PRB: Active Server Pages' Request.Form and Request.QueryString Return Objects

MORE INFORMATION

The following call evaluates to TRUE:

   <% IsObject(Request.Form("Valid_Form_Value")) %>
				

This is because the Request object returns an IRequestDictionary object rather than a string. In most cases, this subtle fact goes unnoticed because the scripting engine simply substitutes the default value of the object into scripts as necessary. The following example demonstrates what happens when you assign the requested value to a variable:

   <% MyValue = Request.QueryString("Valid_QueryString_Value") %>
				

However, this subtlety causes problems in some scenarios. In particular, it may be necessary to perform explicit casts in JScript or when calling automation methods on objects.

Another option is to use the .item syntax to extract the default value of the object. The following IsObject call evaluates to FALSE and demonstrates use of the .item syntax:

   <% IsObject (Request.QueryString("Valid_Form_Value").item) %>