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<h1 class="headline">Template::FAQ</h1>
<h2 class="subhead">Frequently Asked Questions about the Template Toolkit</h1>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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<h1 id="Questions_About_This_FAQ" onclick="switch_section(this)" title="Click title to show/hide section content.">Questions About This FAQ</h1>
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<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>
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<h2 id="section_Can_I_help_" onclick="switch_subsection(this)" title="Click title to show/hide sub-section content.">Can I help?</h2>
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<p>
Yes please :-)
</p>
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<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>