Saturday, February 21, 2015

Using Javascript RegExp Object to replace a XPages Contraint Validator

I had an occasion yesterday where I needed change a partial refresh to process data without validation in order to fix another problem. Despite this I still needed to validate the data the user enters based on a regular expression.  The previous developer was was using a <xp:validateContraint> to check the data, but this check would no longer trigger since I am skipping validation. The constraint validator uses a regular expression to determine whether the validation passes or not.

Even though the regular expression in this case was simplistic, I did not want to mirror what it does using string manipulation to validate it. 
I remembered from one of my Javascript books (Professional JavaScript for Web Developers) that Regular Expressions are built into the language.  It was very easy to duplicate the constraint functionality by just copying the RegExp string that already worked and then creating a RegExp javascript object.   

The code here lives in a button in the SSJS onclick event: 

var thisID = getComponent("inputID").getValue(); 
var pattern = /^([A-Za-z]{2}[A-Za-z0-9]{0,2})$/; 
     return viewScope.infoMessage = "No Can Do";

The built-in RegExp object can be created in one of two ways, you can either use the slash as I do in the above code or you can create it using new RegExp("....").  Either way that you choose, it works the same. The object has a method called test() which will return a true/false depending if the passed in string matches.  Of course, you can use this in any javascript, client or serverside.