NAME¶
Template::FAQ - Frequently Asked Questions about the Template Toolkit
Why doesn't [% a = b IF c %] work as expected?¶
There'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 %]?¶
You 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?¶
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¶
How do I get the Table plugin to order data across rather than
down?¶
Order 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¶
Jeff 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 %]
Can I serve templates from a database?¶
Short 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?¶
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
<
http://tt2.org/pipermail/templates/2001-May/000954.html>
Miscellaneous¶
How can I find out the name of the main template being
processed?¶
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?¶
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?¶
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) %]
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?¶
First 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'
});
Questions About This FAQ¶
Why is this FAQ so short?¶
Because we don't have anyone maintaining it.
Can I help?¶
Yes please :-)