[[TOC(heading=Training Section Contents, Training*)]]

= Section 5: Mother's Little Helper =

Part of a quality design is in not repeating the prescription of algorithms. Sure we can encapsulate our algorithm in a User Defined Function (UDF), but in a Model-Glue world, where do UDFs go?

Model-Glue 3 introduces the concept of helpers. Helpers are libraries of user defined functions. By placing these files in the proper location, Model-Glue 3 will automatically load them and make them accessible via the new helpers scope, available to both controller and view files. Let's implement a helper in our application.

 1. Open /PlantOMatic/config/ColdSpring.xml, find the definition for modelglue.modelGlueConfiguration and ensure you have a helper mapping pointing to /PlantOMatic/helpers:

{{{

<property name="helperMappings"><value>/PlantOMatic/helpers</value></property>

}}}

 2. Create a new file called date.cfm inside /PlantOMatic/helpers 
 3. Place the following function inside /PlantOMatic/helpers/date.cfm 

{{{

<cfscript>
/*
* Calculates the number of business days between 2 dates.
* @param date1 First date. (Required)
* @param date2 Second date. (Required)
* @return Returns a number.
* @author Harry Goldman (harry@icn.net)
* @version 1, April 10, 2008
*/

function businessDaysBetween( date1, date2 ) {
    var numberOfDays = 0;
    
    while ( date1 LT date2 ) {
        date1 = dateAdd( "d", 1, date1 );
        if ( dayOfWeek( date1 ) GTE 2 AND dayOfWeek( date1 ) LTE 6 )
            numberOfDays = incrementValue( numberOfDays );
    }
    return numberOfDays;
}
</cfscript>

}}}

 4. Open the file /PlantOMatic/views/List.Shipment.cfm and change the following line:

{{{

<td>#dateFormat( CreateDate, "short" )#</td>

}}}

 To call our new UDF from the helpers scope:

{{{

<td>#dateFormat( CreateDate, "short" )#  (#helpers.date.businessDaysBetween( CreateDate, now() )# Business days ago)</td>

}}}


 5. Now, click the Home navigation element again to run the Saved Shipments screen and see the new helper in action:

[[Image(training05-1.png, nolink)]][[BR]]
'' Date displayed with helper function ''

Helpers are a helpful (''editor's note: remove lame pun'') way to organize your User Defined Functions and share them across views and controllers. For more information on Model-Glue Helpers, visit the following documentation:


[http://docs.model-glue.com/wiki/HowTos/HowToUseHelpers How To Use Helpers]

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