Models

Models are optionally available for those who want to use a more traditional MVC approach.

Page Contents

• Models
  • What is a Model?
  • Anatomy of a Model
  • Loading a Model
  • Auto-loading Models
  • Connecting to your Database

What is a Model?

Models are PHP classes that are designed to work with information in your database. For example, let’s say you use CodeIgniter to manage a blog. You might have a model class that contains functions to insert, update, and retrieve your blog data. Here is an example of what such a model class might look like:

class Blog_model extends CI_Model {

        public $title;
        public $content;
        public $date;

        public function __construct()
        {
                // Call the CI_Model constructor
                parent::__construct();
        }

        public function get_last_ten_entries()
        {
                $query = $this->db->get('entries', 10);
                return $query->result();
        }

        public function insert_entry()
        {
                $this->title    = $_POST['title']; // please read the below note
                $this->content  = $_POST['content'];
                $this->date     = time();

                $this->db->insert('entries', $this);
        }

        public function update_entry()
        {
                $this->title    = $_POST['title'];
                $this->content  = $_POST['content'];
                $this->date     = time();

                $this->db->update('entries', $this, array('id' => $_POST['id']));
        }

}

Anatomy of a Model

Model classes are stored in your application/models/ directory. They can be nested within sub-directories if you want this type of organization.

The basic prototype for a model class is this:

class Model_name extends CI_Model {

        public function __construct()
        {
                parent::__construct();
        }

}

Where Model_name is the name of your class. Class names must have the first letter capitalized with the rest of the name lowercase. Make sure your class extends the base Model class.

The file name must match the class name. For example, if this is your class:

class User_model extends CI_Model {

        public function __construct()
        {
                parent::__construct();
        }

}

Your file will be this:

application/models/User_model.php

Loading a Model

Your models will typically be loaded and called from within your controller methods. To load a model you will use the following method:

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

If your model is located in a sub-directory, include the relative path from your models directory. For example, if you have a model located at application/models/blog/Queries.php you’ll load it using:

$this->load->model('blog/queries');

Once loaded, you will access your model methods using an object with the same name as your class:

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

$this->model_name->method();

If you would like your model assigned to a different object name you can specify it via the second parameter of the loading method:

$this->load->model('model_name', 'foobar');

$this->foobar->method();

Here is an example of a controller, that loads a model, then serves a view:

class Blog_controller extends CI_Controller {

        public function blog()
        {
                $this->load->model('blog');

                $data['query'] = $this->blog->get_last_ten_entries();

                $this->load->view('blog', $data);
        }
}

Auto-loading Models

If you find that you need a particular model globally throughout your application, you can tell CodeIgniter to auto-load it during system initialization. This is done by opening the application/config/autoload.php file and adding the model to the autoload array.

Connecting to your Database

When a model is loaded it does NOT connect automatically to your database. The following options for connecting are available to you:

• You can connect using the standard database methods described here, either from within your Controller class or your Model class.

• You can tell the model loading method to auto-connect by passing TRUE (boolean) via the third parameter, and connectivity settings, as defined in your database config file will be used:

  $this->load->model('model_name', '', TRUE);
  

• You can manually pass database connectivity settings via the third parameter:

  $config['hostname'] = 'localhost';
  $config['username'] = 'myusername';
  $config['password'] = 'mypassword';
  $config['database'] = 'mydatabase';
  $config['dbdriver'] = 'mysqli';
  $config['dbprefix'] = '';
  $config['pconnect'] = FALSE;
  $config['db_debug'] = TRUE;
  
  $this->load->model('model_name', '', $config);