diff options
Diffstat (limited to 'user_guide_src/source/general/models.rst')
| -rw-r--r-- | user_guide_src/source/general/models.rst | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/user_guide_src/source/general/models.rst b/user_guide_src/source/general/models.rst new file mode 100644 index 000000000..4e52a9648 --- /dev/null +++ b/user_guide_src/source/general/models.rst @@ -0,0 +1,185 @@ +###### +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);
\ No newline at end of file |