Extending The Controller Class for Common Code

I’d like to thank Noah Botimer for his interest and assistance. I’ve now changed the way I’ve constructed my fledgling web application. This code replaces the code shown in Getting Started With CodeIgniter 5.

Because I wanted to have a certain amount of common code in all controllers – calls to two functions called setup_assets and setup_system_data in my case, I have now extended the controller class by using the MY_ technique.

The MVC example is below.

The Extended Controller Class

This is placed in system/application/libraries/MY_Controller.php

<?php
class MY_Controller extends Controller {

    function __construct(){
      parent::__construct();
      $this->setup_assets();
      $this->setup_system_data();
    }

    function setup_assets(){
      $this->load->database();
      $this->load->model('systemdata');
      $this->data['base_url'] = $this->systemdata->get_base_url();
      $this->data['cssmain'] = $this->systemdata->get_cssmain_filespec();
      $this->data['pdf'] = $this->systemdata->get_pdf_filespec();
      $this->data['cssIE6'] = $this->systemdata->get_cssie6_filespec();
      $this->data['cssIE7'] = $this->systemdata->get_cssie7_filespec();
      $this->data['scripts'] = $this->systemdata->get_scripts_filespec();
      $this->data['css'] = $this->systemdata->get_css_filespec();
      $this->data['xml'] = $this->systemdata->get_xml_filespec();
      $this->data['flash'] = $this->systemdata->get_flash_filespec();
      $this->data['site_images'] = $this->systemdata->get_site_images_filespec();
      $this->data['images'] = $this->systemdata->get_images_filespec();
      $this->data['public_status'] = $this->systemdata->get_public_status();
      $this->data['member_status'] = $this->systemdata->get_member_status();
    }

    function setup_system_data(){
      $this->data['page_name'] = $this->systemdata->get_page_name();
      $this->data['copy_right_range'] = $this->systemdata->getcopyrightrange();
      $this->data['current_year'] = $this->systemdata->selectcurrentyear();
      $this->data['version'] = $this->systemdata->selectwebsiteversion();
      $this->data['global_phone'] = $this->systemdata->selectglobalphone();
      $this->data['uk_phone'] = $this->systemdata->selectukphone();
      $this->data['any_phone'] = $this->systemdata->selectanyphone();
    }
}
?>

A Controller

<?
class Privacy extends MY_Controller {
  var $data;

  function Privacy(){
    parent::__construct();
    $this->load->helper('url');
  }

  function index(){
    $this->load->view('publicuser/viewprivacy', $this->data);
  }

}
?>

One Controller Per View in CodeIgniter

So how do you break a website into views and controllers exactly? If you read the CodeIgniter forums people have devised lots of different ways of tackling the controller problem.

For me, taking the project I am currently working on, I find it easy enough to think in terms of objects for the tours, the shopping cart, a customer and so on. But the static web pages – the views that end up being your about, contact me, terms and conditions and privacy pages – how do you break down the controllers for those?

This is an especially testing question because you are likely to hit it pretty quickly when you decide to learn CodeIgniter and the MVC approach at the same time. You’re likely after all to want to start with simple pages.

First I thought – I’ll do one controller per view no matter how straightforward the page content. Then as soon as I had decided that, doubts crept in. No way! That’s absurd. How can you have one controller for the about page, another for the company history page and yet another for the terms and conditions page. They’d be practically the same!

Changed My Mind – One Catchall Controller for All Static Views

So I set about creating a common controller that would control all static pages. By static, I mean pages that only contained text that would rarely change.

Hmm – what was I going to call it – maybe the content controller (content.php), or maybe the static controller (static.php)? I was having trouble finding a good name for this catchall controller. This seemed to me like a sign I was on the wrong track.

The next thought that came to mind was – well hang on, I might want to add something data flavoured to the About page one day – I don’t know – it might be a feed of the client’s Twitter tweets. What then, the about page would suddenly no longer be hopelessly static and if I’d had the foresight to create one controller per page at the start, I wouldn’t have to change the general content controller for all static pages, just because one needed more.

Back to One Controller Per View

I am now back to the one page per controller idea. This meant however that each controller for each static page, necessarily contained a lot of repeated code. I hunted through the CodeIgniter forums for the best way to address this, and the answer appeared to be to use a helper.

I say ‘appeared’ as the CI forums can get very technical and sometimes, I am not not sure what they are all talking about. Hence the need to write this stuff on my blog I suppose.

Here’s a list of forum posts that I found useful whilst getting my head around this.

• How Models Are Used
• MVC Questions
• Help With Controllers

Using A Helper for Common Controller Code

If you decide to use one controller per view, you can cut down on repeated code by putting the common controller set up code (data loads etc) into a specially written helper. I wrote one called commoncontrol_helper.php and put it in the application/helpers directory. My helper looks like this, and contains (currently) one function called setup_assets. This follows on from my previous posts in this series.

<?php

  function setup_assets($theobject){
    $theobject->load->model('systemdata');
    $theobject->load->database();
    $theobject->data['css'] = $theobject->systemdata->get_css_filespec();
    $theobject->data['pdf'] = $theobject->systemdata->get_pdf_filespec();
    $theobject->data['cssIE6'] = $theobject->systemdata->get_cssie6_filespec();
    $theobject->data['cssIE7'] = $theobject->systemdata->get_cssie7_filespec();
    $theobject->data['scripts'] = $theobject->systemdata->get_scripts_filespec();
    $theobject->data['xml'] = $theobject->systemdata->get_xml_filespec();
    $theobject->data['flash'] = $theobject->systemdata->get_flash_filespec();

    $theobject->data['base_url'] = $theobject->systemdata->get_base_url();
    $theobject->data['site_images'] = $theobject->systemdata->get_site_images_filespec();
    $theobject->data['images'] = $theobject->systemdata->get_images_filespec();
    $theobject->data['public_status'] = $theobject->systemdata->get_public_status();
    $theobject->data['member_status'] = $theobject->systemdata->get_member_status();
    $theobject->data['page_name'] = $theobject->systemdata->get_page_name();
    $theobject->data['currentyear'] = $theobject->systemdata->selectcurrentyear();
}
?>

And consequently, a controller that uses this helper will look like this :

<?php
class Privacy
  extends Controller {
  var $data;

  function Privacy(){
    parent::Controller();
    $this->load->helper('url');
    $this->load->helper('commoncontrol');
    setup_assets($this);
  }

  function index(){
    $this->load->view('publicuser/viewprivacy', $this->data);
  }

}
?>

Getting The Environment Set Up

Last time, we installed the software and altered the config.php file by adding two lines (one commented out). Please review Getting Started With CodeIgniter – 1 for details.

If you now visit the home page running locally on your PC, you should see this. Obviously you must substitute your root directory where I have used chaingang3.

Setting up database.php

Most web sites demanding the attentions of CodeIgniter will need a database. I am using MySQL. I created a MySQL database called chaingang3 and set up a username and password for it.

To communicate this to the CI system, edit the database.php file located in the config directory (same place as the config.php file was located).

Add the following lines to database.php, but of course use your own username, password and database name.  The placeholders for these parameters are already in the file, you just have to fill in the values.

$db['default']['hostname'] = "localhost";
$db['default']['username'] = "myusername";
$db['default']['password'] = "mypassword";
$db['default']['database'] = "chaingang3";

Setting Up constants.php

I like to place any constants that I need to have available throughout the web site in the constants.php file. So early in your development you won’t know what these are for the mostpart, but each time you need a new global constant, set it up in here. To start with I will put in the Version number of the site I am developing. This is the site’s 3rd version so I’ll make a suitable constant, and add it to constants.php.

define('WEBSITE_VERSION', '3.0');

Setting Up Custom Functions

As you code, you’ll need to write PHP functions.  There is a special place to put these in CI. Go to system/application/helpers and create a custom helper PHP file with a name like mycustomfunctions_helpers.php.

For example, one function I always add to my custom helper file is something to alert PHP values without having to write the Javascript each time. This is symptomatic of my never using a debugger.  Here it is :

As time goes on, you’ll add more of your own functions to this file.

Sub Directories for Image, CSS, Javascript and Other Files

I put all the images that are part of the web design into a sub directory called site-images and all content images into a sub-directory called images. Further, I like to place all my CSS files into a css sub-directory and Javascript files into a sub-directory called scripts. I follow the same regime for any other special files the web site may need  – like say for example a sub-directory for flash movies, another for PDFs and so on.

To do this, create all your required sub-directories under the CI application directory in a new sub-directory called assets.  Of course you don’t have to call it assets - I do because someone on the CI forums suggested the name. Anyway – I set the following structure up and so I’ll always have somewhere specific to place required files.