How do you test your Request.QueryString[] variables?

Question

I frequently make use of Request.QueryString[] variables.

In my Page_load I often do things like:

       int id = -1;          if (Request.QueryString["id"] != null) {             try             {                 id = int.Parse(Request.QueryString["id"]);             }             catch             {                 // deal with it             }         }          DoSomethingSpectacularNow(id); 

It all seems a bit clunky and rubbish. How do you deal with your Request.QueryString[]s?

Answer 1

Below is an extension method that will allow you to write code like this:

int id = request.QueryString.GetValue<int>("id"); DateTime date = request.QueryString.GetValue<DateTime>("date"); 

It makes use of TypeDescriptor to perform the conversion. Based on your needs, you could add an overload which takes a default value instead of throwing an exception:

public static T GetValue<T>(this NameValueCollection collection, string key) {     if(collection == null)     {         throw new ArgumentNullException("collection");     }      var value = collection[key];      if(value == null)     {         throw new ArgumentOutOfRangeException("key");     }      var converter = TypeDescriptor.GetConverter(typeof(T));      if(!converter.CanConvertFrom(typeof(string)))     {         throw new ArgumentException(String.Format("Cannot convert '{0}' to {1}", value, typeof(T)));     }      return (T) converter.ConvertFrom(value); }