Replace item in querystring

Question

I have a URL that also might have a query string part, the query string might be empty or have multiple items.

I want to replace one of the items in the query string

Answer 1

   public class QueryParams : Dictionary
   {
       private Uri originolUrl;
       private Uri ammendedUrl;
       private string schemeName;
       private string hostname;
       private string path;

       public QueryParams(Uri url)
       {
           this.originolUrl = url;
           schemeName = url.Scheme;
           hostname = url.Host;
           path = url.AbsolutePath;
           //check uri to see if it has a query
           if (url.Query.Count() > 1)
           {
               //we grab the query and strip of the question mark as we do not want it attached
               string query = url.Query.TrimStart("?".ToArray());
               //we grab each query and place them into an array
               string[] parms = query.Split("&".ToArray());
               foreach (string str in parms)
               {
                   // we split each query into two strings(key) and (value) and place into array
                   string[] param = str.Split("=".ToArray());
                   //we add the strings to this dictionary
                   this.Add(param[0], param[1]);
               }
           }
       }


       public QueryParams Set(string paramName, string value)
       {

           if(this.ContainsKey(paramName))
           {
               //if key exists change value
               this[paramName] = value;
               return (this);
           }
           else
           {
               this.Add(paramName, value);
               return this;
           }
       }
       public QueryParams Set(string paramName, int value)
       {
           if (this.ContainsKey(paramName))
           {
               //if key exists change value
               this[paramName] = value.ToString();
               return (this);
           }
           else 
           {
               this.Add(paramName, value);
               return this;
           }
       }

       public void Add(string key, int value)
       {
           //overload, adds a new keypair
           string strValue = value.ToString();
           this.Add(key, strValue);
       }

       public override string ToString()
       {
           StringBuilder queryString = new StringBuilder();

           foreach (KeyValuePair pair in this)
           {
               //we recreate the query from each keypair 
               queryString.Append(pair.Key + "=" + pair.Value + "&");
           }
           //trim the end of the query
           string modifiedQuery = queryString.ToString().TrimEnd("&".ToArray());

           if (this.Count() > 0)
           {
               UriBuilder uriBuild = new UriBuilder(schemeName, hostname);
               uriBuild.Path = path;
               uriBuild.Query = modifiedQuery;
               ammendedUrl = uriBuild.Uri;
               return ammendedUrl.AbsoluteUri;
           }
           else
           {
               return originolUrl.ToString();
           }
       }


       public Uri ToUri()
       {
          this.ToString();
          return ammendedUrl;
       }
   }
}