###### 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 { public $title = ''; public $content = ''; public $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 { 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 will be a lower case version of your class name. For example, if your class is this:: 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 :doc:`controller <controllers>` functions. To load a model you will use the following method:: $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 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 :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'] = 'mysqli'; $config['dbprefix'] = ''; $config['pconnect'] = FALSE; $config['db_debug'] = TRUE; $this->load->model('Model_name', '', $config);