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authorKyle Farris <kylefarris@kylefarris.gotdns.org>2011-10-14 21:43:25 +0200
committerKyle Farris <kylefarris@kylefarris.gotdns.org>2011-10-14 21:43:25 +0200
commitad17f4b932b3728c1e299b48f28b3ae0dbdd6b0b (patch)
treefdb357433e76000bdef60c4d18e5ab0540b07aeb /user_guide_src/source/general/models.rst
parentdb46d02ac23b8e0bc2416e197494d3b795b57530 (diff)
parenta2125a5d830fd390b4cf35f77e9bb0558cfa2dd7 (diff)
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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 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 :doc:`Active
+ Record <../database/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 :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);
+
+