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authorDerek Jones <derek.jones@ellislab.com>2011-10-05 20:34:52 +0200
committerDerek Jones <derek.jones@ellislab.com>2011-10-05 20:34:52 +0200
commit8ede1a2ecbb62577afd32996956c5feaf7ddf9b6 (patch)
tree2e960ec3b416b477f40bb546371f2d486f4a22f0 /user_guide/general/controllers.html
parentd1ecd5cd4ae6ab5d37df9fbda14b93977b9e743c (diff)
replacing the old HTML user guide with a Sphinx-managed user guide
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-<tr>
-<td><h1>CodeIgniter User Guide Version 2.0.3</h1></td>
-<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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-<a href="http://codeigniter.com/">CodeIgniter Home</a> &nbsp;&#8250;&nbsp;
-<a href="../index.html">User Guide Home</a> &nbsp;&#8250;&nbsp;
-Controllers
-</td>
-<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide&nbsp; <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" />&nbsp;<input type="submit" class="submit" name="sa" value="Go" /></form></td>
-</tr>
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-
-<br clear="all" />
-
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-<!-- START CONTENT -->
-<div id="content">
-
-<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>example.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:&nbsp; 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">
-&lt;?php
-class Blog extends CI_Controller {
-
- public function index()
- {
- echo 'Hello World!';
- }
-}
-?&gt;
-</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>example.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>&lt;?php<br />
-class <var>Blog</var> extends CI_Controller {<br />
-<br />
-}<br />
-?&gt;</code>
-
-<p>This is <strong>not</strong> valid:</p>
-
-<code>&lt;?php<br />
-class <var>blog</var> extends CI_Controller {<br />
-<br />
-}<br />
-?&gt;</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>example.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">
-&lt;?php
-class Blog extends CI_Controller {
-
- public function index()
- {
- echo 'Hello World!';
- }
-
- public function comments()
- {
- echo 'Look at this!';
- }
-}
-?&gt;
-</textarea>
-
-<p>Now load the following URL to see the <dfn>comment</dfn> function:</p>
-
-<code>example.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>example.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>
-&lt;?php<br />
-class Products extends CI_Controller {<br />
-<br />
-&nbsp;&nbsp;&nbsp;&nbsp;public function shoes($sandals, $id)<br />
-&nbsp;&nbsp;&nbsp;&nbsp;{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo $sandals;<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo $id;<br />
-&nbsp;&nbsp;&nbsp;&nbsp;}<br />
-}<br />
-?&gt;
-</code>
-
-<p class="important"><strong>Important:</strong>&nbsp; If you are using the <a href="routing.html">URI Routing</a> feature, the segments
-passed to your function will be the re-routed ones.</p>
-
-
-<a name="default"></a>
-<h2>Defining a Default Controller</h2>
-
-<p>CodeIgniter can be told to load a default controller when a URI is not present,
-as will be the case when only your site root URL is requested. To specify a default controller, open
-your <dfn>application/config/routes.php</dfn> file and set this variable:</p>
-
-<code>$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>public function _remap()<br />
-{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;// Some code here...<br />
-}</code>
-
-<p class="important"><strong>Important:</strong>&nbsp; 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 to the <kbd>_remap()</kbd> function:</p>
-
-<code>public function _remap(<var>$method</var>)<br />
-{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;if ($method == 'some_method')<br />
-&nbsp;&nbsp;&nbsp;&nbsp;{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;$this->$method();<br />
-&nbsp;&nbsp;&nbsp;&nbsp;}<br />
-&nbsp;&nbsp;&nbsp;&nbsp;else<br />
-&nbsp;&nbsp;&nbsp;&nbsp;{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;$this->default_method();<br />
-&nbsp;&nbsp;&nbsp;&nbsp;}<br />
-}</code>
-
-<p>Any extra segments after the method name are passed into <kbd>_remap()</kbd> as an optional second parameter. This array can be used in combination with PHP's <a href="http://php.net/call_user_func_array">call_user_func_array</a> to emulate CodeIgniter's default behavior.</p>
-
-<code>public function _remap($method, $params = array())<br />
-{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;$method = 'process_'.$method;<br />
-&nbsp;&nbsp;&nbsp;&nbsp;if (method_exists($this, $method))<br />
-&nbsp;&nbsp;&nbsp;&nbsp;{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return call_user_func_array(array($this, $method), $params);<br />
-&nbsp;&nbsp;&nbsp;&nbsp;}<br />
-&nbsp;&nbsp;&nbsp;&nbsp;show_404();<br />
-}</code>
-
-
-<a name="output"></a>
-<h2>Processing Output</h2>
-
-<p>CodeIgniter has an output class that takes care of sending your final rendered data to the web browser automatically. More information on this can be found in the
-<a href="views.html">Views</a> and <a href="../libraries/output.html">Output class</a> pages. In some cases, however, you might want to
-post-process the finalized data in some way and send it to the browser yourself. CodeIgniter permits you to
-add a function named <dfn>_output()</dfn> to your controller that will receive the finalized output data.</p>
-
-<p><strong>Important:</strong>&nbsp; If your controller contains a function named <kbd>_output()</kbd>, it will <strong>always</strong>
-be called by the output class instead of echoing the finalized data directly. The first parameter of the function will contain the finalized output.</p>
-
-<p>Here is an example:</p>
-
-<code>
-public function _output($output)<br />
-{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;echo $output;<br />
-}</code>
-
-<p class="important">Please note that your <dfn>_output()</dfn> function will receive the data in its finalized state. Benchmark and memory usage data will be rendered,
-cache files written (if you have caching enabled), and headers will be sent (if you use that <a href="../libraries/output.html">feature</a>)
-before it is handed off to the _output() function.<br />
-<br />
-To have your controller's output cached properly, its <dfn>_output()</dfn> method can use:<br />
-
-<code>if ($this-&gt;output-&gt;cache_expiration &gt; 0)<br />
-{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;$this-&gt;output-&gt;_write_cache($output);<br />
-}</code>
-
-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>
-private function _utility()<br />
-{<br />
-&nbsp;&nbsp;// some code<br />
-}</code>
-
-<p>Trying to access it via the URL, like this, will not work:</p>
-
-<code>example.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>&nbsp; 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>example.com/index.php/products/shoes/show/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::__construct();</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>
-
-<code>
-&lt;?php<br />
-class <kbd>Blog</kbd> extends CI_Controller {<br />
-<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;public function <kbd>__construct()</kbd><br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<var>parent::__construct();</var><br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Your own constructor code<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<br />
-}<br />
-?&gt;</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. See <a href="reserved_names.html">Reserved Names</a> for a full list.</p>
-
-<h2>That's it!</h2>
-
-<p>That, in a nutshell, is all there is to know about controllers.</p>
-
-
-
-</div>
-<!-- END CONTENT -->
-
-
-<div id="footer">
-<p>
-Previous Topic:&nbsp;&nbsp;<a href="urls.html">CodeIgniter URLs</a>
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-Next Topic:&nbsp;&nbsp;<a href="reserved_names.html">Reserved Names</a></p>
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