Introduction to Template::Toolkit

Introduction To
Template::Toolkit
Introduction
Basics: Part One
Exercises (Hands On)
Basics: Part Two
Exercises (Hands On)
References and Further Reading

Introduction
•Who am I?
•What level of Perl expertise is required?
•What is Template::Toolkit?

Part One

•Simple mail-merge type example

Template for a letter
Dear [% name %],

It has come to our attention that your account is in
arrears to the sum of [% debt %].

Please settle your account before [% deadline %] or we
will be forced to revoke your Licence to Thrill.

The Management.

Perl script to call it
use strict;
use Template;
my $tt = Template->new({
INCLUDE_PATH => '/usr/local/templates',
INTERPOLATE => 1,
}) || die "$Template::ERRORn";

my $vars = {
name => 'Count Edward van Halen',
debt => '3 riffs and a solo',
deadline => 'the next chorus',
};

$tt->process('letters/overdrawn', $vars)
|| die $tt->error(), "n";

Multiple letters
[% FOREACH d IN debtors %]
Dear [% d.name %],

arrears to the sum of [% d.debt %].

Please settle your account before [% d.deadline %] or we

The Management.
[% END %]

Perl fragment
my $vars = { debtors => [
{
},
{
name => ‘Baron Eric Clapton',
debt => ‘1 badge',
deadline => ‘tomorrow',
}
]
};

$tt->process('letters/overdrawn', $vars)

Multiple letters with logic
[% FOREACH d = debtors %]
Dear [% d.name %],

arrears to the sum of [% d.debt %].

Please settle your account before [% d.deadline %] or we

[% IF d.final %]This is your last chance.[% END %]

The Management.
[% END %]

Perl fragment
my $debtors = [
{
},
{
final => 1
}
];

$tt->process('letters/overdrawn', $debtors)

Boolean logic: IF ELSE
[% IF age < 10 %]
[% ELSIF age < 18 %]
[% ELSE %]
[% END %]

The following conditional and boolean operators may be used:
== != < <= > >= && || ! and or not

Boolean logic: SWITCH
[% SWITCH myvar %]
[% CASE 'value1' %]
[% CASE ['value2', 'value3'] %] # multiple values
[% CASE myhash.keys %] # ditto
[% CASE %] # default
[% END %]

Alternative contents
Dear [% d.name %],

Thank you for your recent payment of [% d.debt %].

Your account is now clear and you may continue to thrill.

The Management.
[% END %]

Include other templates
Dear [% d.name %],

[% IF d.angry -%]
[% INCLUDE angry_letter.tt2 %]
[% ELSE -%]
[% INCLUDE grateful_letter.tt2 %]
[% END -%]

The Management.
[% END %]

Perl fragment
my $debtors = [
{
},
{
final => 1,
angry => 1,
}
];

$tt->process('letters/overdrawn', $debtors)

Part Two
•Adding a wrapper for the header and footer
•Adding simple filters to encoding entities or control case
•Using a vmethod to add row numbers
•Sorting a select list
•Formatting currency

Adding a wrapper
Content-Type: text/html; charset=ISO-8859-1

<html>
<head>
</head>
<body>
<h1>Introduction to TT</h2>

[%# Header and footer will be the same on all pages %]

<table>
<tr><th>Something</th><th>Something Else</th></tr>
[% FOREACH r IN rows %]
<tr><td>[% r.something %]</td><td>[% r.something_else %]</td></tr>
[% END %]
</table>

</body>
</html>

Move the common content to wrapper.tt

Content-Type: text/html; charset=ISO-8859-1

<html>
<head>
</head>
<body>
<h1>Introduction to TT</h2>

[% content %]

</body>
</html>

Tell TT about the wrapper
#! /usr/bin/perl

use strict; use warnings; use CGI; use Template;

# Using a wrapper.

my $tt = Template->new(
{
INCLUDE_PATH => '/home/duncan/tt/htdocs/tt2',
INTERPOLATE => 1,
WRAPPER => 'wrapper.tt2'
}
) || die "$Template::ERRORn";

$tt->process(
's2.tt2',
{
rows => [
{ something => 'apples', something_else => '1 kg' },
{ something => 'pears', something_else => '2 kg' }
]
}
) || die $tt->error() . "n";

Dodgy data
{
INTERPOLATE => 1,
}

$tt->process(
's2.tt2',
{
rows => [
{ something => 'pears', something_else => '2 kg' },
{ something => 'turnips > pears > grapes', something_else => '2 & 3 kg' },
{ something => '<script type="text/javascript">alert("Hi");</script>', something_else => '2
& 3 kg' },
]
}
) || die $tt->error() . "n";

Encode it!
<! [% component.name %] -->

[%# Using a filter to encode entities and control case. %]

<table>
<tr><th>Something</th><th>Something Else</th></tr>
<tr><td>[% r.something FILTER html_entity %]</td><td>[% r.something_else FILTER html_entity
FILTER upper %]</td></tr>
[% END %]
</table>

That’s better
<tr><td>apples</td><td>1 KG</td></tr> <tr><td>pears</td><td>2 KG</td></tr>

<tr><td>turnips > pears > grapes</td><td>2 & 3 KG</td></tr>

<tr><td><script
type="text/javascript">alert("Hi");</script></td><td>2 & 3
KG</td></tr>

Use a vmethod to add row
numbers

[%# Using a vmethod to add row number %]

<table>
<tr><th>No</th><th>Something</th><th>Something Else</th></tr>
<tr><td>([% loop.index %])</td>
<td>[% r.something FILTER html_entity %]</td><td>[% r.something_else FILTER html_entity
FILTER upper %]</td></tr>
[% END %]
</table>

With row numbers
No Something Something Else

(0) apples 1 KG

(1) pears 2 KG

(2) turnips > pears > grapes 2 & 3 KG

(3) <>peas 2 & 3 KG

(4) apricots 2 & 3 KG

Use a vmethod to do a simple sort
on a select list.
{
INTERPOLATE => 1,
}

$tt->process(
's5.tt2',
{
rows => [
{ something => 'pears', something_else => '2 kg' },
{ something => 'turnips > pears > grapes', something_else => '2 & 3 kg' },
{ something => '<>peas', something_else => '2 & 3 kg' },
{ something => 'apricots', something_else => '2 & 3 kg' },
],
suppliers => [ 'Fred', 'Alan', 'Joe', 'Bert' ]
}
) || die $tt->error() . "n";

Adding the sort vmethod
[%# Using a vmethod to do a simple sort on a select list %]


<select>
[% FOREACH s IN suppliers.sort %]
<option value="s"/>[% s %]
[% END %]
</select>

<table>
<tr><th>No</th><th>Something</th><th>Something Else</th></tr>
<tr><td> ([% loop.index %])</td><td>[% r.something FILTER html_entity %]</td><td>[%
r.something_else FILTER html_entity FILTER upper %]</td></tr>
[% END %]
</table>

Using the Format plugin on
currency

No Something Something Else Cost
(0) apples 1 KG £5.67
(1) pears 2 KG £3.33333333333333

(2) turnips > pears > grapes 2 & 3 KG £4.123

(3) <>peas 2 & 3 KG £2
(4) apricots 2 & 3 KG £3

The script with the plugin
[% USE money=format('%.2f') -%]

<select>
[% FOREACH s IN suppliers.sort %]
<option value="s"/>[% s %]
[% END %]
</select>

<table>
<tr><th>No</th><th>Something</th><th>Something Else</th><th>Cost</ht></tr>
<tr><td> ([% loop.index %])</td><td>[% r.something FILTER html_entity %]</td><td>[%
r.something_else FILTER html_entity FILTER upper %]</td><td>£[% money(r.cost)
%]</td></tr>
[% END %]
</table>

Further Reading
Template Toolkit [Paperback]
•Darren Chamberlain,
•Dave Cross,
•Andy Wardley

Also documented on MetaCPAN: https://metacpan.org/

It has its own website: http://www.template-toolkit.org/

226 plugins listed on MetaCPAN

Introduction to Template::Toolkit

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