5547-CakePHP-tutorial-no-5-from-IBM.pdf

Cook up Web sites fast with CakePHP, Part 5: Adding cache

03/06/2007 08:19 PM

Cook up Web sites fast with CakePHP, Part 5:

Adding cache

A good way to improve the performance of your apps

Level: Intermediate

Duane O'Brien ( d@duaneobrien.com ), PHP developer, Freelance

16 Jan 2007

CakePHP is a stable production-ready, rapid-development aid for building Web sites in PHP.

This " Cook up Web sites fast with CakePHP " series shows how to build an online product

catalog using CakePHP. Part 1 focuses on getting CakePHP up and running, and Part 2

demonstrates how to use Scaffolding and Bake. Part 3 shows how to use CakePHP's Sanitize and

Security components to help secure your user-submitted data, and Part 4 focuses on the Session

component of CakePHP. Here in Part 5, you will learn how to use CakePHP's Sanitize and

Security components to help secure your user-submitted data, and you will learn how to handle

invalid requests.

Introduction

This series is designed for PHP application developers who want to start using CakePHP to make their lives

easier. In the end, you will have learned how to install and configure CakePHP, the basics of Model-View-

Controller (MVC) design, how to validate user data in CakePHP, how to use CakePHP Helpers, and how to

get an application up and running quickly using CakePHP. It might sound like a lot to learn, but don't worry --

CakePHP does most of it for you.

This article assumes you have already completed Part 1 , Part 2 , Part 3 , Part 4 , and that you still have the

working environment you set up for those pieces. If you do not have CakePHP installed, you should run

through Parts 1 and 2 before continuing.

It is assumed that you are familiar with the PHP programming language, have a fundamental grasp of database

design, and are comfortable getting your hands dirty.

System requirements

Before you begin, you need to have an environment in which you can work. CakePHP has minimal server

requirements:

1 An HTTP server that supports sessions (and preferably mod_rewrite). This article was written using

Apache V1.3 with mod_rewrite enabled.

2 PHP V4.3.2 or greater (including PHP V5). This article was written using PHP V5.0.4.

3 A supported database engine. Today, this means MySQL, PostgreSQL, or use of a wrapper around

ADODB. This article was written using MySQL V4.1.15.

You'll also need a database and database user ready for your application to use. This article provides the

syntax for creating any necessary tables in MySQL.

The simplest way to download CakePHP is to visit CakeForge.org and download the latest stable version. This

tutorial was written using V1.1.8. (Nightly builds and copies straight from Subversion are also available.

Details are in the CakePHP Manual (see Resources ).)

http://www-128.ibm.com/developerworks/opensource/library/os-php-cake5/

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Tor so far

In Part 4 , you were given an opportunity to streamline Tor . How did you do?

Adding the Favorites Action and View

To view the Favorites list, you need to add a favorites action to the users controller. It might look something

like Listing 1.

Listing 1. Adding a favorites action to the users controller

function favorites () {

$username = $this->Session->read('user');

$favorites = array();

if ($username)

{

$this->User->recursive = 2;

$results = $this->User->findByUsername($username);

foreach($results['Product'] as $product)

{

$favorites[] = array('Product' => $product, 'Dealer' => $product['Dealer']);

}

$this->set('products', $favorites);

} else {

$this->redirect('/users/login');

}

Note the redirection if the user is not logged in. This keeps the user from seeing an error when viewing the

page without logging in.

You would also need a favorites.html in the app/views/users/ directory. It might look something like this:

Listing 2. Favorites.html

<h2>Your Favorite Products</h2>

<?php

echo $this->renderElement('products_table', array('products' => $products) );

All the view really needs to do is show the products table. However, right now, the products all show up with

an Add To Favorites link, which is silly, considering you are looking at your list of favorites. It should say

Remove From Favorites .

Putting in the Remove From Favorites Link

Your other task was to put in a Remove From Favorites link in the products table, setting it up so that users

saw the Remove link if a product was in their favorites list, and an Add link if the product was not in their

favorites list. Taking a look at the products table again, the following section is the most important.

http://www-128.ibm.com/developerworks/opensource/library/os-php-cake5/

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Listing 3. Products table

<?php

if ( isset($ajax) ) {

echo $ajax->link('Add to Favorites', '/products/add_to_favorites/' .

$product['Product']['id'], array('update'=>'updated', 'loading' =>

"Element.show('loading')",'complete' => "Element.hide('loading')"));

}

The Remove From Favorites link will be much the same, as shown below.

Listing 4. Remove from Favorites link

echo $ajax->link('Remove from Favorites', '/products/remove_from_favorites/' .

$product['Product']['id'], array('update'=>'updated', 'loading' =>

"Element.show('loading')",'complete' => "Element.hide('loading')"));

You will also need the removeFromFavorites action in the products controller.

Listing 5. The removeFromFavorites action

function removeFromFavorites($id) {

$username = $this->Session->read('user');

$success = false;

$user = $this->Product->User->findByUsername($username, 'User.id');

$this->Product->User->id = $user['User']['id'];

$success = $this->Product->User->removeFavorite($id);

if ( $this->RequestHandler->isAjax() ) {

$this->set('products', $this->Product->findAll());

} else {

if ( $success ) {

$this->Session->setFlash('Removed product from favorites');

$this->redirect('/users/favorites');

} else {

$this->Session->setFlash('Access denied');

$this->redirect('/products/index');

}

And likewise, the removeFavorite method in the users controller must be created.

Listing 6. Creating the removeFavorite method

function removeFavorite($product_id) {

if($this->getID()) {

$user = $this->read();

$fav = array();

foreach($user['Product'] as $product) {

if ($product_id != $product['id'])

{

$fav[] = $product['id'];

}

$user['Product'] = array('Product'=> $fav);

if($this->save($user)) {

return true;

http://www-128.ibm.com/developerworks/opensource/library/os-php-cake5/

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} else {

return false;

}

return false;

}

As you noticed, when you view the favorites list, Add to Favorites is displayed. Instead, the user should see

the Remove from Favorites button for products they already have added to their favorites list. How would

you do that?

Caching

Conceptually, caching can sometimes be confusing. There are many types of caching, and each presents its

own set of challenges and benefits. It is important to understand in this context what is meant by caching.

What does caching mean?

Generally, caching happens anytime a request is made, and the responding application says, "I don't have to

go get that. I've already got one." Most of the time, when a computer user hears the word "cache," he thinks of

a browser's cache. Typically, in order to speed up the user experience, your browser will keep copies of what

it believes are static files -- generally images, stylesheets, static HTML, and script files. While this type of

caching can sometimes cause problems for developers of Web applications, this type of caching is not our

focus here.

Another example of caching would be when the browser makes a request of your Web application for some

content. If your Web application uses caching, it could respond to the request with a previously generated

copy of the content, eliminating the resource overhead involved in generating the content a second time. This

is the type of caching this article will focus on.

Cache why?

Generally, you would use caching in your application for two reasons. One, it helps reduce resource

consumption on your server. While the savings may be small in most cases, for high-traffic sites serving

requests in significant volume, these small savings quickly add up to significant performance benefits. The

second reason is typically speed. Because your application doesn't have to go through the process of

regenerating the content for the request, the content can be served much more quickly. Again, while the

savings may be small in most cases, high-traffic sites can quickly realize speed benefits by using caching.

Cache how?

OK -- you're sold. You are ready to cache anything and everything. How do you do it? What does CakePHP

give you to make it easy?

For starters, you need to turn caching on. By default, it's disabled. You can enable it in app/config/core.php --

look for the following entry: define('CACHE_CHECK', false); and change it to

define('CACHE_CHECK', true); .

By setting this value to true you are telling CakePHP that caching is now in play. Go ahead and do that now,

so you can set up caching later. You're not done yet: you have to tell CakePHP exactly what you want cached,

and for how long.

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Cache what?

Having turned caching on, you have to specify what you want cached. This starts in the controller for the

views you want to cache by adding cache to the helpers array. For example, if you want to cache the

products views, you would have to have cache in the helpers array for the products controller. When you

built the products controller for Tor, you specified that the HTML and form helpers were in use. Adding cache

to this list, the helpers array would look like this: var $helpers = array('Html',

'Form', 'Cache' ); .

Now that the cache helper is in use, you need to specify exactly what you want cached. There are several

ways you can do this, but all of them hinge on the $cacheAction array.

Cache a specific request

Suppose you wanted to cache a specific request. Suppose there are three or four products that get high traffic

on the view action, and you want to cache just the "view" views for these products. In this case, you would

specify the requests you want to cache as array keys for $cacheAction and specify the length of time as

the value for the key. The $cacheAction array is a class variable, like the $helpers array. To cache

these specific views, $cacheAction might look like Listing 7.

Listing 7. $cacheAction

var $cacheAction = array (

'view/1/' => 3600,

'view/2/' => 3600,

'view/3/' => 3600

);

This $cacheAction is telling CakePHP to cache the "view" views for products 1-3 for 3,600 seconds

(one hour). The length of time you specify can be any format that strtotime() can interpret. You could

just as easily say 1 hour .

Cache a whole action

Maybe it's not enough to just cache a few products. Perhaps you want to cache all the views for a particular

action. Suppose you want to use caching on the views for the edit action. To do so, you would specify the

action as an array key and the length of time to keep the views in cache much like you did above.

var $cacheAction = array (

'edit/' => '+1 hour'

);

You can even mix and match the two.

Listing 8. Mixing and matching

var $cacheAction = array (

'view/1/' => 3600,

'view/2/' => 3600,

'view/3/' => 3600,

'edit/' => '+1 hour'

);

That helps save some time. Now you have cached the "view" views for the most commonly viewed products

and all of the edit views. But maybe you want to do more.

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