Adobe ColdFusion 8 Web Application Construction Kit, Volume 1: Getting Started

Revisiting Variables

Another important tag is <cfparam>. You won’t use this tag here, but in preparation for the next chapters, I’ll explain what this tag is and how it is used.

Earlier in this chapter, you used a function named IsDefined(), which is used to check whether a variable exists. You used IsDefined() to simply check for a variable’s existence, but what if you wanted to create a variable with a default value if it did not exist? You could do something similar to this:

<cfif NOT IsDefined("FirstName")>
 <cfset FirstName="Ben">
</cfif>

Why would you want to do this? Well, as a rule, you should not include data validation code in the middle of your core code. This is bad practice for several reasons, the most important of which are that ...