codeigniter & mvc

CodeIgniter & MVC

Jamshid HashimiTrainer, Cresco Solution

http://www.jamshidhashimi.com [email protected] @jamshidhashimi ajamshidhashimi

Afghanistan Workforce Development Program

http://www.jamshidhashimi.com/

mailto:[email protected]

Agenda

• Supported Features• Understanding MVC• Application Flow Chart• CodeIgniter URLS• CodeIgniter Controllers• Views• Models• Helpers• Libraries• Hooks

Supported Feaures• Model-View-Controller Based System• Extremely Light Weight• Full Featured database classes with support for several platforms.• Active Record Database Support• Form and Data Validation• Security and XSS Filtering• Session Management• Email Sending Class. Supports Attachments, HTML/Text email,

multiple protocols (sendmail, SMTP, and Mail) and more.• Image Manipulation Library (cropping, resizing, rotating, etc.).

Supports GD, ImageMagick, and NetPBM

Supported Feaures

• File Uploading Class• FTP Class• Localization• Pagination• Data Encryption• Benchmarking• Full Page Caching• Error Logging• Application Profiling• Calendaring Class• User Agent Class

Supported Feaures

• Zip Encoding Class• Template Engine Class• Trackback Class• XML-RPC Library• Unit Testing Class• Search-engine Friendly URLs• Flexible URI Routing• Support for Hooks and Class Extensions• Large library of "helper" functions

Understanding MVC

• CodeIgniter is based on the Model-View-Controller development pattern. MVC is a software approach that separates application logic from presentation. – The Model represents your data structures. – The View is the information that is being presented to

a user. – The Controller serves as an intermediary between the

Model, the View, and any other resources needed to process the HTTP request and generate a web page.

Application Flow Chart

CodeIgniter URLS

• By default, URLs in CodeIgniter are designed to be search-engine and human friendly.

• CodeIgniter uses a segment-based approach.

example.com/news/article/my_article

CodeIgniter URLS

• The first segment represents the controller class that should be invoked.

• The second segment represents the class function, or method, that should be called.

• The third, and any additional segments, represent the ID and any variables that will be passed to the controller.

example.com/class/function/ID

CodeIgniter URLS

• Removing index.php

RewriteEngine onRewriteCond $1 !^(index\.php|images|robots\.txt)RewriteRule ^(.*)$ /index.php/$1 [L]

CodeIgniter Controllers

• A Controller is simply a class file that is named in a way that can be associated with a URI.

• When a controller's name matches the first segment of a URI, it will be loaded.

<?phpclass Blog extends CI_Controller {

public function index(){

echo 'Hello World!';}

}?>


• The second segment of the URI determines which function in the controller gets called.


public function index(){

echo 'Hello World!';}

public function comments(){

echo 'Look at this!';}

}?>


• If your URI contains more then two segments they will be passed to your function as parameters.

<?phpclass Products extends CI_Controller { public function shoes($sandals, $id) { echo $sandals; echo $id; }}?>


• Constructors are useful if you need to set some default values, or run a default process when your class is instantiated. Constructors can't return a value, but they can do some default work.

<?phpclass Blog extends CI_Controller { public function __construct() { parent::__construct(); // Your own constructor code }}?>

Views

• A view is simply a web page, or a page fragment, like a header, footer, sidebar, etc. In fact, views can flexibly be embedded within other views (within other views, etc., etc.) if you need this type of hierarchy.

$this->load->view('view.php');

Views

• CodeIgniter will intelligently handle multiple calls to $this->load->view from within a controller.

<?phpclass Page extends CI_Controller { function index() { $data['page_title'] = 'Your title'; $this->load->view('header'); $this->load->view('menu'); $this->load->view('content', $data); $this->load->view('footer'); }}?>

Views

• Data is passed from the controller to the view by way of an array or an object in the second parameter of the view loading function.

$data = array( 'title' => 'My Title', 'heading' => 'My Heading', 'message' => 'My Message');$this->load->view('blogview', $data);

Views

• The data array you pass to your view files is not limited to simple variables. You can pass multi dimensional arrays, which can be looped to generate multiple rows.


function index(){

$data['todo_list'] = array('Clean House', 'Call Mom', 'Run Errands');

$data['title'] = "My Real Title";$data['heading'] = "My Real Heading";$this->load->view('blogview', $data);

}}?>

Views

<html><head><title><?php echo $title;?></title></head><body><h1><?php echo $heading;?></h1><h3>My Todo List</h3><ul><?php foreach ($todo_list as $item):?><li><?php echo $item;?></li><?php endforeach;?></ul></body></html>

Models

• Models are PHP classes that are designed to work with information in your database.

class Model_name extends CI_Model { function __construct() { parent::__construct(); }}

Models

$this->load->model('Model_name');

$config['hostname'] = "localhost";$config['username'] = "myusername";$config['password'] = "mypassword";$config['database'] = "mydatabase";$config['dbdriver'] = "mysql";$config['dbprefix'] = "";$config['pconnect'] = FALSE;$config['db_debug'] = TRUE;

Helpers

• Helpers, as the name suggests, help you with tasks. Each helper file is simply a collection of functions in a particular category.

• Unlike most other systems in CodeIgniter, Helpers are not written in an Object Oriented format. They are simple, procedural functions. Each helper function performs one specific task, with no dependence on other functions.

Helpers

$this->load->helper('url');

$this->load->helper( array('helper1', 'helper2', 'helper3') );

<?php echo anchor('blog/comments', 'Click Here');?>

Helpers

• Extending Helpers– To "extend" Helpers, create a file in your

application/helpers/ folder with an identical name to the existing Helper, but prefixed with MY_

– The term "extend" is used loosely since Helper functions are procedural and discrete and cannot be extended in the traditional programmatic sense.

Libraries

• All of the available libraries are located in your system/libraries folder.

$this->load->library('class name');

$this->load->library(array('email', 'table'));

Libraries

• CodeIgniter permits your libraries to extend native classes if you simply need to add some functionality to an existing library. Or you can even replace native libraries just by placing identically named versions in your application/libraries folder. – You can create entirely new libraries.– You can extend native libraries.– You can replace native libraries.

Libraries

• File names must be capitalized. For example: Myclass.php

• Class declarations must be capitalized. For example: class Myclass

• Class names and file names must match.

Libraries<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed'); class Someclass { public function some_function() { }}/* End of file Someclass.php */

$this->load->library('someclass');

$this->someclass->some_function();

Libraries

• You can use class constructor for initializing data

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');class Someclass { public function __construct($params) { // Do something with $params }}?>

Libraries

• Utilizing CodeIgniter Resources

$CI =& get_instance();

$CI->load->helper('url');$CI->load->library('session');$CI->config->item('base_url');etc.

Libraries

• Replacing Native Libraries with Your Versions– To use this feature you must name the file and the

class declaration exactly the same as the native library.

– Note that most native classes are prefixed with CI_.

class CI_Email {

}

Libraries

• If all you need to do is add some functionality to an existing library - perhaps add a function or two - then it's overkill to replace the entire library with your version. In this case it's better to simply extend the class. Extending a class is nearly identical to replacing a class with a couple exceptions: – The class declaration must extend the parent class.– Your new class name and filename must be prefixed

with MY_

Libraries

• The parent constructor must be called, whenever we want to have to use a constructor in our own library.

class MY_Email extends CI_Email { public function __construct() { parent::__construct(); }}

Libraries

• Setting your own prefix– To set your own sub-class prefix, open your

application/config/config.php file and look for this item:

$config['subclass_prefix'] = 'MY_';

Hooks

• CodeIgniter's Hooks feature provides a means to tap into and modify the inner workings of the framework without hacking the core files.– For example, you might want to run a script right

before your controllers get loaded, or right after, or you might want to trigger one of your own scripts in some other location.

$config['enable_hooks'] = TRUE;

Hooks

• Hooks are defined in application/config/hooks.php file. Each hook is specified as an array with this prototype:

$hook['pre_controller'] = array('class' => 'MyClass','function' => 'Myfunction','filename' => 'Myclass.php','filepath' => 'hooks','params' => array('milk', 'tea',

'fruit'));

Hooks• class The name of the class you wish to invoke. If you prefer to

use a procedural function instead of a class, leave this item blank.• function The function name you wish to call.• filename The file name containing your class/function.• filepath The name of the directory containing your script. Note:

Your script must be located in a directory INSIDE your application folder, so the file path is relative to that folder. For example, if your script is located in application/hooks, you will simply use hooks as your filepath. If your script is located in application/hooks/utilities you will use hooks/utilities as your filepath. No trailing slash.

• params Any parameters you wish to pass to your script. This item is optional.

Hooks

• Hook Points– pre_system: Called very early during system execution. Only

the benchmark and hooks class have been loaded at this point. No routing or other processes have happened.

– pre_controller: Called immediately prior to any of your controllers being called. All base classes, routing, and security checks have been done.

– post_controller_constructor: Called immediately after your controller is instantiated, but prior to any method calls happening.

– post_controller: Called immediately after your controller is fully executed.

Hooks– display_override: Overrides the _display() function, used to

send the finalized page to the web browser at the end of system execution. This permits you to use your own display methodology. Note that you will need to reference the CI superobject with $this->CI =& get_instance() and then the finalized data will be available by calling $this->CI->output->get_output()

– cache_override: Enables you to call your own function instead of the _display_cache() function in the output class. This permits you to use your own cache display mechanism.

– post_system: Called after the final rendered page is sent to the browser, at the end of system execution after the finalized data is sent to the browser.

QUESTIONS?

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