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Derek Jones733310d2009-02-11 01:13:43 +0000[diff] [blame]31<td><h1>CodeIgniter User Guide Version 1.7.1</h1></td>
Derek Allard2067d1a2008-11-13 22:59:24 +0000[diff] [blame]32<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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43<a href="http://codeigniter.com/">CodeIgniter Home</a> &nbsp;&#8250;&nbsp;
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45Error Handling
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58<h1>Error Handling</h1>
59
60<p>CodeIgniter lets you build error reporting into your applications using the functions described below.
61In addition, it has an error logging class that permits error and debugging messages to be saved as text files.</p>
62
63<p class="important"><strong>Note:</strong> By default, CodeIgniter displays all PHP errors. You might
64wish to change this behavior once your development is complete. You'll find the <dfn>error_reporting()</dfn>
65function located at the top of your main index.php file. Disabling error reporting will NOT prevent log files
66from being written if there are errors.</p>
67
68<p>Unlike most systems in CodeIgniter, the error functions are simple procedural interfaces that are available
69globally throughout the application. This approach permits error messages to get triggered without having to worry
70about class/function scoping.</p>
71
72<p>The following functions let you generate errors:</p>
73
74<h2>show_error('<var>message</var>')</h2>
75<p>This function will display the error message supplied to it using the following error template:</p>
76<p><dfn>application/errors/</dfn><kbd>error_general.php</kbd></p>
77
78<h2>show_404('<var>page</var>')</h2>
79<p>This function will display the 404 error message supplied to it using the following error template:</p>
80<p><dfn>application/errors/</dfn><kbd>error_404.php</kbd></p>
81
82<p>The function expects the string passed to it to be the file path to the page that isn't found.
83Note that CodeIgniter automatically shows 404 messages if controllers are not found.</p>
84
85
86<h2>log_message('<var>level</var>', '<samp>message</samp>')</h2>
87
88<p>This function lets you write messages to your log files. You must supply one of three "levels"
89in the first parameter, indicating what type of message it is (debug, error, info), with the message
90itself in the second parameter. Example:</p>
91
92<code>
93if ($some_var == "")<br />
94{<br />
95&nbsp;&nbsp;&nbsp;&nbsp;log_message('error', 'Some variable did not contain a value.');<br />
96}<br />
97else<br />
98{<br />
99&nbsp;&nbsp;&nbsp;&nbsp;log_message('debug', 'Some variable was correctly set');<br />
100}<br />
101<br />
102log_message('info', 'The purpose of some variable is to provide some value.');<br />
103</code>
104
105<p>There are three message types:</p>
106
107<ol>
108<li>Error Messages. These are actual errors, such as PHP errors or user errors.</li>
109<li>Debug Messages. These are messages that assist in debugging. For example, if a class has been initialized, you could log this as debugging info.</li>
110<li>Informational Messages. These are the lowest priority messages, simply giving information regarding some process. CodeIgniter doesn't natively generate any info messages but you may want to in your application.</li>
111</ol>
112
113
114<p class="important"><strong>Note:</strong> In order for the log file to actually be written, the
115 "logs" folder must be writable. In addition, you must set the "threshold" for logging.
116You might, for example, only want error messages to be logged, and not the other two types.
117If you set it to zero logging will be disabled.</p>
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