Check if unassigned variable exists in Request.QueryString

Question

Within the context of an ASP.NET page, I can use Request.QueryString to get a collection of the key/value pairs in the query string portion of the URI.

For example, if I

Answer 1

I wrote an extension method to solve this task:

public static bool ContainsKey(this NameValueCollection collection, string key)
{
    if (collection.AllKeys.Contains(key)) 
        return true;

     // ReSharper disable once AssignNullToNotNullAttribute
    var keysWithoutValues = collection.GetValues(null);
    return keysWithoutValues != null && keysWithoutValues.Contains(key);
}