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Working with Events

Event handlers are the controller layer in ColdBox and is what you will be executing via the URLor a FORMpost. All event handlers are singletons, which means they are cached for the duration of the application, so always remember to var scope your variables in your functions.
Tip: For development we highly encourage you to turn handler caching off or you will have to reinit the application in every request, which is annoying. Open the config/ColdBox.cfc and look for the coldbox.handlerCaching setting.  
​
By default this is already done for you on the application templates.
config/Coldbox.cfc
/**
 * Development environment
 */
function development() {
    coldbox.customErrorTemplate = "/coldbox/system/exceptions/Whoops.cfm"; // interactive bug report
    coldbox.handlerCaching = false;
    coldbox.handlersIndexAutoReload = true;
    coldbox.eventCaching = false;
    coldbox.viewCaching = false;
}
Handler Code
Go open the handlers/main.cfc and let's explore the code.
component extends="coldbox.system.EventHandler" {
​
    /**
     * Default Action
     */
    function index( event, rc, prc ) {
        prc.welcomeMessage = "Welcome to ColdBox!";
        event.setView( "main/index" );
    }
​
    /**
     * Produce some restfulf data
     */
    function data( event, rc, prc ) {
        return [
            { "id" : createUUID(), name : "Luis" },
            { "id" : createUUID(), name : "JOe" },
            { "id" : createUUID(), name : "Bob" },
            { "id" : createUUID(), name : "Darth" }
        ];
    }
​
    /**
     * Relocation example
     */
    function doSomething( event, rc, prc ) {
        relocate( "main.index" );
    }
​
    /************************************** IMPLICIT ACTIONS *********************************************/
​
    function onAppInit( event, rc, prc ) {
    }
​
    function onRequestStart( event, rc, prc ) {
    }
​
    function onRequestEnd( event, rc, prc ) {
    }
​
    function onSessionStart( event, rc, prc ) {
    }
​
    function onSessionEnd( event, rc, prc ) {
        var sessionScope     = event.getValue( "sessionReference" );
        var applicationScope = event.getValue( "applicationReference" );
    }
​
    function onException( event, rc, prc ) {
        event.setHTTPHeader( statusCode = 500 );
        // Grab Exception From private request collection, placed by ColdBox Exception Handling
        var exception = prc.exception;
        // Place exception handler below:
    }
​
}
Let's recap: Every action in ColdBox receives three arguments:
event - An object that models and is used to work with the current request, called the request context.
rc - A struct that contains both URL/FORM variables (unsafe data)
prc - A secondary struct that is private only settable from within your application (safe data)
Setting Views - Default Layout
This line event.setView( "main/index" ) in the index action told ColdBox to render a view back to the user found in views/main/index.cfm.  
ColdBox also has the concept of layouts, which are essentially reusable views that can wrap up other views or layouts.  They allow you to reuse content to render views/layouts inside a specific location in the CFML content.  By convention, ColdBox looks for a layout called layouts/Main.cfm.  This is yet another convention, the default layout.  Your application can have many layouts or non-layouts at all.
Working With Incoming Data
Now, let's open the handler we created before called handlers/hello.cfc and add some public and private variables so our views can render the variables.
function index( event, rc, prc ){
    // param an incoming variable.
    event.paramValue( "name", "nobody" );
    // set a private variable
    prc.when = dateFormat( now(), "full" );
    // set the view to render
    event.setView( "hello/index" );
}
Let's open the view now: views/hello/index.cfm and change it to this:
<cfoutput>
<p>Hello #encodeForHTML( rc.name )#, today is #prc.when#</p>
</cfoutput>
Please note that we used the ColdFusion function encodeForHTML() (https://cfdocs.org/encodeforhtml) on the public variable. Why? Because you can never trust the client and what they send, make sure you use the built-in ColdFusion encoding functions in order to avoid XSS hacks or worse on incoming public (rc) variables.
If you execute the event now: http://localhost:{port}/hello/index you will see a message of Hello nobody.
Now change the incoming URL to this: http://localhost:{port}/hello/index?name=ColdBox and you will see a message of Hello ColdBox.
Tip: Please see the layouts and views section for in-depth information.
Routing Params
Now let's expect the name as part of the URL pattern; open the config/Router.cfc and let's add another route:
route( "/hello/:name" ).as( "hello" ).to( "hello" )
We use the : colon to denote incoming URL/FORM placeholder params that, if found are translated to the request collection (rc).  So let's try it out: http://localhost:{port}/hello/coldbox
You can use the route() to generate the URL with params in a nice struct way:
<a href="#event.route( "hello", { name: "Luis" } )#">Say Hello Luis</a>
Linking Events Together
Adding A Layout
Last modified 6mo ago