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diff --git a/user_guide_src/source/libraries/loader.rst b/user_guide_src/source/libraries/loader.rst new file mode 100644 index 000000000..bbe2ed530 --- /dev/null +++ b/user_guide_src/source/libraries/loader.rst @@ -0,0 +1,278 @@ +############ +Loader Class +############ + +Loader, as the name suggests, is used to load elements. These elements +can be libraries (classes) :doc:`View files <../general/views>`, +:doc:`Helpers <../general/helpers>`, +:doc:`Models <../general/models>`, or your own files. + +.. note:: This class is initialized automatically by the system so there + is no need to do it manually. + +The following functions are available in this class: + +$this->load->library('class_name', $config, 'object name') +=========================================================== + +This function is used to load core classes. Where class_name is the +name of the class you want to load. Note: We use the terms "class" and +"library" interchangeably. + +For example, if you would like to send email with CodeIgniter, the first +step is to load the email class within your controller:: + + $this->load->library('email'); + +Once loaded, the library will be ready for use, using +$this->email->*some_function*(). + +Library files can be stored in subdirectories within the main +"libraries" folder, or within your personal application/libraries +folder. To load a file located in a subdirectory, simply include the +path, relative to the "libraries" folder. For example, if you have file +located at:: + + libraries/flavors/chocolate.php + +You will load it using:: + + $this->load->library('flavors/chocolate'); + +You may nest the file in as many subdirectories as you want. + +Additionally, multiple libraries can be loaded at the same time by +passing an array of libraries to the load function. + +:: + + $this->load->library(array('email', 'table')); + +Setting options +--------------- + +The second (optional) parameter allows you to optionally pass +configuration setting. You will typically pass these as an array:: + + $config = array ( + 'mailtype' => 'html', + 'charset' => 'utf-8, + 'priority' => '1' + ); + + $this->load->library('email', $config); + +Config options can usually also be set via a config file. Each library +is explained in detail in its own page, so please read the information +regarding each one you would like to use. + +Please take note, when multiple libraries are supplied in an array for +the first parameter, each will receive the same parameter information. + +Assigning a Library to a different object name +---------------------------------------------- + +If the third (optional) parameter is blank, the library will usually be +assigned to an object with the same name as the library. For example, if +the library is named Session, it will be assigned to a variable named +$this->session. + +If you prefer to set your own class names you can pass its value to the +third parameter:: + + $this->load->library('session', '', 'my_session'); + + // Session class is now accessed using: + + $this->my_session + +Please take note, when multiple libraries are supplied in an array for +the first parameter, this parameter is discarded. + +$this->load->view('file_name', $data, true/false) +================================================== + +This function is used to load your View files. If you haven't read the +:doc:`Views <../general/views>` section of the user guide it is +recommended that you do since it shows you how this function is +typically used. + +The first parameter is required. It is the name of the view file you +would like to load. Note: The .php file extension does not need to be +specified unless you use something other than .php. + +The second **optional** parameter can take an associative array or an +object as input, which it runs through the PHP +`extract <http://www.php.net/extract>`_ function to convert to variables +that can be used in your view files. Again, read the +:doc:`Views <../general/views>` page to learn how this might be useful. + +The third **optional** parameter lets you change the behavior of the +function so that it returns data as a string rather than sending it to +your browser. This can be useful if you want to process the data in some +way. If you set the parameter to true (boolean) it will return data. The +default behavior is false, which sends it to your browser. Remember to +assign it to a variable if you want the data returned:: + + $string = $this->load->view('myfile', '', true); + +$this->load->model('Model_name'); +================================== + +:: + + $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'); + + +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'); + + $this->fubar->function(); + +$this->load->database('options', true/false) +============================================ + +This function lets you load the database class. The two parameters are +**optional**. Please see the :doc:`database <../database/index>` +section for more info. + +$this->load->vars($array) +========================= + +This function takes an associative array as input and generates +variables using the PHP `extract <http://www.php.net/extract>`_ +function. This function produces the same result as using the second +parameter of the $this->load->view() function above. The reason you +might want to use this function independently is if you would like to +set some global variables in the constructor of your controller and have +them become available in any view file loaded from any function. You can +have multiple calls to this function. The data get cached and merged +into one array for conversion to variables. + +$this->load->get_var($key) +=========================== + +This function checks the associative array of variables available to +your views. This is useful if for any reason a var is set in a library +or another controller method using $this->load->vars(). + +$this->load->helper('file_name') +================================= + +This function loads helper files, where file_name is the name of the +file, without the _helper.php extension. + +$this->load->file('filepath/filename', true/false) +================================================== + +This is a generic file loading function. Supply the filepath and name in +the first parameter and it will open and read the file. By default the +data is sent to your browser, just like a View file, but if you set the +second parameter to true (boolean) it will instead return the data as a +string. + +$this->load->language('file_name') +=================================== + +This function is an alias of the :doc:`language loading +function <language>`: $this->lang->load() + +$this->load->config('file_name') +================================= + +This function is an alias of the :doc:`config file loading +function <config>`: $this->config->load() + +Application "Packages" +====================== + +An application package allows for the easy distribution of complete sets +of resources in a single directory, complete with its own libraries, +models, helpers, config, and language files. It is recommended that +these packages be placed in the application/third_party folder. Below +is a sample map of an package directory + +Sample Package "Foo Bar" Directory Map +====================================== + +The following is an example of a directory for an application package +named "Foo Bar". + +:: + + /application/third_party/foo_bar + + config/ + helpers/ + language/ + libraries/ + models/ + +Whatever the purpose of the "Foo Bar" application package, it has its +own config files, helpers, language files, libraries, and models. To use +these resources in your controllers, you first need to tell the Loader +that you are going to be loading resources from a package, by adding the +package path. + +$this->load->add_package_path() +--------------------------------- + +Adding a package path instructs the Loader class to prepend a given path +for subsequent requests for resources. As an example, the "Foo Bar" +application package above has a library named Foo_bar.php. In our +controller, we'd do the following:: + + $this->load->add_package_path(APPPATH.'third_party/foo_bar/'); + $this->load->library('foo_bar'); + +$this->load->remove_package_path() +------------------------------------ + +When your controller is finished using resources from an application +package, and particularly if you have other application packages you +want to work with, you may wish to remove the package path so the Loader +no longer looks in that folder for resources. To remove the last path +added, simply call the method with no parameters. + +$this->load->remove_package_path() +------------------------------------ + +Or to remove a specific package path, specify the same path previously +given to add_package_path() for a package.:: + + $this->load->remove_package_path(APPPATH.'third_party/foo_bar/'); + +Package view files +------------------ + +By Default, package view files paths are set when add_package_path() +is called. View paths are looped through, and once a match is +encountered that view is loaded. + +In this instance, it is possible for view naming collisions within +packages to occur, and possibly the incorrect package being loaded. To +ensure against this, set an optional second parameter of FALSE when +calling add_package_path(). + +:: + + $this->load->add_package_path(APPPATH.'my_app', FALSE); + $this->load->view('my_app_index'); // Loads + $this->load->view('welcome_message'); // Will not load the default welcome_message b/c the second param to add_package_path is FALSE + + // Reset things + $this->load->remove_package_path(APPPATH.'my_app'); + + // Again without the second parameter: + $this->load->add_package_path(APPPATH.'my_app', TRUE); + $this->load->view('my_app_index'); // Loads + $this->load->view('welcome_message'); // Loads
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