Урок - Модели/Models.

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

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 Blogmodel extends CI_Model {

    var $title   = '';
    var $content = '';
    var $date    = '';

    function __construct()
    {
        // Call the Model constructor
        parent::__construct();
    }
    
    function get_last_ten_entries()
    {
        $query = $this->db->get('entries', 10);
        return $query->result();
    }

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

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

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

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

}

Note: The functions in the above example use the Active Record database functions.

Note: For the sake of simplicity in this example we're using $_POST directly. This is generally bad practice, and a more common approach would be to use the Input Class $this->input->post('title')

Anatomy of a Model

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

The basic prototype for a model class is this:

class Model_name extends CI_Model {

    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 will be a lower case version of your class name. For example, if your class is this:

class User_model extends CI_Model {

    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 functions. To load a model you will use the following function:

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

If your model is located in a sub-folder, include the relative path from your models folder. 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 functions using an object with the same name as your class:

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

$this->Model_name->function();

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

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

$this->fubar->function();

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

class Blog_controller extends CI_Controller {

    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 function 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'] = "mysql";
    $config['dbprefix'] = "";
    $config['pconnect'] = FALSE;
    $config['db_debug'] = TRUE;

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