How To Work With Codeigniter Caching In PHP

For websites/web applications, caching plays a very important role. Today, in this tutorial, I will explain how we can start using CodeIgniter caching techniques to improve our web application to a new level. I am assuming you have some CodeIgniter basics knowledge already and have the experience to write simple codes using Codeigniter standards.

Why Caching?

“I am coding, and my code is working well; why do I need to implement caching techniques?”
Well, this kind of thinking is natural. To understand the main concern behind this, we will need to come out from the domain of “only coding the functionality” to a little higher level of thinking. The two most important factors are as follows:

Applications Performance: It’s vital because the visitors (your customers) are experiencing it, to whom your application is for. If your application is giving your users a boring/slow performance result, it’s gonna be a lot noticeable/annoying to them. The faster web application always brings peace to a visitor’s mind.

Reduce Server Overhead: The more your web application/site becomes popular, the more your server has to work more. It’s always better to lessen the server’s computing/communication load as much as possible. Otherwise, for overloaded or spike traffic, the server may crash often. You can have a highly configured server to handle this, but it will cost a lot which you don’t need to do at all. As this doesn’t always happen, most of the time, server capability will remain unused, thus wasted.

Caching can be a good answer to these. We will see how CodeIgniter caching can help in these regards to our websites/applications.

 

Read The Complete PHP CodeIgniter Tutorials Series By CodeSamplez.com

 

How Many Different Type Of Caching Can be Implemented?

In a traditional web application architecture, there are a few layers where caching techniques can be implemented, such as:

• Browser caching
• View page caching
• Object caching
• Database caching

Luckily most of them can be controlled by your server application. let’s dig into them one by one.

CodeIgniter Cache Control Technique For Browser:

By default, web browsers do cache the results that our server generates. Here, we can tell the browser not to cache. Usually, we won’t want to prevent the browser from caching except for some special cases where our outputs are updated very often. So, instead of setting these commands as global/base controller, let’s practice using it only in the controllers/controller functions where it’s needed. You can use the following code snippets only when you want to prevent caching for browsers:

$this->output->set_header("Cache-Control: no-store, no-cache, must-revalidate");
$this->output->set_header("Cache-Control: post-check=0, pre-check=0");
$this->output->set_header("Pragma: no-cache");Code language: PHP (php)

CodeIgniter Caching For View Pages:

OK, so let us move one level deeper. We now want to cache the output CodeIgniter is generating for visitors. That means. The result of ‘controller function+view code’ combined. Well, if you are using any third-party view render-er such as smarty template engine, then you don’t have to worry at all; it will take care of the view caching. If you are not using any, then CodeIgniter’s internal support is very helpful. Use the code example below in the controller function where you want caching:

function my_controller_function()
{
       //your controller codes goes her.....

       $this->output->cache(n);
       //n = number of minutes to cache output

       //your controller codes goes here....
}Code language: PHP (php)

Notice that I have mentioned in the code that you can set this in any place of your controller function. It doesn’t matter where you place it; it will cause caching of the entire controller’s functionality. Check out CodeIgniter documentation on web page caching for more details descriptions.

CodeIgniter PHP Objects Caching:

Well, now we are about to use some advance level CodeIgniter caching techniques. Codeigniter can internally interpret with other third-party cache drivers to get the most out of your application. This usually includes support for APC, Memcache and file/disk-based cache. All your caching code will be similar; you just will have to change the driver identifier to the proper one. It makes it very easy/efficient to switch between cache drivers.

Moving the application to a new server which doesn’t support any caching?
Well, you might be wondering what we will do in such cases. Would we change the code to disable all cache? No, we won’t need to. For this purpose, Codeigniter has support for “Dummy Cache” mode. It doesn’t cache anything, really, but your code can be unchanged. Isn’t it cool?

Let’s see simple use of PHP object caching in Codeigniter. A typical caching code snippet would be as follows:

function my_function()
{
     if ( ! $cache_data = $this->cache->get('cache_key'))
     {
          //here goes your codes...
          $some_object = (object) NULL;
          $some_object->test_property = "test date";

          // Save into the cache for 2 minutes
          $this->cache->save('cache_key', $some_object, 120);
          $cache_data = $some_object;
     }
     return $cache_data;
}Code language: PHP (php)

Whenever the above function is called, it will return data from its cache for up to 2 minutes, and then the cache will expire. Then it will execute all logic you entered to generate new objects. This can be placed anywhere inside controller functions, model functions or libraries, depending on your requirements. Check Codeigniter documentation on caching library for more in-depth knowledge.

CodeIgniter Caching For Database Results:

Yeah, Codeigniter does provide a very nice way to cache the database query results as well! It’s very helpful to balance the load on your database by caching the ‘most frequently used’/’less frequently updated’ database contents. If you are using some kind of third-party database abstraction layer such as doctrine ORM with CodeIgniter, then you won’t need to worry about this level of caching as it’s already provided by them. But, if you are not, and are using CodeIgniter active record or so, then you can use this caching technique to boost the performance of your application.

Luckily, using this is also as simple as other CodeIgniter functionality. We just need to provide a command to cache results when we are performing some database operations:

$this->db->cache_on();

$result1 = $this->db->query("SELECT * FROM some_table");

$this->db->select("id");
$this->db->from("some_table");
$result2 = $this->db->get();Code language: PHP (php)

as soon as we instruct to cache ‘on’, it will start caching all the results following it. If you need somewhere to disable caching, just use the ‘cache_off’ function before the execution. See complete documentation on database caching for more information.

I hope this brief CodeIgniter caching tutorial will help you understand and improve your web application to be more robust/scalable. Do not hesitate to ask if you have any questions/comments. Happy coding 🙂