The new() constructor method is called to instantiate a Template::Service
object. Configuration parameters may be specified as a HASH reference or
as a list of (name => value) pairs.
The new() method returns a Template::Service object (or sub-class) or
undef on error. In the latter case, a relevant error message can be
retrieved by the error() class method or directly from the
$Template::Service::ERROR package variable.
- PRE_PROCESS, POST_PROCESS
These values may be set to contain the name(s) of template files
(relative to INCLUDE_PATH) which should be processed immediately
before and/or after each template. These do not get added to
templates processed into a document via directives such as INCLUDE,
PROCESS, WRAPPER etc.
my $service = Template::Service->new({
PRE_PROCESS => 'header',
POST_PROCESS => 'footer',
};
Multiple templates may be specified as a reference to a list. Each is
processed in the order defined.
my $service = Template::Service->new({
PRE_PROCESS => [ 'config', 'header' ],
POST_PROCESS => 'footer',
};
Alternately, multiple template may be specified as a single string,
delimited by ':'. This delimiter string can be changed via the
DELIMITER option.
my $service = Template::Service->new({
PRE_PROCESS => 'config:header',
POST_PROCESS => 'footer',
};
The PRE_PROCESS and POST_PROCESS templates are evaluated in the same
variable context as the main document and may define or update
variables for subsequent use.
config:
[% # set some site-wide variables
bgcolor = '#ffffff'
version = 2.718
%]
header:
[% DEFAULT title = 'My Funky Web Site' %]
<html>
<head>
<title>[% title %]</title>
</head>
<body bgcolor="[% bgcolor %]">
footer:
<hr>
Version [% version %]
</body>
</html>
The Template::Document object representing the main template being processed
is available within PRE_PROCESS and POST_PROCESS templates as the 'template'
variable. Metadata items defined via the META directive may be accessed
accordingly.
$service->process('mydoc.html', $vars);
mydoc.html:
[% META title = 'My Document Title' %]
blah blah blah
...
header:
<html>
<head>
<title>[% template.title %]</title></head>
<body bgcolor="[% bgcolor %]">
- PROCESS
The PROCESS option may be set to contain the name(s) of template files
(relative to INCLUDE_PATH) which should be processed instead of the
main template passed to the Template::Service process() method. This can
be used to apply consistent wrappers around all templates, similar to
the use of PRE_PROCESS and POST_PROCESS templates.
my $service = Template::Service->new({
PROCESS => 'content',
};
# processes 'content' instead of 'foo.html'
$service->process('foo.html');
A reference to the original template is available in the 'template'
variable. Metadata items can be inspected and the template can be
processed by specifying it as a variable reference (i.e. prefixed by
'$') to an INCLUDE, PROCESS or WRAPPER directive.
content:
<html>
<head>
<title>[% template.title %]</title>
</head>
<body>
[% PROCESS $template %]
<hr>
© Copyright [% template.copyright %]
</body>
</html>
foo.html:
[% META
title = 'The Foo Page'
author = 'Fred Foo'
copyright = '2000 Fred Foo'
%]
<h1>[% template.title %]</h1>
Welcome to the Foo Page, blah blah blah
output:
<html>
<head>
<title>The Foo Page</title>
</head>
<body>
<h1>The Foo Page</h1>
Welcome to the Foo Page, blah blah blah
<hr>
© Copyright 2000 Fred Foo
</body>
</html>
- ERROR
The ERROR (or ERRORS if you prefer) configuration item can be used to
name a single template or specify a hash array mapping exception types
to templates which should be used for error handling. If an uncaught
exception is raised from within a template then the appropriate error
template will instead be processed.
If specified as a single value then that template will be processed
for all uncaught exceptions.
my $service = Template::Service->new({
ERROR => 'error.html'
});
If the ERROR item is a hash reference the keys are assumed to be
exception types and the relevant template for a given exception will
be selected. A 'default' template may be provided for the general
case. Note that 'ERROR' can be pluralised to 'ERRORS' if you find
it more appropriate in this case.
my $service = Template::Service->new({
ERRORS => {
user => 'user/index.html',
dbi => 'error/database',
default => 'error/default',
},
});
In this example, any 'user' exceptions thrown will cause the
'user/index.html' template to be processed, 'dbi' errors are handled
by 'error/database' and all others by the 'error/default' template.
Any PRE_PROCESS and/or POST_PROCESS templates will also be applied
to these error templates.
Note that exception types are hierarchical and a 'foo' handler will
catch all 'foo.*' errors (e.g. foo.bar, foo.bar.baz) if a more
specific handler isn't defined. Be sure to quote any exception types
that contain periods to prevent Perl concatenating them into a single
string (i.e. 'user.passwd' is parsed as 'user'.'passwd').
my $service = Template::Service->new({
ERROR => {
'user.login' => 'user/login.html',
'user.passwd' => 'user/badpasswd.html',
'user' => 'user/index.html',
'default' => 'error/default',
},
});
In this example, any template processed by the $service object, or
other templates or code called from within, can raise a 'user.login'
exception and have the service redirect to the 'user/login.html'
template. Similarly, a 'user.passwd' exception has a specific
handling template, 'user/badpasswd.html', while all other 'user' or
'user.*' exceptions cause a redirection to the 'user/index.html' page.
All other exception types are handled by 'error/default'.
Exceptions can be raised in a template using the THROW directive,
[% THROW user.login 'no user id: please login' %]
or by calling the throw() method on the current Template::Context object,
$context->throw('user.passwd', 'Incorrect Password');
$context->throw('Incorrect Password'); # type 'undef'
or from Perl code by calling die() with a Template::Exception object,
die (Template::Exception->new('user.denied', 'Invalid User ID'));
or by simply calling die() with an error string. This is
automagically caught and converted to an exception of 'undef'
type which can then be handled in the usual way.
die "I'm sorry Dave, I can't do that";
- AUTO_RESET
The AUTO_RESET option is set by default and causes the local BLOCKS
cache for the Template::Context object to be reset on each call to the
Template process() method. This ensures that any BLOCKs defined
within a template will only persist until that template is finished
processing. This prevents BLOCKs defined in one processing request
from interfering with other independent requests subsequently
processed by the same context object.
The BLOCKS item may be used to specify a default set of block definitions
for the Template::Context object. Subsequent BLOCK definitions in templates
will over-ride these but they will be reinstated on each reset if AUTO_RESET
is enabled (default), or if the Template::Context reset() method is called.
- DEBUG
The DEBUG option can be used to enable debugging messages from the
Template::Service module by setting it to include the DEBUG_SERVICE
value.
use Template::Constants qw( :debug );
my $template = Template->new({
DEBUG => DEBUG_SERVICE,
});
The process() method is called to process a template specified as the first
parameter, $input. This may be a file name, file handle (e.g. GLOB or IO::Handle)
or a reference to a text string containing the template text. An additional
hash reference may be passed containing template variable definitions.
The method processes the template, adding any PRE_PROCESS or POST_PROCESS
templates defined, and returns the output text. An uncaught exception thrown
by the template will be handled by a relevant ERROR handler if defined.
Errors that occur in the PRE_PROCESS or POST_PROCESS templates, or those that
occur in the main input template and aren't handled, cause the method to
return undef to indicate failure. The appropriate error message can be
retrieved via the error() method.
Returns a reference to the internal context object which is, by default, an
instance of the Template::Context class.
