[Tip of the Week] Using Inheritence to Share Event Handler Code

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1

In ColdBox, controllers or event handlers as we call them are defined as CFCs. Part of the power of this is that you can share and extend code in your applications by simply extending one handler with another.

Imagine a reporting framework where a number of reports will all have a criteria page, validation, execution, and export data action with most of the logic, views, layouts, and models the same between every report while still allowing for customizations on a per-report basis.

You could set up a base report handler that contained shared stuff like so:

component name=“BaseReport” extends=“coldbox.system.eventhandler” output=“false”
{
property name=“ReportService” inject;

public function init(Controller){
super.init(arguments.controller);
return this;
}

function criteria(Event, rc, prc){
// Common Code
}

function execute(Event, rc, prc){
// Common Code
}

function showResults(Event, rc, prc){
// Common Code
}

}

And then extend it per report with concrete handlers that add their own customizations:

component name=“MyReport” extends=“BaseReport” output=“false”
{
property name=“myReportDAO” inject;

function criteria(Event, rc, prc){
super.criteria(Event, rc, prc);
// Add in custom goodness for this report.
}
}

More info on how amazing handlers are here: http://wiki.coldbox.org/wiki/EventHandlers.cfm

P.S. Remember, since ColdBox is chock full of choices, your event handlers don’t have to eventually extend coldbox.system.eventhandler. We could leave off the extends and the super.init() call on our BaseReport and WireBox will use virtual inheritance to ensure the handler has everything it needs.

Thanks!

~Brad

ColdBox Platform Evangelist
Ortus Solutions, Corp

E-mail: brad@coldbox.org
ColdBox Platform: http://www.coldbox.org
Blog: http://www.codersrevolution.com