Lee Kelleher

How to convert NameValueCollection to a (Query) String

Posted on . Estimated read time: under a minute (132 words)

Most ASP.NET developers know that you can get a key/value pair string from the Request.QueryString object (via the .ToString() method). However that functionality isn't the same for a generic NameValueCollection object (of which Request.QueryString is derived from).

So how do you take a NameValueCollection object and get a nicely formatted key/value pair string? (i.e. "key1=value1&key2=value2") ... Here's a method I wrote a while ago:

/// <summary>
/// Constructs a QueryString (string).
/// Consider this method to be the opposite of "System.Web.HttpUtility.ParseQueryString"
/// </summary>
public static string ConstructQueryString(NameValueCollection parameters)
	List<string> items = new List<string>();

	foreach (string name in parameters)
		items.Add(string.Concat(name, "=", System.Web.HttpUtility.UrlEncode(parameters[name])));

	return string.Join("&", items.ToArray());

Just in case you didn't know about the System.Web.HttpUtility.ParseQueryString method, it's a quick way of converting a query (key/value pairs) string back into a NameValueCollection.