QuickBooks API - .NET/DevDefined - Execute V3 Query

V3-ExecuteQuery.cs

using DevDefined.OAuth.Consumer;
using DevDefined.OAuth.Framework;
using System.IO;
using System.Text;
using System.Net;
using Intuit.Ipp.DataService;
using Intuit.Ipp.Security;
using System.Web;

namespace IPPQbApiConsoleApp
{
    static class SampleCalls
    {
        public static string ExecuteV3Query(string consumerKey, string consumerSecret, string accessToken,  string accessTokenSecret, string realmId, string query)
        {
            string encodedQuery = System.Web.HttpUtility.UrlEncode(query);
            string uri = string.Format("https://quickbooks.api.intuit.com/v3/company/{0}/query?query={1}", realmId, encodedQuery);
            HttpWebRequest httpWebRequest = WebRequest.Create(uri) as HttpWebRequest;
            httpWebRequest.Method = "GET";
            httpWebRequest.Accept = "application/json";
            httpWebRequest.Headers.Add("Authorization", GetDevDefinedOAuthHeader(consumerKey, consumerSecret, accessToken, accessTokenSecret, httpWebRequest, null));
            HttpWebResponse httpWebResponse = httpWebRequest.GetResponse() as HttpWebResponse;
            using (Stream data = httpWebResponse.GetResponseStream())
            {
                //return XML response
                return new StreamReader(data).ReadToEnd();
            }

        }

        private static string GetDevDefinedOAuthHeader(string consumerKey, string consumerSecret, string accessToken, string accessTokenSecret, HttpWebRequest webRequest, string requestBody)
        {

            OAuthConsumerContext consumerContext = new OAuthConsumerContext
            {
                ConsumerKey = consumerKey,
                SignatureMethod = SignatureMethod.HmacSha1,
                ConsumerSecret = consumerSecret,
                UseHeaderForOAuthParameters = true
            };

            //We already have OAuth tokens, so OAuth URIs below are not used - set to example.com
            OAuthSession oSession = new OAuthSession(consumerContext, "https://www.example.com",
                                    "https://www.example.com",
                                    "https://www.example.com");

            oSession.AccessToken = new TokenBase
            {
                Token = accessToken,
                ConsumerKey = consumerKey,
                TokenSecret = accessTokenSecret
            };

            IConsumerRequest consumerRequest = oSession.Request();
            consumerRequest = ConsumerRequestExtensions.ForMethod(consumerRequest, webRequest.Method);
            if (requestBody != null)
            {
                consumerRequest = consumerRequest.Post().WithRawContentType(webRequest.ContentType).WithRawContent(System.Text.Encoding.ASCII.GetBytes(requestBody));
            }
            consumerRequest = ConsumerRequestExtensions.ForUri(consumerRequest, webRequest.RequestUri);
            consumerRequest = consumerRequest.SignWithToken();
            return consumerRequest.Context.GenerateOAuthParametersForHeader();
        }

    }
}

I am getting below error, Please check and provide solution a.s.a.p

The consumer request for consumer "{0}" has already been signed

I am facing the same issue now. Have you found a solution?

I'm facing the same issue, did you get it to work?