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######
Models
######
Models are **optionally** available for those who want to use a more
traditional MVC approach.
.. contents:: Page Contents
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 {
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 :doc:`Active
Record <../database/query_builder>` 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 :doc:`Input Class <../libraries/input>`
$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
:doc:`controller <controllers>` 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 :doc:`described
here <../database/connecting>`, 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);
|
