Models
Models are optionally available for those who want to use a more traditional MVC approach.
- What is a Model?
- Anatomy of a Model
- Loading a Model
- Auto-Loading a Model
- 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 Blogmodel extends Model {
var $title = '';
var $content = '';
var $date = '';
function Blogmodel()
{
// Call the Model constructor
parent::Model();
}
function get_last_ten_entries()
{
$query = $this->db->get('entries', 10);
return $query->result();
}
function insert_entry()
{
$this->title = $_POST['title'];
$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.
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 Model {
function Model_name()
{
parent::Model();
}
}
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 Model {
function User_model()
{
parent::Model();
}
}
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 you 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 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);