Posts Tagged ‘dry’

Roll Your Own CakePHP Components

Friday, May 22nd, 2009

As someone who is not formally trained as a programmer, I often understand concepts long before actually putting them into practice. Don’t Repeat Yourself (DRY) seems simple enough. Of course I don’t want to repeat myself while programming. Who wants to dig through lines of code to find a litte snippet of logic you once wrote? Still, when you’re pressed for time, sometimes you just have to Get Things Done (GTD). So best practices go through the window and you hammer out some spaghetti code so you can move on.

It’s only recently, since I’ve slowed down to finally understand how to write CakePHP Components, that I’ve realized that DRY enhances GTD. Now that I’ve got it all straight in my head, I’m a component evangelist.

At this point I’m going to assume that you’re familiar with MCV architecture and its benefits. Once in a while there’s a bit of logic that you find yourself coding into a controller that you realize you’re going to want to use in other controllers. It’s not specific to the model. That’s where components come in. They’re bits of logic that can be used by more than one controller. Let’s look at a simple one that converts mm/dd/yyyy dates to a Unix timestamp.

<?php
 
class DateComponent extends Object {
 
	function mkTimestamp($sentdate, $senttime){
 
		$thedate = explode('/', $sentdate);
 
		if(!empty($senttime)){
 
			$thetime = explode(':', $senttime);
			$newdate = mktime($thetime[0],$thetime[1],0,$thedate[0],$thedate[1],$thedate[2]);
 
		} else {
 
			$newdate = mktime(0,0,0,$thedate[0],$thedate[1],$thedate[2]);
 
		}
 
		return $newdate;
 
	}
 
}
?>

The function itself is not all that complicated. The thing is that I’m going to want to use this where ever I need to convert dates. Since the component is called “Date”, it’s named with the CakePHP convention for components: DateComponent. The file is called date.php and is saved in app/controllers/components.

Now we have to tell our controller(s) to use it. I’m using it across several controllers, so I’m adding it to app/app_controller.php by adding it to the $components var: var $components = array('Date');

Now I can access it in any controller like so: $tmsmp = $this->Date->mkTimestamp($thedate, $thetime);

The whole point is that components don’t have to be complex, they’re just code you want to reuse that doesn’t necessary apply to one model. They will save you time and clean up your controllers.

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Use Functions from Other Controllers While Maintaining MVC Architecture in CakePHP

Wednesday, December 10th, 2008

UPDATE (7/22/2009)

requestionAction may not be the best solution. Read this.

At my day job, I’m working on an application to keep track of specimens for our lab. A specimen is sent to the lab, then divided into aliquots which are put into boxes and stored in freezers. The previous sentence ought to give you some idea of the architecture of the database, which in turn drives the Model for my application.

To take a step back for a second, I’m developing the application using the CakePHP framework which uses MVC architecture.

As you may have guessed I have specimen, aliquot, boxes and freezers tables. In turn then, I have Specimen, Aliquot, Box and Freezer Models.

The trick here is that I want to alert users when there are aliquots in the system that have not yet been assigned to boxes. It’s a simple query:

SELECT COUNT(aliquot.id)
FROM aliquots
WHERE aliquots.box_id IS NULL

The problem is that I want the number of unstored aliquots to be displayed on every page in the left column as a persistent reminder that there are are aliquots that need to be put away. I want to do that in a way that maintains the MVC architecture and doesn’t violate the DRY philosophy.

Since the query is run on the aliquots table and each view is generally specific to it’s own model, I either have to run a recursive query to access data across models–which adds overhead–or implement the solution below which lightens the load a bit and is a more elegant bit of code. (Tip of the hat to Jon Bennet for offering the solution.)

The solution involves CakePHP’s requestAction().

I can define the method in my aliquots controller and call it from anywhere. So if aliquots_controller.php has a method that retrieves the data from the model (in this case called ‘unstored’) I can simply put the following code into my layout:

$unstored = $this-&gt;requestAction('aliquots/unstored');
if(!empty($unstored)) {
echo $html-&gt;link('<strong>' . $unstored['unstored'] . ' aliquots have not been stored.</strong>', '/aliquots/store');
}

I only have to define the method once to use it throughout my application. Problem solved.

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Posted in About the Author, CakePHP, PHP, This Site, web development | No Comments »