Contents
Top- Template Toolkit Language
- Why doesn't [% a = b IF c %] work as expected?
- If I'm using TT to write out a TT template, is there a good way to escape [% and %]?
- How do I iterate over a hash?
- Plugins
- How do I get the Table plugin to order data across rather than down?
- Accessing Cookies
- Extending the Template Toolkit
- Can I serve templates from a database?
- Can I fetch templates via http?
- Miscellaneous
- How can I find out the name of the main template being processed?
- How can I find out the name of the current template being processed?
- How do I print the modification time of the template or component?
- How can I configure variables on a per-request basis?
- Why do I get rubbish for my utf-8 templates?
- Questions About This FAQ
- Why is this FAQ so short?
- Can I help?
Template Toolkit Language
TopWhy doesn't [% a = b IF c %] work as expected?
TopThere's a limitation in the TT2 parser which means that the following code doesn't work as you might expect:
[% a = b IF c %]
                        
                          The parser interprets it as an attempt to set a to the
                          result of b IF c, like this:
                        
[% a = (b IF c) %]
                        
                          If you want to set a = b only if c is true,
                          then do this instead:
                        
[% SET a = b IF c %]
                        
                          The explicit SET keyword gives the parser the clue it needs
                          to do the right thing.
                        
NOTE: this will be fixed in TT3
If I'm using TT to write out a TT template, is there a good way to escape [% and %]?
TopYou can do something like this:
[% stag = "[\%"
   etag = "%\]"
%]
                        and then:
[% stag; 'hello'; etag %]
                        
                          Or you can use the TAGS directive, like so:
                        
[% TAGS [- -] %] [- INCLUDE foo -] # is a directive [% INCLUDE foo %] # not a directive
How do I iterate over a hash?
Top
                          This is covered in the Template::Manual::VMethods section of the manual. A list of all
                          the keys that are in the hash can be obtained with the keys
                          virtual method. You can then iterate over that list and by looking up
                          each key in turn get the value.
                        
[% FOREACH key = product.keys %] [% key %] => [% product.$key %] [% END %]
Plugins
TopHow do I get the Table plugin to order data across rather than down?
TopOrder the data into rows:
Steve     Karen     Jeff
Brooklyn  Nantucket Fairfax
NY        MA        VA
[% USE table(data, rows=3) %]
                        Then ask for each column
[% FOREACH column = table.cols %]
                        And then print each item in the column going across the output rows
[% FOREACH item = column %] <td>[% item %]</td> [% END %]
Accessing Cookies
TopJeff Boes <jboes@nexcerpt.com> asks:
Does anyone have a quick-n-dirty approach to accessing cookies from templates?
Jonas Liljegren answers:
[% USE CGI %] <p>The value is [% CGI.cookie('cookie_name') | html %]
Extending the Template Toolkit
TopCan I serve templates from a database?
TopShort answer: yes, Chris Nandor has done this for Slash. You need to subclass Template::Provider. See the mailing list archives for further info.
Can I fetch templates via http?
Top
                          To do the job properly, you should subclass Template::Provider to
                          Template::Provider::HTTP and use a PREFIX_MAP
                          option to bind the http template prefix to that particular
                          provider (you may want to go digging around in the Changes file
                          around version 2.01 for more info on PREFIX_MAP - it may not
                          be properly documented anywhere else...yet!). e.g.
                        
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
    }
});
                        Now a template specified as:
[% INCLUDE foo %]
                        will be served by the 'file' provider (the default). Otherwise you can explicitly add a prefix:
[% INCLUDE file:foo.html %] [% INCLUDE http:foo.html %] [% INCLUDE http://www.xyz.com/tt2/header.tt2 %]
This same principal can be used to create a DBI template provider. e.g.
[% INCLUDE dbi:foo.html %]
                        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...
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 http://tt2.org/pipermail/templates/2001-May/000954.html
Miscellaneous
TopHow can I find out the name of the main template being processed?
Top
                          The template 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 name method returns its name.
                        
[% template.name %]     # e.g. index.html
                  How can I find out the name of the current template being processed?
Top
                          The template variable always references the main
                          template being processed. So even if you call [% INCLUDE header %], and
                          that calls [% INCLUDE menu %], the template variable will be
                          unchanged.
                        
index.html:
[% template.name %] # index.html [% INCLUDE header %]
header:
[% template.name %] # index.html [% INCLUDE menu %]
menu:
[% template.name  %]     # index.html
                        
                          In constrast, the component variable always references the
                          current template being processed.
                        
index.html
[% component.name %] # index.html [% INCLUDE header %]
header:
[% component.name %] # header [% INCLUDE menu %]
menu:
[% component.name  %]     # menu
                  How do I print the modification time of the template or component?
Top
                          The template and component variables reference
                          the main template and the current template being processed (see previous
                          questions). The modtime 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).
                        
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.
[% USE Date %] [% template.name %] last modified [% Date.format(template.modtime) %]
How can I configure variables on a per-request basis?
Top
                          One easy way to achieve this is to define a single
                          PRE_PROCESS template which loads in other configuration
                          files based on variables defined or other conditions.
                        
For example, my setup usually looks something like this:
PRE_PROCESS => 'config/main'
config/main:
[%  DEFAULT  style   = 'text'
             section =  template.section or 'home';
    PROCESS  config/site
          +  config/urls
          +  config/macros
          + "config/style/$style"
          + "config/section/$section"
          + ...
%]
                        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:
config/style/basic:
[%  style = {
        name = style    # save existing 'style' var as 'style.name'
        # define various other style variables....
        col = {
            back => '#ffffff'
            text => '#000000'
                # ...etc...
        }
        logo = {
                # ...etc...
        }
        # ...etc...
    }
%]
                        Each source template can declare which section it's in via a META directive:
[% META
 title   = 'General Information'
 section = 'info'
%]
...
                        This controls which section configuration file gets loaded to set various other variables for defining the section title, menu, etc.
config/section/info:
[%  section = {
        name   = section  # save 'section' var as 'section.name'
        title  = 'Information'
        menu   = [ ... ]
        # ...etc...
    }
%]
                        This illustrates the basic principal but you can extend it to perform pretty much any kind of per-document initialisation that you require.
Why do I get rubbish for my utf-8 templates?
TopFirst of all, make sure that your template files define a Byte Order Mark http://en.wikipedia.org/wiki/Byte_Order_Mark
                          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. utf8) for
                          your templates with the ENCODING option.
                        
my $template = Template->new({ 
    ENCODING => 'utf8' 
});