<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <link rel="STYLESHEET" href="modpython.css" type='text/css' /> <link rel="first" href="modpython.html" title='Mod_python Manual' /> <link rel='contents' href='contents.html' title="Contents" /> <link rel='index' href='genindex.html' title='Index' /> <link rel='last' href='about.html' title='About this document...' /> <link rel='help' href='about.html' title='About this document...' /> <link rel="next" href="ssi-output-filter.html" /> <link rel="prev" href="ssi-globals.html" /> <link rel="parent" href="ssi.html" /> <link rel="next" href="ssi-output-filter.html" /> <meta name='aesop' content='information' /> <title>6.5 Conditional Expressions</title> </head> <body> <DIV CLASS="navigation"> <div id='top-navigation-panel' xml:id='top-navigation-panel'> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td class='online-navigation'><a rel="prev" title="6.4 Pre-propulating Globals" href="ssi-globals.html"><img src='previous.png' border='0' height='32' alt='Previous Page' width='32' /></A></td> <td class='online-navigation'><a rel="parent" title="6. 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Server Side Includes</A> <b class="navlabel">Next:</b> <a class="sectref" rel="next" href="ssi-output-filter.html">6.6 Enabling INCLUDES Filter</A> </div> <hr /></div> </DIV> <!--End of Navigation Panel--> <H1><A NAME="SECTION008500000000000000000"></A><A NAME="ssi-conditionals"></A> <BR> 6.5 Conditional Expressions </H1> <P> SSI allows for some programmability in its own right through the use of conditional expressions. The structure of this conditional construct is: <P> <div class="verbatim"><pre> <!--#if expr="test_condition" --> <!--#elif expr="test_condition" --> <!--#else --> <!--#endif --> </pre></div> <P> A test condition can be any sort of logical comparison, either comparing values to one another, or testing the 'truth' of a particular value. <P> The source of variables used in conditional expressions is distinct from the set of global data used by the Python code executed within a page. Instead, the variables are sourced from the <code>subprocess_env</code> table object contained within the request object. The values of these variables can be set from within a page using the SSI 'set' directive, or by a range of other Apache directives within the Apache configuration files such as <code>BrowserMatchNoCase</code> and <code>SetEnvIf</code>. <P> To set these variables from within a mod_python handler, the <code>subprocess_env</code> table object would be manipulated directly through the request object. <P> <div class="verbatim"><pre> from mod_python import apache def fixuphandler(req): debug = req.get_config().get('PythonDebug', '0') req.subprocess_env['DEBUG'] = debug return apache.OK </pre></div> <P> If being done from within Python code contained within the page itself, the request object would first have to be accessed via the filter object. <P> <div class="verbatim"><pre> <!--#python exec=" debug = filter.req.get_config().get('PythonDebug', '0') filter.req.subprocess_env['DEBUG'] = debug " --> <html> <body> <!--#if expr="${DEBUG} != 0" --> DEBUG ENABLED <!--#else --> DEBUG DISABLED <!--#endif --> </body> </html> </pre></div> <P> <DIV CLASS="navigation"> <div class='online-navigation'> <p></p><hr /> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td class='online-navigation'><a rel="prev" title="6.4 Pre-propulating Globals" href="ssi-globals.html"><img src='previous.png' border='0' height='32' alt='Previous Page' width='32' /></A></td> <td class='online-navigation'><a rel="parent" title="6. Server Side Includes" href="ssi.html"><img src='up.png' border='0' height='32' alt='Up One Level' width='32' /></A></td> <td class='online-navigation'><a rel="next" title="6.6 Enabling INCLUDES Filter" href="ssi-output-filter.html"><img src='next.png' border='0' height='32' alt='Next Page' width='32' /></A></td> <td align="center" width="100%">Mod_python Manual</td> <td class='online-navigation'><a rel="contents" title="Table of Contents" href="contents.html"><img src='contents.png' border='0' height='32' alt='Contents' width='32' /></A></td> <td class='online-navigation'><img src='blank.png' border='0' height='32' alt='' width='32' /></td> <td class='online-navigation'><a rel="index" title="Index" href="genindex.html"><img src='index.png' border='0' height='32' alt='Index' width='32' /></A></td> </tr></table> <div class='online-navigation'> <b class="navlabel">Previous:</b> <a class="sectref" rel="prev" href="ssi-globals.html">6.4 Pre-propulating Globals</A> <b class="navlabel">Up:</b> <a class="sectref" rel="parent" href="ssi.html">6. Server Side Includes</A> <b class="navlabel">Next:</b> <a class="sectref" rel="next" href="ssi-output-filter.html">6.6 Enabling INCLUDES Filter</A> </div> </div> <hr /> <span class="release-info">Release 3.3.1, documentation updated on January 29, 2007.</span> </DIV> <!--End of Navigation Panel--> </BODY> </HTML>