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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Strict//EN"> <html> <head> <title>Template::FAQ</title> <link rel="stylesheet" type="text/css" href="../css/blue.css" title="Clear Blue"> <link rel="alternate stylesheet" type="text/css" href="../css/orange.css" title="Clear Orange"> <link rel="alternate stylesheet" type="text/css" href="../css/green.css" title="Clear Green"> <link rel="alternate stylesheet" type="text/css" href="../css/purple.css" title="Clear Purple"> <link rel="alternate stylesheet" type="text/css" href="../css/grey.css" title="Clear Grey"> <link rel="alternate stylesheet" type="text/css" href="../css/print.css" title="Print"> <!--[if IE 6]> <link rel="stylesheet" type="text/css" href="../css/ie6.css" /> <![endif]--> <!--[if IE 7]> <link rel="stylesheet" type="text/css" href="../css/ie7.css" /> <![endif]--> <link rel="stylesheet" type="text/css" href="../css/print.css" media="print"> <script type="text/javascript" src="../js/tt2.js"></script> <meta http-equiv="Content-Type" content="text/html;charset=utf-8"> <meta name="author" content="Andy Wardley"> </head> <body id="body"> <div id="layout"> <div id="header"> <a href="../index.html" id="logo" alt="" title="Click for the Home Page"><span class="alt">TT2 Home Page</span></a> <ul id="trail"> <li class="last"><a href="../faq/index.html">FAQ</a></li> </ul> <div class="controls"> <a href="#" class="menu show" onclick="widescreen_off(); return false" title="Show Menu"> <span class="about">Click to view the menu. It's very nice.</span> </a> <a href="#" class="menu hide" onclick="widescreen_on(); return false" title="Hide Menu"> <span class="about">Click to hide the menu and go all widescreen!</span> </a> <div class="pager"> <a href="../tutorial/index.html" title="Template::Tutorial" class="go back">Back<span class="about"><h4>Template::Tutorial</h4>Template Toolkit Tutorials</span></a> <a href="../index.html" title="Template::Toolkit" class="go up">Up<span class="about"><h4>Template::Toolkit</h4>Template Processing System</span></a> <span class="go next">Next<span class="about">Hello, I'm a talking badger.</span></span> </div> </div> <h1 class="headline">Template::FAQ</h1> <h2 class="subhead">Frequently Asked Questions about the Template Toolkit</h1> </div> <div id="page"> <div id="sidebar"> <a href="../index.html" id="logo"></a> <div id="menu"> <ul class="menu"> <li class="l0 first"><a href="../manual/index.html">Manual</a></li> <li class="l0"><a href="../modules/index.html">Modules</a></li> <li class="l0"><a href="../tools/index.html">Tools</a></li> <li class="l0"><a href="../tutorial/index.html">Tutorial</a></li> <li class="l0 last"><a href="../faq/index.html" class="warm">FAQ</a></li> </ul> <div class="foot"></div> </div> </div> <div id="content"> <div class="section"> <div class="head"> <h1 id="contents" onclick="switch_section(this)" title="Click title to show/hide section content.">Contents</h1> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <ul class="toc"> <li class=""><a href="#Template_Toolkit_Language">Template Toolkit Language</a></li> <li class="sub"><a href="#section_Why_doesn_t_a_b_IF_c_work_as_expected_">Why doesn't [% a = b IF c %] work as expected?</a></li> <li class="sub"><a href="#section_If_I_m_using_TT_to_write_out_a_TT_template_is_there_a_good_way_to_escape_and_">If I'm using TT to write out a TT template, is there a good way to escape [% and %]?</a></li> <li class="sub"><a href="#section_How_do_I_iterate_over_a_hash_">How do I iterate over a hash?</a></li> <li class=""><a href="#Plugins">Plugins</a></li> <li class="sub"><a href="#section_How_do_I_get_the_Table_plugin_to_order_data_across_rather_than_down_">How do I get the Table plugin to order data across rather than down?</a></li> <li class="sub"><a href="#section_Accessing_Cookies">Accessing Cookies</a></li> <li class=""><a href="#Extending_the_Template_Toolkit">Extending the Template Toolkit</a></li> <li class="sub"><a href="#section_Can_I_serve_templates_from_a_database_">Can I serve templates from a database?</a></li> <li class="sub"><a href="#section_Can_I_fetch_templates_via_http_">Can I fetch templates via http?</a></li> <li class=""><a href="#Miscellaneous">Miscellaneous</a></li> <li class="sub"><a href="#section_How_can_I_find_out_the_name_of_the_main_template_being_processed_">How can I find out the name of the main template being processed?</a></li> <li class="sub"><a href="#section_How_can_I_find_out_the_name_of_the_current_template_being_processed_">How can I find out the name of the current template being processed?</a></li> <li class="sub"><a href="#section_How_do_I_print_the_modification_time_of_the_template_or_component_">How do I print the modification time of the template or component?</a></li> <li class="sub"><a href="#section_How_can_I_configure_variables_on_a_per_request_basis_">How can I configure variables on a per-request basis?</a></li> <li class="sub"><a href="#section_Why_do_I_get_rubbish_for_my_utf_8_templates_">Why do I get rubbish for my utf-8 templates?</a></li> <li class=""><a href="#Questions_About_This_FAQ">Questions About This FAQ</a></li> <li class="sub"><a href="#section_Why_is_this_FAQ_so_short_">Why is this FAQ so short?</a></li> <li class="sub"><a href="#section_Can_I_help_">Can I help?</a></li> </ul> </div> </div> <div class="pod"> <div class="section"> <div class="head"> <h1 id="Template_Toolkit_Language" onclick="switch_section(this)" title="Click title to show/hide section content.">Template Toolkit Language</h1> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <div class="subsection"> <div class="head"> <h2 id="section_Why_doesn_t_a_b_IF_c_work_as_expected_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Why doesn't [% a = b IF c %] work as expected?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> There's a limitation in the TT2 parser which means that the following code doesn't work as you might expect: </p> <pre><span class="tt">[% a = b IF c %]</span></pre> <p> The parser interprets it as an attempt to set <code>a</code> to the result of <code>b IF c</code>, like this: </p> <pre><span class="tt">[% a = (b IF c) %]</span></pre> <p> If you want to set <code>a = b</code> only if <code>c</code> is true, then do this instead: </p> <pre><span class="tt">[% SET a = b IF c %]</span></pre> <p> The explicit <code>SET</code> keyword gives the parser the clue it needs to do the right thing. </p> <p> NOTE: this will be fixed in TT3 </p> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_If_I_m_using_TT_to_write_out_a_TT_template_is_there_a_good_way_to_escape_and_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">If I'm using TT to write out a TT template, is there a good way to escape [% and %]?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> You can do something like this: </p> <pre><span class="tt">[% stag = "[\%" etag = "%\]" %]</span></pre> <p> and then: </p> <pre><span class="tt">[% stag; 'hello'; etag %]</span></pre> <p> Or you can use the <code>TAGS</code> directive, like so: </p> <pre><span class="tt">[% TAGS [- -] %]</span> [- INCLUDE foo -] # is a directive <span class="tt">[% INCLUDE foo %]</span> # not a directive</pre> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_How_do_I_iterate_over_a_hash_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">How do I iterate over a hash?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> This is covered in the <a href="../manual/VMethods.html">Template::Manual::VMethods</a> section of the manual. A list of all the keys that are in the hash can be obtained with the <code>keys</code> virtual method. You can then iterate over that list and by looking up each key in turn get the value. </p> <pre><span class="tt">[% FOREACH key = product.keys %]</span> <span class="tt">[% key %]</span> => <span class="tt">[% product.$key %]</span> <span class="tt">[% END %]</span></pre> </div> </div> </div> </div> <div class="section"> <div class="head"> <h1 id="Plugins" onclick="switch_section(this)" title="Click title to show/hide section content.">Plugins</h1> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <div class="subsection"> <div class="head"> <h2 id="section_How_do_I_get_the_Table_plugin_to_order_data_across_rather_than_down_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">How do I get the Table plugin to order data across rather than down?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> Order the data into rows: </p> <pre>Steve Karen Jeff Brooklyn Nantucket Fairfax NY MA VA <span class="tt">[% USE table(data, rows=3) %]</span></pre> <p> Then ask for each column </p> <pre><span class="tt">[% FOREACH column = table.cols %]</span></pre> <p> And then print each item in the column going across the output rows </p> <pre><span class="tt">[% FOREACH item = column %]</span> <td><span class="tt">[% item %]</span></td> <span class="tt">[% END %]</span></pre> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_Accessing_Cookies" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Accessing Cookies</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> Jeff Boes <jboes@nexcerpt.com> asks: </p> <pre>Does anyone have a quick-n-dirty approach to accessing cookies from templates?</pre> <p> Jonas Liljegren answers: </p> <pre><span class="tt">[% USE CGI %]</span> <p>The value is <span class="tt">[% CGI.cookie('cookie_name') | html %]</span></pre> </div> </div> </div> </div> <div class="section"> <div class="head"> <h1 id="Extending_the_Template_Toolkit" onclick="switch_section(this)" title="Click title to show/hide section content.">Extending the Template Toolkit</h1> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <div class="subsection"> <div class="head"> <h2 id="section_Can_I_serve_templates_from_a_database_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Can I serve templates from a database?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> Short answer: yes, Chris Nandor has done this for Slash. You need to subclass <a href="../modules/Template/Provider.html">Template::Provider</a>. See the mailing list archives for further info. </p> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_Can_I_fetch_templates_via_http_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Can I fetch templates via http?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> To do the job properly, you should subclass <a href="../modules/Template/Provider.html">Template::Provider</a> to <code>Template::Provider::HTTP</code> and use a <code>PREFIX_MAP</code> option to bind the <code>http</code> template prefix to that particular provider (you may want to go digging around in the <i>Changes</i> file around version 2.01 for more info on <code>PREFIX_MAP</code> - it may not be properly documented anywhere else...yet!). e.g. </p> <pre>use Template::Provider::HTTP; my $file = Template::Provider( INCLUDE_PATH => [...] ); my $http = Template::Provider::HTTP->new(...); my $tt2 = Template->new({ LOAD_TEMPLATES => [ $file, $http ], PREFIX_MAP => { file => '0', # file:foo.html http => '1', # http:foo.html default => '0', # foo.html => file:foo.html } });</pre> <p> Now a template specified as: </p> <pre><span class="tt">[% INCLUDE foo %]</span></pre> <p> will be served by the 'file' provider (the default). Otherwise you can explicitly add a prefix: </p> <pre><span class="tt">[% INCLUDE file:foo.html %]</span> <span class="tt">[% INCLUDE http:foo.html %]</span> <span class="tt">[% INCLUDE http://www.xyz.com/tt2/header.tt2 %]</span></pre> <p> This same principal can be used to create a DBI template provider. e.g. </p> <pre><span class="tt">[% INCLUDE dbi:foo.html %]</span></pre> <p> Alas, we don't yet have a DBI provider as part of the Template Toolkit. There has been some talk on the mailing list about efforts to develop DBI and/or HTTP providers but as yet no-one has stepped forward to take up the challenge... </p> <p> In the mean time, Craig Barrat's post from the mailing list has some useful pointers on how to achieve this using existing modules. See <a href="http://tt2.org/pipermail/templates/2001-May/000954.html">http://tt2.org/pipermail/templates/2001-May/000954.html</a> </p> </div> </div> </div> </div> <div class="section"> <div class="head"> <h1 id="Miscellaneous" onclick="switch_section(this)" title="Click title to show/hide section content.">Miscellaneous</h1> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <div class="subsection"> <div class="head"> <h2 id="section_How_can_I_find_out_the_name_of_the_main_template_being_processed_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">How can I find out the name of the main template being processed?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> The <code>template</code> variable contains a reference to the Template::Document object for the main template you're processing (i.e. the one provided as the first argument to the Template process() method). The <code>name</code> method returns its name. </p> <pre><span class="tt">[% template.name %]</span> # e.g. index.html</pre> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_How_can_I_find_out_the_name_of_the_current_template_being_processed_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">How can I find out the name of the current template being processed?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> The <code>template</code> variable always references the <i>main</i> template being processed. So even if you call [% INCLUDE header %], and that calls [% INCLUDE menu %], the <code>template</code> variable will be unchanged. </p> <p> index.html: </p> <pre><span class="tt">[% template.name %]</span> # index.html <span class="tt">[% INCLUDE header %]</span></pre> <p> header: </p> <pre><span class="tt">[% template.name %]</span> # index.html <span class="tt">[% INCLUDE menu %]</span></pre> <p> menu: </p> <pre><span class="tt">[% template.name %]</span> # index.html</pre> <p> In constrast, the <code>component</code> variable always references the <i>current</i> template being processed. </p> <p> index.html </p> <pre><span class="tt">[% component.name %]</span> # index.html <span class="tt">[% INCLUDE header %]</span></pre> <p> header: </p> <pre><span class="tt">[% component.name %]</span> # header <span class="tt">[% INCLUDE menu %]</span></pre> <p> menu: </p> <pre><span class="tt">[% component.name %]</span> # menu</pre> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_How_do_I_print_the_modification_time_of_the_template_or_component_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">How do I print the modification time of the template or component?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> The <code>template</code> and <code>component</code> variables reference the main template and the current template being processed (see previous questions). The <code>modtime</code> method returns the modification time of the corresponding template file as a number of seconds since the Unix epoch (00:00:00 GMT 1st January 1970). </p> <p> This number doesn't mean much to anyone (except perhaps serious Unix geeks) so you'll probably want to use the Date plugin to format it for human consumption. </p> <pre><span class="tt">[% USE Date %]</span> <span class="tt">[% template.name %]</span> last modified <span class="tt">[% Date.format(template.modtime) %]</span></pre> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_How_can_I_configure_variables_on_a_per_request_basis_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">How can I configure variables on a per-request basis?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> One easy way to achieve this is to define a single <code>PRE_PROCESS</code> template which loads in other configuration files based on variables defined or other conditions. </p> <p> For example, my setup usually looks something like this: </p> <pre>PRE_PROCESS => 'config/main'</pre> <p> config/main: </p> <pre><span class="tt">[% DEFAULT style = 'text' section = template.section or 'home'; PROCESS config/site + config/urls + config/macros + "config/style/$style" + "config/section/$section" + ... %]</span></pre> <p> This allows me to set a single 'style' variable to control which config file gets pre-processed to set my various style options (colours, img paths, etc). For example: </p> <p> config/style/basic: </p> <pre><span class="tt">[% style = { name = style # save existing 'style' var as 'style.name' # define various other style variables.... col = { back => '#ffffff' text => '#000000' # ...etc... } logo = { # ...etc... } # ...etc... } %]</span></pre> <p> Each source template can declare which section it's in via a META directive: </p> <pre><span class="tt">[% META title = 'General Information' section = 'info' %]</span> ...</pre> <p> This controls which section configuration file gets loaded to set various other variables for defining the section title, menu, etc. </p> <p> config/section/info: </p> <pre><span class="tt">[% section = { name = section # save 'section' var as 'section.name' title = 'Information' menu = [ ... ] # ...etc... } %]</span></pre> <p> This illustrates the basic principal but you can extend it to perform pretty much any kind of per-document initialisation that you require. </p> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_Why_do_I_get_rubbish_for_my_utf_8_templates_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Why do I get rubbish for my utf-8 templates?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> First of all, make sure that your template files define a Byte Order Mark <a href="http://en.wikipedia.org/wiki/Byte_Order_Mark">http://en.wikipedia.org/wiki/Byte_Order_Mark</a> </p> <p> If you for some reason don't want to add BOM to your templates, you can force Template to use a particular encoding (e.g. <code>utf8</code>) for your templates with the <code>ENCODING</code> option. </p> <pre>my $template = Template->new({ ENCODING => 'utf8' });</pre> </div> </div> </div> </div> <div class="section"> <div class="head"> <h1 id="Questions_About_This_FAQ" onclick="switch_section(this)" title="Click title to show/hide section content.">Questions About This FAQ</h1> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <div class="subsection"> <div class="head"> <h2 id="section_Why_is_this_FAQ_so_short_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Why is this FAQ so short?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> Because we don't have anyone maintaining it. </p> </div> </div> <div class="subsection"> <div class="head"> <h2 id="section_Can_I_help_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Can I help?</h2> <a href="#body" class="top" title="Back up to the top of the page" >Top</a> </div> <div class="body"> <p> Yes please :-) </p> </div> </div> </div> </div> </div></div> <br class="clear" /> <div class="pageinfo"> <a href="http://template-toolkit.org/docs/faq/index.html">http://template-toolkit.org/docs/faq/index.html</a> </div> </div> <div id="footer"> <a href="http://opensource.org/" class="osi"></a> <div class="controls"> <div class="pager"> <a href="../tutorial/index.html" title="Template::Tutorial" class="go back">Back<span class="about"><h4>Template::Tutorial</h4></span></a> <a href="../index.html" title="Template::Toolkit" class="go up">Up<span class="about"><h4>Template::Toolkit</h4></span></a> <span class="go next">Next<span class="about"></span></span> </div> </div> <div class="copyright"> Copyright © 1996-2012 <a href="http://wardley.org/">Andy Wardley</a>. All Rights Reserved. </div> <div class="licence"> The <a href="http://template-toolkit.org/">Template Toolkit</a> is <a href="http://opensource.org/">Open Source</a> software. You can redistribute and/or modify it under the terms of the <a href="http://www.opensource.org/licenses/gpl-license.php">GNU Public Licence</a> or the <a href="http://www.opensource.org/licenses/artistic-license.php">Perl Artistic Licence</a>. </div> </div> <div id="palette"> <ul> <li class="first"><a href="#" class="blue" onclick="set_style('Clear Blue')"></a></li> <li><a href="#" class="orange" onclick="set_style('Clear Orange')"></a></li> <li><a href="#" class="green" onclick="set_style('Clear Green')"></a></li> <li><a href="#" class="purple" onclick="set_style('Clear Purple')"></a></li> <li><a href="#" class="grey" onclick="set_style('Clear Grey')"></a></li> </ul> </div> </div> </body> </html>