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| <h1>Controllers</h1> | |
| <p>Controllers are the heart of your application, as they determine how HTTP requests should be handled.</p> | |
| <ul> | |
| <li><a href="#what">What is a Controller?</a></li> | |
| <li><a href="#hello">Hello World</a></li> | |
| <li><a href="#functions">Functions</a></li> | |
| <li><a href="#passinguri">Passing URI Segments to Your Functions</a></li> | |
| <li><a href="#default">Defining a Default Controller</a></li> | |
| <li><a href="#remapping">Remapping Function Calls</a></li> | |
| <li><a href="#output">Controlling Output Data</a></li> | |
| <li><a href="#private">Private Functions</a></li> | |
| <li><a href="#subfolders">Organizing Controllers into Sub-folders</a></li> | |
| <li><a href="#constructors">Class Constructors</a></li> | |
| <li><a href="#reserved">Reserved Function Names</a></li> | |
| </ul> | |
| <a name="what"></a> | |
| <h2>What is a Controller?</h2> | |
| <p><dfn>A Controller is simply a class file that is named in a way that can be associated with a URI.</dfn></p> | |
| <p>Consider this URI:</p> | |
| <code>www.your-site.com/index.php/<var>blog</var>/</code> | |
| <p>In the above example, CodeIgniter would attempt to find a controller named <dfn>blog.php</dfn> and load it.</p> | |
| <p><strong>When a controller's name matches the first segment of a URI, it will be loaded.</strong></p> | |
| <a name="hello"></a> | |
| <h2>Let's try it: Hello World!</h2> | |
| <p>Let's create a simple controller so you can see it in action. Using your text editor, create a file called <dfn>blog.php</dfn>, and put the following code in it:</p> | |
| <textarea class="textarea" style="width:100%" cols="50" rows="10"> | |
| <?php | |
| class Blog extends Controller { | |
| function index() | |
| { | |
| echo 'Hello World!'; | |
| } | |
| } | |
| ?> | |
| </textarea> | |
| <p>Then save the file to your <dfn>application/controllers/</dfn> folder.</p> | |
| <p>Now visit the your site using a URL similar to this:</p> | |
| <code>www.your-site.com/index.php/<var>blog</var>/</code> | |
| <p>If you did it right, you should see <samp>Hello World!</samp>.</p> | |
| <p>Note: Class names must start with an uppercase letter. In other words, this is valid:</p> | |
| <code><?php<br /> | |
| class <var>Blog</var> extends Controller {<br /> | |
| <br /> | |
| }<br /> | |
| ?></code> | |
| <p>This is <strong>not</strong> valid:</p> | |
| <code><?php<br /> | |
| class <var>blog</var> extends Controller {<br /> | |
| <br /> | |
| }<br /> | |
| ?></code> | |
| <p>Also, always make sure your controller <dfn>extends</dfn> the parent controller class so that it can inherit all its functions.</p> | |
| <a name="functions"></a> | |
| <h2>Functions</h2> | |
| <p>In the above example the function name is <dfn>index()</dfn>. The "index" function is always loaded by default if the | |
| <strong>second segment</strong> of the URI is empty. Another way to show your "Hello World" message would be this:</p> | |
| <code>www.your-site.com/index.php/<var>blog</var>/<samp>index</samp>/</code> | |
| <p><strong>The second segment of the URI determines which function in the controller gets called.</strong></p> | |
| <p>Let's try it. Add a new function to your controller:</p> | |
| <textarea class="textarea" style="width:100%" cols="50" rows="15"> | |
| <?php | |
| class Blog extends Controller { | |
| function index() | |
| { | |
| echo 'Hello World!'; | |
| } | |
| function comments() | |
| { | |
| echo 'Look at this!'; | |
| } | |
| } | |
| ?> | |
| </textarea> | |
| <p>Now load the following URL to see the <dfn>comment</dfn> function:</p> | |
| <code>www.your-site.com/index.php/<var>blog</var>/<samp>comments</samp>/</code> | |
| <p>You should see your new message.</p> | |
| <a name="passinguri"></a> | |
| <h2>Passing URI Segments to your Functions</h2> | |
| <p>If your URI contains more then two segments they will be passed to your function as parameters.</p> | |
| <p>For example, lets say you have a URI like this:</p> | |
| <code>www.your-site.com/index.php/<var>products</var>/<samp>shoes</samp>/<kbd>sandals</kbd>/<dfn>123</dfn></code> | |
| <p>Your function will be passed URI segments 3 and 4 ("sandals" and "123"):</p> | |
| <code> | |
| <?php<br /> | |
| class Products extends Controller {<br /> | |
| <br /> | |
| function shoes($sandals, $id)<br /> | |
| {<br /> | |
| echo $sandals;<br /> | |
| echo $id;<br /> | |
| }<br /> | |
| }<br /> | |
| ?> | |
| </code> | |
| <p class="important"><strong>Important:</strong> If you are using the <a href="routing.html">URI Routing</a> feature, the segments | |
| passed to your function will be the re-routed ones.</p> | |
| <a name="default"></a> | |
| <h2>Defining a Default Controller</h2> | |
| <p>CodeIgniter can be told to load a default controller when a URI is not present, | |
| as will be the case when only your site root URL is requested. To specify a default controller, open | |
| your <dfn>application/config/routes.php</dfn> file and set this variable:</p> | |
| <code>$route['default_controller'] = '<var>Blog</var>';</code> | |
| <p>Where <var>Blog</var> is the name of the controller class you want used. If you now load your main index.php file without | |
| specifying any URI segments you'll see your Hello World message by default.</p> | |
| <a name="remapping"></a> | |
| <h2>Remapping Function Calls</h2> | |
| <p>As noted above, the second segment of the URI typically determines which function in the controller gets called. | |
| CodeIgniter permits you to override this behavior through the use of the <kbd>_remap()</kbd> function:</p> | |
| <code>function _remap()<br /> | |
| {<br /> | |
| // Some code here...<br /> | |
| }</code> | |
| <p class="important"><strong>Important:</strong> If your controller contains a function named <kbd>_remap()</kbd>, it will <strong>always</strong> | |
| get called regardless of what your URI contains. It overrides the normal behavior in which the URI determines which function is called, | |
| allowing you to define your own function routing rules.</p> | |
| <p>The overridden function call (typically the second segment of the URI) will be passed as a parameter the <kbd>_remap()</kbd> function:</p> | |
| <code>function _remap(<var>$method</var>)<br /> | |
| {<br /> | |
| if ($method == 'some_method')<br /> | |
| {<br /> | |
| $this->$method();<br /> | |
| }<br /> | |
| else<br /> | |
| {<br /> | |
| $this->default_method();<br /> | |
| }<br /> | |
| }</code> | |
| <a name="output"></a> | |
| <h2>Processing Output</h2> | |
| <p>CodeIgniter has an output class that takes care of sending your final rendered data to the web browser automatically. More information on this can be found in the | |
| <a href="views.html">Views</a> and <a href="../libraries/output.html">Output class</a> pages. In some cases, however, you might want to | |
| post-process the finalized data in some way and send it to the browser yourself. CodeIgniter permits you to | |
| add a function named <dfn>_output()</dfn> to your controller that will receive the finalized output data.</p> | |
| <p><strong>Important:</strong> If your controller contains a function named <kbd>_output()</kbd>, it will <strong>always</strong> | |
| be called by the output class instead of echoing the finalized data directly. The first parameter of the function will contain the finalized output.</p> | |
| <p>Here is an example:</p> | |
| <code> | |
| function _output($output)<br /> | |
| {<br /> | |
| echo $output;<br /> | |
| }</code> | |
| <p class="important">Please note that your <dfn>_output()</dfn> function will receive the data in its finalized state. Benchmark and memory usage data will be rendered, | |
| cache files written (if you have caching enabled), and headers will be sent (if you use that <a href="../libraries/output.html">feature</a>) | |
| before it is handed off to the _output() function. If you are using this feature the page execution timer and memory usage stats might not be perfectly accurate | |
| since they will not take into acccount any further processing you do. For an alternate way to control output <em>before</em> any of the final processing is done, please see | |
| the available methods in the <a href="../libraries/output.html">Output Class</a>.</p> | |
| <a name="private"></a> | |
| <h2>Private Functions</h2> | |
| <p>In some cases you may want certain functions hidden from public access. To make a function private, simply add an | |
| underscore as the name prefix and it will not be served via a URL request. For example, if you were to have a function like this:</p> | |
| <code> | |
| function _utility()<br /> | |
| {<br /> | |
| // some code<br /> | |
| }</code> | |
| <p>Trying to access it via the URL, like this, will not work:</p> | |
| <code>www.your-site.com/index.php/<var>blog</var>/<samp>_utility</samp>/</code> | |
| <a name="subfolders"></a> | |
| <h2>Organizing Your Controllers into Sub-folders</h2> | |
| <p>If you are building a large application you might find it convenient to organize your controllers into sub-folders. CodeIgniter permits you to do this.</p> | |
| <p>Simply create folders within your <dfn>application/controllers</dfn> directory and place your controller classes within them.</p> | |
| <p><strong>Note:</strong> When using this feature the first segment of your URI must specify the folder. For example, lets say you have a controller | |
| located here:</p> | |
| <code>application/controllers/<kbd>products</kbd>/shoes.php</code> | |
| <p>To call the above controller your URI will look something like this:</p> | |
| <code>www.your-site.com/index.php/products/shoes/123</code> | |
| <p>Each of your sub-folders may contain a default controller which will be | |
| called if the URL contains only the sub-folder. Simply name your default controller as specified in your | |
| <dfn>application/config/routes.php</dfn> file</p> | |
| <p>CodeIgniter also permits you to remap your URIs using its <a href="routing.html">URI Routing</a> feature.</p> | |
| <h2><a name="constructors"></a>Class Constructors</h2> | |
| <p>If you intend to use a constructor in any of your Controllers, you <strong>MUST</strong> place the following line of code in it:</p> | |
| <code>parent::Controller();</code> | |
| <p>The reason this line is necessary is because your local constructor will be overriding the one in the parent controller class so we need to manually call it.</p> | |
| <p>If you are not familiar with constructors, in PHP 4, a <em>constructor</em> is simply a function that has the exact same name as the class:</p> | |
| <code> | |
| <?php<br /> | |
| class <kbd>Blog</kbd> extends Controller {<br /> | |
| <br /> | |
| function <kbd>Blog()</kbd><br /> | |
| {<br /> | |
| <var>parent::Controller();</var><br /> | |
| }<br /> | |
| }<br /> | |
| ?></code> | |
| <p>In PHP 5, constructors use the following syntax:</p> | |
| <code> | |
| <?php<br /> | |
| class <kbd>Blog</kbd> extends Controller {<br /> | |
| <br /> | |
| function <kbd>__construct()</kbd><br /> | |
| {<br /> | |
| <var>parent::Controller();</var><br /> | |
| }<br /> | |
| }<br /> | |
| ?></code> | |
| <p>Constructors are useful if you need to set some default values, or run a default process when your class is instantiated. | |
| Constructors can't return a value, but they can do some default work.</p> | |
| <a name="reserved"></a> | |
| <h2>Reserved Function Names</h2> | |
| <p>Since your controller classes will extend the main application controller you | |
| must be careful not to name your functions identically to the ones used by that class, otherwise your local functions | |
| will override them. The following | |
| is a list of reserved names. Do not name your controller functions any of these:</p> | |
| <ul> | |
| <li>Controller</li> | |
| <li>CI_Base</li> | |
| <li>_ci_initialize</li> | |
| <li>_ci_scaffolding</li> | |
| </ul> | |
| <p><br />If you are running PHP 4 there are some additional reserved names. These ONLY apply if you are running PHP 4.</p> | |
| <ul> | |
| <li>CI_Loader</li> | |
| <li>config</li> | |
| <li>database</li> | |
| <li>dbutil</li> | |
| <li>dbforge</li> | |
| <li>file</li> | |
| <li>helper</li> | |
| <li>helpers</li> | |
| <li>language</li> | |
| <li>library</li> | |
| <li>model</li> | |
| <li>plugin</li> | |
| <li>plugins</li> | |
| <li>scaffolding</li> | |
| <li>script</li> | |
| <li>view</li> | |
| <li>vars</li> | |
| <li>_ci_assign_to_models</li> | |
| <li>_ci_autoloader</li> | |
| <li>_ci_init_class</li> | |
| <li>_ci_init_scaffolding</li> | |
| <li>_ci_is_instance</li> | |
| <li>_ci_load</li> | |
| <li>_ci_load_class</li> | |
| <li>_ci_object_to_array</li> | |
| </ul> | |
| <h2>That's it!</h2> | |
| <p>That, in a nutshell, is all there is to know about controllers.</p> | |
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