Best way to convert query string to dictionary in C#

Question

HttpUtility.ParseQueryString() parses query string into a NameValueCollection object, converting the latter to an IDictionary<string, string> is a matter of a simple foreach. This, however, might be unnecessary since NameValueCollection has an indexer, so it behaves pretty much like a dictionary.

Here is how I usually do it

Dictionary<string, string> parameters = HttpContext.Current.Request.QueryString.Keys.Cast<string>()
    .ToDictionary(k => k, v => HttpContext.Current.Request.QueryString[v]);

How about HttpUtility.ParseQueryString?

Just add a reference to System.Web.dll

Same as Sean, but with Linq (and a function you can copy and paste):

public static Dictionary<string, string> ParseQueryString(string queryString)
{
   var nvc = HttpUtility.ParseQueryString(queryString);
   return nvc.AllKeys.ToDictionary(k => k, k => nvc[k]);
}

Also, the question asked how to get it back into a query string:

public static string CreateQueryString(Dictionary<string, string> parameters)
{
   return string.Join("&", parameters.Select(kvp => 
      string.Format("{0}={1}", kvp.Key, HttpUtility.UrlEncode(kvp.Value))));
}

Just had to do this for a mono compatible solution

Regex.Matches(queryString, "([^?=&]+)(=([^&]*))?").Cast<Match>().ToDictionary(x => x.Groups[1].Value, x => x.Groups[3].Value)

In ASP.NET Core, use ParseQuery.

var query = HttpContext.Request.QueryString.Value;
var queryDictionary = Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery(query);