| admin | b0dd10f | 2006-08-25 17:25:49 +0000 | [diff] [blame] | 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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| 33 | <div id="masthead">
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| 34 | <table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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| 35 | <tr>
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| 36 | <td><h1>Code Igniter User Guide Version 1.4.0</h1></td>
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| 37 | <td id="breadcrumb_right"><a href="../toc.html">Full Table of Contents</a></td>
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| 38 | </tr>
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| 42 |
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| 45 | <table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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| 46 | <tr>
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| 47 | <td id="breadcrumb">
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| 48 | <a href="http://www.codeigniter.com/">Code Igniter Home</a> ›
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| 49 | <a href="../index.html">User Guide Home</a> ›
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| 50 | Controllers
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| 51 | </td>
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| 58 |
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| 59 |
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| 60 | <!-- START CONTENT -->
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| 61 | <div id="content">
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| 62 |
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| 63 | <h1>Controllers</h1>
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| 64 |
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| 65 | <p>Controllers are the heart of your application, as they determine how HTTP requests should be handled.</p>
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| 66 |
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| 67 |
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| 68 | <ul>
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| 69 | <li><a href="#what">What is a Controller?</a></li>
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| 70 | <li><a href="#hello">Hello World</a></li>
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| 71 | <li><a href="#functions">Functions</a></li>
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| admin | 1cf89aa | 2006-09-03 18:24:39 +0000 | [diff] [blame^] | 72 | <li><a href="#remapping">Remapping Function Calls</a></li>
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| admin | b0dd10f | 2006-08-25 17:25:49 +0000 | [diff] [blame] | 73 | <li><a href="#private">Private Functions</a></li>
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| 74 | <li><a href="#default">Defining a Default Controller</a></li>
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| admin | b071bb5 | 2006-08-26 19:28:37 +0000 | [diff] [blame] | 75 | <li><a href="#subfolders">Organizing Controllers into Sub-folders</a></li>
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| admin | b0dd10f | 2006-08-25 17:25:49 +0000 | [diff] [blame] | 76 | <li><a href="#constructors">Class Constructors</a></li>
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| 77 | <li><a href="#reserved">Reserved Function Names</a></li>
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| 78 | </ul>
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| 79 |
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| 80 |
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| 81 | <a name="what"></a>
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| 82 | <h2>What is a Controller?</h2>
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| 83 |
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| 84 | <p><dfn>A Controller is simply a class file that is named in a way that can be associated with a URI.</dfn></p>
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| 85 |
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| 86 | <p>Consider this URI:</p>
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| 87 |
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| 88 | <code>www.your-site.com/index.php/<var>blog</var>/</code>
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| 89 |
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| 90 | <p>In the above example, Code Igniter would attempt to find a controller named <dfn>blog.php</dfn> and load it.</p>
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| 91 |
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| 92 | <p><strong>When a controller's name matches the first segment of a URI, it will be loaded.</strong></p>
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| 93 |
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| 94 | <a name="hello"></a>
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| 95 | <h2>Let's try it: Hello World!</h2>
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| 96 |
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| 97 | <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>
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| 98 |
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| 99 |
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| 100 | <textarea class="textarea" style="width:100%" cols="50" rows="10">
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| 101 | <?php
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| 102 | class Blog extends Controller {
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| 103 |
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| 104 | function index()
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| 105 | {
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| 106 | echo 'Hello World!';
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| 107 | }
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| 108 | }
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| 109 | ?>
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| 110 | </textarea>
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| 111 |
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| 112 |
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| 113 |
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| 114 | <p>Then save the file to your <dfn>application/controllers/</dfn> folder.</p>
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| 115 |
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| 116 | <p>Now visit the your site using a URL similar to this:</p>
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| 117 |
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| 118 | <code>www.your-site.com/index.php/<var>blog</var>/</code>
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| 119 |
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| 120 | <p>If you did it right, you should see <samp>Hello World!</samp>.</p>
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| 121 |
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| 122 | <p>Note: Class names must start with an uppercase letter. In other words, this is valid:
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| 123 |
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| 124 | <code><?php<br />
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| 125 | class <var>Blog</var> extends Controller {<br />
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| 126 | <br />
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| 127 | }<br />
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| 128 | ?></code>
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| 129 |
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| 130 | <p>This is <strong>not</strong> valid:</p>
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| 131 |
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| 132 | <code><?php<br />
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| 133 | class <var>blog</var> extends Controller {<br />
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| 134 | <br />
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| 135 | }<br />
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| 136 | ?></code>
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| 137 |
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| 138 | <p>Also, always make sure your controller <dfn>extends</dfn> the parent controller class so that it can inherit all its functions.</p>
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| 139 |
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| 140 |
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| 141 |
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| 142 | <a name="functions"></a>
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| 143 | <h2>Functions</h2>
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| 144 |
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| 145 | <p>In the above example the function name is <dfn>index()</dfn>. The "index" function is always loaded by default if the
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| 146 | <strong>second segment</strong> of the URI is empty. Another way to show your "Hello World" message would be this:</p>
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| 147 |
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| 148 | <code>www.your-site.com/index.php/<var>blog</var>/<samp>index</samp>/</code>
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| 149 |
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| 150 | <p><strong>The second segment of the URI determines which function in the controller gets called.</strong></p>
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| 151 |
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| 152 | <p>Let's try it. Add a new function to your controller:</p>
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| 153 |
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| 154 |
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| 155 | <textarea class="textarea" style="width:100%" cols="50" rows="15">
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| 156 | <?php
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| 157 | class Blog extends Controller {
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| 158 |
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| 159 | function index()
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| 160 | {
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| 161 | echo 'Hello World!';
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| 162 | }
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| 163 |
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| 164 | function comments()
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| 165 | {
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| 166 | echo 'Look at this!';
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| 167 | }
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| 168 | }
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| 169 | ?>
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| 170 | </textarea>
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| 171 |
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| 172 | <p>Now load the following URL to see the <dfn>comment</dfn> function:</p>
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| 173 |
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| 174 | <code>www.your-site.com/index.php/<var>blog</var>/<samp>comments</samp>/</code>
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| 175 |
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| 176 | <p>You should see your new message.</p>
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| 177 |
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| admin | 1cf89aa | 2006-09-03 18:24:39 +0000 | [diff] [blame^] | 178 |
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| 179 | <a name="remapping"></a>
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| 180 | <h2>Remapping Function Calls</h2>
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| 181 |
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| 182 | <p>As noted above, the second segment of the URI typically determines which function in the controller gets called.
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| 183 | Code Igniter permits you to override this behavior through the use of the <kbd>_remap()</kbd> function:</p>
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| 184 |
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| 185 | <code>function _remap()<br />
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| 186 | {<br />
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| 187 | // Some code here...<br />
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| 188 | }</code>
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| 189 |
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| 190 | <p class="important"><strong>Important:</strong> If your controller contains a function named <kbd>_remap()</kbd>, it will <strong>always</strong>
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| 191 | get called regardless of what your URI contains. It overrides the normal behavior in which the URI determines which function is called,
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| 192 | allowing you to define your own function routing rules.</p>
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| 193 |
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| 194 | <p>The overriden function call (typically the second segment of the URI) will be passed as a parameter the <kbd>_remap()</kbd> function:</p>
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| 195 |
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| 196 | <code>function _remap(<var>$method</var>)<br />
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| 197 | {<br />
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| 198 | if ($method == 'some_method')<br />
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| 199 | {<br />
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| 200 | $this->$method();<br />
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| 201 | }<br />
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| 202 | else<br />
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| 203 | {<br />
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| 204 | $this->default_method();<br />
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| 205 | }<br />
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| 206 | }</code>
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| 207 |
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| 208 |
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| 209 |
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| 210 |
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| admin | b0dd10f | 2006-08-25 17:25:49 +0000 | [diff] [blame] | 211 | <a name="private"></a>
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| 212 | <h2>Private Functions</h2>
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| 213 |
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| admin | 1cf89aa | 2006-09-03 18:24:39 +0000 | [diff] [blame^] | 214 | <p>In some cases you may want certain functions hidden from public access. To make a function private, simply add an
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| admin | b0dd10f | 2006-08-25 17:25:49 +0000 | [diff] [blame] | 215 | 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>
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| 216 |
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| 217 | <code>
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| 218 | function _utility()<br />
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| 219 | {<br />
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| 220 | // some code<br />
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| 221 | }</code>
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| 222 |
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| 223 | <p>Trying to access it via the URL, like this, will not work:</p>
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| 224 |
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| 225 | <code>www.your-site.com/index.php/<var>blog</var>/<samp>_utility</samp>/</code>
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| 226 |
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| 227 |
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| 228 |
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| 229 | <a name="default"></a>
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| 230 | <h2>Defining a Default Controller</h2>
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| 231 |
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| 232 | <p>Code Igniter can be told to load a default controller when a URI is not present,
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| 233 | as will be the case when only your site root URL is requested. To specify a default controller, open
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| 234 | your <dfn>application/config/routes.php</dfn> file and set this variable:</p>
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| 235 |
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| 236 | <code>$route['default_controller'] = '<var>Blog</var>';</code>
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| 237 |
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| 238 | <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
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| 239 | specifying any URI segments you'll see your Hello World message by default.</p>
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| 240 |
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| 241 |
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| admin | b071bb5 | 2006-08-26 19:28:37 +0000 | [diff] [blame] | 242 | <a name="subfolders"></a>
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| 243 | <h2>Organizing Your Controllers into Sub-folders</h2>
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| 244 |
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| 245 | <p>If you are building a large application you might find it convenient to organize your controllers into sub-folders. Code Igniter permits you to do this.</p>
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| 246 |
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| 247 | <p>Simply create folders within your <dfn>application/controllers</dfn> directory and place your controller classes within them.</p>
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| 248 |
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| admin | 1082bdd | 2006-08-27 19:32:02 +0000 | [diff] [blame] | 249 | <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
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| admin | b071bb5 | 2006-08-26 19:28:37 +0000 | [diff] [blame] | 250 | located here:</p>
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| 251 |
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| 252 | <code>application/controllers/<kbd>products</kbd>/shoes.php</code>
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| 253 |
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| 254 | <p>To call the above controller your URI will look something like this:</p>
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| 255 |
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| 256 | <code>www.your-site.com/index.php/products/shoes/123</code>
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| 257 |
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| 258 | <p>Code Igniter also permits you to remap your URIs using its <a href="routing.html">URI Routing</a> feature.
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| 259 |
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| 260 |
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| admin | b0dd10f | 2006-08-25 17:25:49 +0000 | [diff] [blame] | 261 | <a name="constructors"></a>
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| 262 | <h2>Class Constructors</h2>
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| 263 |
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| 264 |
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| 265 | <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>
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| 266 |
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| 267 | <code>parent::Controller();</code>
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| 268 |
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| 269 | <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>
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| 270 |
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| 271 |
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| 272 | <p>If you are not familliar with constructors, in PHP 4, a <em>constructor</em> is simply a function that has the exact same name as the class:</p>
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| 273 |
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| 274 | <code>
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| 275 | <?php<br />
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| 276 | class <kbd>Blog</kbd> extends Controller {<br />
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| 277 | <br />
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| 278 | function <kbd>Blog()</kbd><br />
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| 279 | {<br />
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| 280 | <var>parent::Controller();</var><br />
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| 281 | }<br />
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| 282 | }<br />
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| 283 | ?></code>
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| 284 |
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| 285 | <p>In PHP 5, constructors use the following syntax:</p>
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| 286 |
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| 287 | <code>
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| 288 | <?php<br />
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| 289 | class <kbd>Blog</kbd> extends Controller {<br />
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| 290 | <br />
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| 291 | function <kbd>__construct()</kbd><br />
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| 292 | {<br />
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| 293 | <var>parent::Controller();</var><br />
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| 294 | }<br />
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| 295 | }<br />
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| 296 | ?></code>
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| 297 |
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| 298 | <p>Constructors are useful if you need to set some default values, or run a default process when your class is instantiated.
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| 299 | Constructors can't return a value, but they can do some default work.</p>
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| 300 |
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| 301 | <a name="reserved"></a>
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| 302 | <h2>Reserved Function Names</h2>
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| 303 |
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| 304 | <p>Since your controller classes will extend the main application controller you
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| 305 | must be careful not to name your functions identically to the ones used by that class, otherwise your local functions
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| 306 | will override them. The following
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| 307 | is a list of reserved names. Do not name your controller functions any of these:</p>
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| 308 |
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| 309 | <ul>
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| 310 | <li>Controller</li>
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| 311 | <li>CI_Base</li>
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| 312 | <li>_ci_autoload</li>
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| 313 | <li>_ci_autoloader</li>
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| 314 | <li>_ci_assign_core</li>
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| 315 | <li>_ci_initialize</li>
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| 316 | <li>_ci_init_database</li>
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| 317 | <li>_ci_init_scaffolding</li>
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| 318 | <li>_ci_is_loaded</li>
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| 319 | <li>_ci_load</li>
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| 320 | <li>_ci_scaffolding</li>
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| 321 | <li>_ci_set_view_path</li>
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| 322 | </ul>
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| 323 |
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| 324 | <p><br />If you are running PHP 4 there are some additional reserved names. These ONLY apply if you are running PHP 4.</p>
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| 325 |
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| 326 | <ul>
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| 327 | <li>CI_Loader</li>
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| 328 | <li>config</li>
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| 329 | <li>database</li>
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| 330 | <li>file</li>
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| 331 | <li>helper</li>
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| 332 | <li>helpers</li>
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| 333 | <li>language</li>
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| 334 | <li>library</li>
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| 335 | <li>plugin</li>
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| 336 | <li>plugins</li>
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| 337 | <li>scaffolding</li>
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| 338 | <li>script</li>
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| 339 | <li>view</li>
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| 340 | <li>vars</li>
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| 341 | </ul>
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| 342 |
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| 343 |
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| 344 |
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| 345 |
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| 346 |
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| 347 |
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| 348 | <h2>That's it!</h2>
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| 349 |
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| 350 | <p>That, in a nutshell, is all there is to know about controllers.</p>
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| 351 |
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| 352 |
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| 353 |
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| 354 | </div>
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| 355 | <!-- END CONTENT -->
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| 356 |
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| 367 | <p><a href="http://www.codeigniter.com">Code Igniter</a> · Copyright © 2006 · <a href="http://www.pmachine.com">pMachine, Inc.</a></p>
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