.microsoft.com/en-us/library/9w7b4fz7(v=vs.110).aspx

You code should be

var nvc = new NameValueCollection();

nvc.Add("INPUT_DATA", encodedJson);

crudoutput = wc.UploadValues(uri, nvc);

Update

You might try UploadString instead: https://msdn.microsoft.com/en-us/library/0645045y(v=vs.110).aspx

crudoutput = wc.UploadString(uri, "INPUT_DATA=" + encodedJson);