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Template::Flute - Modern designer-friendly HTML templating Engine
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NAME
Template::Flute - Modern designer-friendly HTML templating Engine
VERSION
Version 0.027
SYNOPSIS
use Template::Flute;
my ($cart, $flute, %values);
$cart = [{...},{...}];
$values{cost} = ...
$flute = new Template::Flute(specification_file => 'cart.xml',
template_file => 'cart.html',
iterators => {cart => $cart},
values => \%values,
autodetect => {
disable => [qw/Foo::Bar/],
}
);
print $flute->process();
DESCRIPTION
Template::Flute enables you to completely separate web design and
programming tasks for dynamic web applications.
Templates are designed to be designer-friendly; there's no inline code
or mini templating language for your designers to learn - instead,
standard HTML and CSS classes are used, leading to HTML that can easily
be understood and edited by WYSIWYG editors and hand-coding designers
alike.
An example is easier than a wordy description:
Given the following template snippet:
<div class="customer_name">Mr A Test</div>
<div class="customer_email">[email protected]</div>
and the following specification:
<specification name="example" description="Example">
<value name="customer_name" />
<value name="email" class="customer_email" />
</specification>
Processing the above as follows:
$flute = Template::Flute->new(
template_file => 'template.html',
specification_file => 'spec.xml',
);
$flute->set_values({
customer_name => 'Bob McTest',
email => '[email protected]',
});;
print $flute->process;
The resulting output would be:
<div class="customer_name">Bob McTest</div>
<div class="email">[email protected]</div>
In other words, rather than including a templating language within your
templates which your designers must master and which could interfere
with previews in WYSIWYG tools, CSS selectors in the template are tied
to your data structures or objects by a specification provided by the
programmer.
Workflow
The easiest way to use Template::Flute is to pass all necessary
parameters to the constructor and call the process method to generate
the HTML.
You can also break it down in separate steps:
1. Parse specification
Parse specification based on your specification format (e.g with
Template::Flute::Specification::XML or
Template::Flute::Specification::Scoped.).
$xml_spec = new Template::Flute::Specification::XML;
$spec = $xml_spec->parse(q{<specification name="cart" description="Cart">
<list name="cart" class="cartitem" iterator="cart">
<param name="name" field="title"/>
<param name="quantity"/>
<param name="price"/>
</list>
<value name="cost"/>
</specification>});
2. Parse template
Parse template with Template::Flute::HTML object.
$template = new Template::Flute::HTML;
$template->parse(q{<html>
<head>
<title>Cart Example</title>
</head>
<body>
<table class="cart">
<tr class="cartheader">
<th>Name</th>
<th>Quantity</th>
<th>Price</th>
</tr>
<tr class="cartitem">
<td class="name">Sample Book</td>
<td><input class="quantity" name="quantity" size="3" value="10"></td>
<td class="price">$1</td>
</tr>
<tr class="cartheader"><th colspan="2"></th><th>Total</th>
</tr>
<tr>
<td colspan="2"></td><td class="cost">$10</td>
</tr>
</table>
</body></html>},
$spec);
3. Produce HTML output
$flute = new Template::Flute(template => $template,
iterators => {cart => $cart},
values => {cost => '84.94'});
$flute->process();
CONSTRUCTOR
new
Create a Template::Flute object with the following parameters:
specification_file
Specification file name.
specification_parser
Select specification parser. This can be either the full class name
like MyApp::Specification::Parser or the last part for classes
residing in the Template::Flute::Specification namespace.
specification
Specification object or specification as string.
template_file
HTML template file.
template
Template::Flute::HTML object or template as string.
filters
Hash reference of filter functions.
i18n
Template::Flute::I18N object.
translate_attributes
An arrayref of attribute names to translate. If the name has a dot,
it is interpreted as tagname + attribute, so placeholder" will
unconditionally translate all the placeholders, while
input.placeholder only the placeholder found on the input tag.
Additional dotted values compose conditions for attributes. E.g.
input.value.type.submit means all the value attributes with attribute
type set to submit.
Defaults to ['input.value.type.submit', 'placeholder']
iterators
Hash references of iterators.
values
Hash reference of values to be used by the process method.
auto_iterators
Builds iterators automatically from values.
autodetect
A configuration option. It should be an hashref with a key disable
and a value with an arrayref with a list of classes for objects which
should be considered plain hashrefs instead. Example:
my $flute = Template::Flute->new(....
autodetect => { disable => [qw/My::Object/] },
....
);
Doing so, if you pass a value holding a My::Object object, and you
have a specification with something like this:
<specification>
<value name="name" field="object.method"/>
</specification>
The value will be $object-{method}>, not $object-$method>.
The object is checked with isa.
Classical example: Dancer::Session::Abstract.
uri
Base URI for your template. This adjusts the links in the HTML tags
a, base, img, link and script.
email_cids
This is meant to be used on HTML emails. When this is set to an hash
reference (which should be empty), the hash will be populated with
the following values:
cid1 => { filename => 'foo.png' },
cid2 => { filename => 'foo2.gif' },
and in the body the images src attribute will be replaced with
cid:cid1.
The cid names are arbitrary and assigned by the template. The code
should look at the reference values which were modified.
cids
Optional hashref with options for the CID replacement behaviour.
By default, if the source looks like an HTTP/HTTPS URI, the image
source is not altered and no CID is assigned.
If you pass a base_url value in this hashref, the URI matching it
will be converted to cids and the rest of the path will be added to
the email_cids hashref.
Example:
my $cids = {};
$flute = Template::Flute->new(template => $template,
specification => $spec,
email_cids => $cids,
cids => {
base_url => 'http://example.com/'
});
Say the template contains images with source
http://example.com/image.png, the email_cids hashref will contain a
cid with filename "image.png".
METHODS
BUILD
Force creation of template class as soon as object is instantiated.
process [HASHREF]
Processes HTML template, manipulates the HTML tree based on the
specification, values and iterators.
Returns HTML output.
process_template
Processes HTML template and returns Template::Flute::HTML object.
filter ELEMENT VALUE
Runs the filter used by ELEMENT on VALUE and returns the result.
value NAME
Returns the value for NAME.
set_values HASHREF
Sets hash reference of values to be used by the process method. Same as
passing the hash reference as values argument to the constructor.
template
Returns HTML template object, see Template::Flute::HTML for details.
specification
Returns specification object, see Template::Flute::Specification for
details.
patterns
Returns all patterns found in the specification.
scopes
SPECIFICATION
The specification ties the elements in the HTML template to the data
(variables, lists, forms) which is added to the template.
The default format for the specification is XML implemented by the
Template::Flute::Specification::XML module. You can use the
Config::Scoped format implemented by
Template::Flute::Specification::Scoped module or write your own
specification parser class.
COMMON ATTRIBUTES
Common attributes for specification elements are:
name
Name of element.
<value name="dancefloor"/>
class
Class of corresponding elements in the HTML template.
<value name="dancefloor" class="dancefloor-link"/>
If this attribute is omitted, the value of the name attribute is used
to relate to the class in the HTML template.
id
Id of corresponding element in the HTML template. Overrides the class
attribute for the specification element.
<value name="dancefloor" id="dancefloor-link"/>
target
HTML attribute to fill the value instead of replacing the body of the
HTML element.
<value name="dancefloor" class="dancefloor-link" target="href"/>
joiner
String placed between the text and the appended value. The joiner
isn't added if the value is empty.
ELEMENTS
Possible elements in the specification are:
container
The first container is only shown in the output if the value
billing_address is set:
<container name="billing" value="billing_address" class="billingWrapper">
</container>
The second container is shown if the value warnings or the value
errors is set:
<container name="account_errors" value="warnings|errors" class="infobox">
<value name="warnings"/>
<value name="errors"/>
</container>
list
separator
Separator elements for list are added after any list item in the
output with the exception of the last one.
Example specification, HTML template and output:
<specification>
<list name="list" iterator="tokens">
<param name="key"/>
<separator name="sep"/>
</list>
</specification>
<div class="list"><span class="key">KEY</span></div><span class="sep"> | </span>
<div class="list"><span class="key">FOO</span></div><span class="sep"> | </span>
<div class="list"><span class="key">BAR</span></div>
param
Param elements are replaced with the corresponding value from the
list iterator.
The following operations are supported for param elements:
append
Appends the param value to the text found in the HTML template.
prepend
Prepends the param value to the text found in the HTML template.
target
The attribute to operate on. See below target for value for
details.
toggle
When the args attribute is set to tree, it doesn't interpolate
anything and just shows corresponding HTML element if param value
is set.
With target attribute, it simply toggles the target attribute.
Otherwise, if value is true, shows the HTML element and set its
content to the value. If value is false, removes the HTML element.
So, if your element has children elements, you probably want to use
the args="tree" attribute (see below for an example).
Other attributes for param elements are:
filter
Applies filter to param value.
increment
Uses value from increment instead of a value from the iterator.
<param name="pos" increment="1">
value
Value elements are replaced with a single value present in the values
hash passed to the constructor of this class or later set with the
set_values method.
The following operations are supported for value elements:
append
Appends the value to the text found in the HTML template.
prepend
Prepends the value to the text found in the HTML template.
hook
Insert HTML residing in value as subtree of the corresponding HTML
element. HTML will be parsed with XML::Twig. See "INSERT HTML" for
an example.
keep
Preserves the text inside of the HTML element if value is false in
the Perl sense.
toggle
Only shows corresponding HTML element if value is set.
Other attributes for value elements are:
target
Specify the attribute to operate on instead of the tag content. It
can be a named attribute (e.g., href), the wildcard character(*,
meaning all the attributes found in the HTML template), or a comma
separated list (e.g., alt,title).
filter
Applies filter to value.
include
Processes the template file named in this attribute. This implies
the hook operation. See "INCLUDE FILES" for more information.
form
Form elements are tied through specification to HTML forms.
Attributes for form elements in addition to class and id are:
link
The link attribute can only have the value name and allows to base
the relationship between form specification elements and HTML form
tags on the name HTML attribute instead of class, which is usually
more convenient.
input
filter
sort
i18n
skip
This attribute (which can be provided to param or value specification
elements) supports the following values:
empty
Do not replace the template string if the value or parameter is
undefined, empty or just whitespace.
E.g.
<value name="cartline" skip="empty"/>
<list name="items" iterator="items">
<param name="category" skip="empty"/>
</list>
pattern
You can define patterns in your specification to interpolate the
strings instead of replacing them.
A pattern is defined by the attributes name and type and its content.
type can be only string or regexp.
The interpolation happens if the value and param elements of the
specification have an attribute pattern set with the pattern's name.
Given this HTML:
<p class="cartline">There are 123 items in your shopping cart.</p>
<ul>
<li class="items">
<span class="number">1</span>
<span class="category">in category 123</span>
</li>
</ul>
And this specification:
<specification>
<pattern name="pxt" type="string">123</pattern>
<list name="items" iterator="items">
<param name="number"/>
<param name="category" pattern="pxt"/>
</list>
<value name="cartline" pattern="pxt"/>
</specification>
In this example, in the cartline and category classes' text, only the
template text "123" will be replaced by the value, not the whole
element content, yielding such output:
<p class="cartline">There are 42 items in your shopping cart.</p>
<ul>
<li class="items">
<span class="number">1</span>
<span class="category">in category tofu</span>
</li>
<li class="items">
<span class="number">2</span>
<span class="category">in category pizza</span>
</li>
</ul>
Note: All matches of the pattern are subject to replacement, starting
with version 0.025.
SIMPLE OPERATORS
append
Appends the value to the text inside a HTML element or to an attribute
if target has been specified. This can be used in value and param
specification elements.
The example shows how to add a HTML class to elements in a list:
HTML:
<ul class="nav-sub">
<li class="category"><a href="" class="catname">Medicine</a></li>
</ul>
XML:
<specification>
<list name="category" iterator="categories">
<param name="name" class="catname"/>
<param name="catname" field="uri" target="href"/>
<param name="css" class="catname" target="class" op="append" joiner=" "/>
</list>
</specification>
CONTAINERS
Conditional processing like IF or ELSE is done with the help of
containers.
Display image only if present
In this example we want to show an image only on a certain condition:
HTML:
<span class="banner-box">
<img class="banner" src=""/>
</span>
XML:
<container name="banner-box" value="banner">
<value name="banner" target="src"/>
</container>
Source code:
if ($organization eq 'Big One') {
$values{banner} = 'banners/big_one.png';
}
Display link in a list only if present
In this example we want so show a link only if an URL is available:
HTML:
<div class="linklist">
<span class="name">Name</span>
<div class="link">
<a href="#" class="url">Goto ...</a>
</div>
</div>
XML:
<specification name="link">
<list name="links" class="linklist" iterator="links">
<param name="name"/>
<param name="url" target="href"/>
<container name="link" class="link" value="url"/>
</list>
</specification>
Source code:
@records = ({name => 'Link', url => 'http://localhost/'},
{name => 'No Link'},
{name => 'Another Link', url => 'http://localhost/'},
);
$flute = Template::Flute->new(specification => $spec_xml,
template => $template,
iterators => {links => \@records});
$output = $flute->process();
ITERATORS
Template::Flute uses iterators to retrieve list elements and insert
them into the document tree. This abstraction relieves us from worrying
about where the data actually comes from. We basically just need an
array of hash references and an iterator class with a next and a count
method. For your convenience you can create an iterator from
Template::Flute::Iterator class very easily.
DROPDOWNS
Iterators can be used for dropdowns (HTML <select> elements) as well.
Template:
<select class="color"></select>
Specification:
<value name="color" iterator="colors"/>
Code:
@colors = ({value => 'red', label => 'Red'},
{value => 'black', label => 'Black'});
$flute = Template::Flute->new(template => $html,
specification => $spec,
iterators => {colors => \@colors},
values => {color => 'black'},
);
HTML output:
<select class="color">
<option value="red">Red</option>
<option value="black" selected="selected">Black</option>
</select>
Default value for dropdowns
You can specify the dropdown item which is selected by default with the
iterator_default) attribute.
Template:
<select class="color"></select>
Specification:
<value name="color" iterator="colors" iterator_default="black"/>
Code:
@colors = ({value => 'red', label => 'Red'},
{value => 'black', label => 'Black'});
$flute = Template::Flute->new(template => $html,
specification => $spec,
iterators => {colors => \@colors},
);
HTML output:
<select class="color">
<option value="red">Red</option>
<option value="black" selected="selected">Black</option>
</select>
Custom iterators for dropdowns
By default, the iterator for a dropdown is an arrayref of hashrefs with
two hardcoded keys: value and (optionally) label. You can override this
behaviour in the specification with iterator_value_key and
iterator_name_key to use your own hashref's keys from the iterator,
instead of value and label.
Specification:
<specification>
<value name="color" iterator="colors"
iterator_value_key="code" iterator_name_key="name"/>
</specification>
Template:
<html>
<select class="color">
<option value="example">Example</option>
</select>
</html>
Code:
@colors = ({code => 'red', name => 'Red'},
{code => 'black', name => 'Black'},
);
$flute = Template::Flute->new(template => $html,
specification => $spec,
iterators => {colors => \@colors},
values => { color => 'black' },
);
$out = $flute->process();
Output:
<html>
<head></head>
<body>
<select class="color">
<option value="red">Red</option>
<option selected="selected" value="black">Black</option>
</select>
</body>
</html>
Limit lists
Sometimes you may wish to limit the number or iterations through you
list.
Specification:
<specification>
<list name="images" iterator="images" limit="1">
<param name="image" target="src" field="image_url" />
</list>
</specification>
Template:
<div class="images">
<img class="image" src="/images/bottle.jpg" />
</div>
Code:
$images = [
{ image_url => '/images/bottle1.jpg' },
{ image_url => '/images/bottle2.jpg' },
{ image_url => '/images/bottle3.jpg' },
];
$flute = Template::Flute->new(
template => $html,
specification => $spec,
values => { images => $images },
);
$out = $flute->process;
Output:
<html><head></head><body>
<div class="images">
<img class="image" src="/images/bottle1.jpg" />
</div>
</body></html>
LISTS
Lists can be accessed after parsing the specification and the HTML
template through the HTML template object:
$flute->template->lists();
$flute->template->list('cart');
Only lists present in the specification and the HTML template can be
addressed in this way.
See Template::Flute::List for details about lists.
OBJECTS AND STRUCTURES
You can pass objects and hashrefs as values. To access a key or an
accessor, you have to use a dotted notation with field. An example for
both hashrefs and objects follows.
Specification:
<specification>
<value name="object" field="myobject.method" />
<value name="struct" field="mystruct.key" />
</specification>
HTML:
<html>
<body>
<span class="object">Welcome back!</span>
<span class="struct">Another one</span>
</body>
</html>
Code:
package My::Object;
sub new {
my $class = shift;
bless {}, $class;
}
sub method {
return "Hello from the method";
}
package main;
my $flute = Template::Flute->new(
specification => $spec,
template => $html,
values => {
myobject => My::Object->new,
mystruct => { key => "Hello from hash" },
}
);
process will return:
<html>
<head></head>
<body>
<span class="object">Hello from the method</span>
<span class="struct">Hello from hash</span>
</body>
</html>
Sometimes you need to treat an object like an hashref. How to do that
is explained under the autodetect option for the constructor.
FORMS
Forms can be accessed after parsing the specification and the HTML
template through the HTML template object:
$flute->template->forms();
$flute->template->form('edit_content');
Only forms present in the specification and the HTML template can be
addressed in this way.
See Template::Flute::Form for details about forms.
FILTERS
Filters are used to change the display of value and param elements in
the resulting HTML output:
<value name="billing_address" filter="eol"/>
<param name="price" filter="currency"/>
The following filters are included:
upper
Uppercase filter, see Template::Flute::Filter::Upper.
strip
Strips whitespace at the beginning at the end, see
Template::Flute::Filter::Strip.
eol
Filter preserving line breaks, see Template::Flute::Filter::Eol.
nobreak_single
Filter replacing missing text with no-break space, see
Template::Flute::Filter::NobreakSingle.
currency
Currency filter, see Template::Flute::Filter::Currency. Requires
Number::Format module.
date
Date filter, see Template::Flute::Filter::Date. Requires DateTime and
DateTime::Format::ISO8601 modules.
country_name
Country name filter, see Template::Flute::Filter::CountryName.
Requires Locales module.
language_name
Language name filter, see Template::Flute::Filter::LanguageName.
Requires Locales module.
json_var
JSON to Javascript variable filter, see
Template::Flute::Filter::JsonVar. Requires JSON module.
lower_dash
Replaces spaces with dashes (-) and makes lowercase. see
Template::Flute::Filter::LowerDash.
markdown
Turns text in Markdown format into HTML. see
Template::Flute::Filter::Markdown.
Requires Text::Markdown and HTML::Scrubber modules.
Filter classes are loaded at runtime for efficiency and to keep the
number of dependencies for Template::Flute as small as possible.
See above for prerequisites needed by the included filter classes.
Chained Filters
Filters can also be chained:
<value name="note" filter="upper eol"/>
Example template:
<div class="note">
This is a note.
</div>
With the following value:
Update now!
Avoid security hazards!
The HTML output would look like:
<div class="note">
UPDATE NOW!<br />
AVOID SECURITY HAZARDS!
</div>
INSERT HTML AND INCLUDE FILES
INSERT HTML
HTML can be generated in the code or retrieved from a database and
inserted into the template through the hook operation:
<value name="description" op="hook"/>
The result replaces the inner HTML of the following div tag:
<div class="description">
Sample content
</div>
INCLUDE FILES
Files, especially components for web pages can be processed and
included through value elements with the include attribute:
<value name="sidebar" include="component.html"/>
The result replaces the inner HTML of the following div tag:
<div class="sidebar">
Sample content
</div>
INSTALLATION
Template::Flute can be installed from the latest release on CPAN, or if
you wish for the very latest version, you can also install from the
sources on GitHub.
FROM CPAN
To install from CPAN, simply use the cpanm utility:
$ cpanm Template::Flute
FROM SOURCE
To install from source, first clone the repository, install the
required dependencies, and build:
$ git clone https://github.com/racke/Template-Flute
$ cd Template-Flute
$ cpanm --installdeps .
$ perl Makefile.PL
$ make
$ make test # optional, but still a good idea
$ make install
AUTHOR
Stefan Hornburg (Racke), <[email protected]>
BUGS
Please report any bugs or feature requests at
https://github.com/racke/Template-Flute/issues.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Template::Flute
You can also look for information at:
* AnnoCPAN: Annotated CPAN documentation
http://annocpan.org/dist/Template-Flute
* CPAN Ratings
http://cpanratings.perl.org/d/Template-Flute
* Search CPAN
http://search.cpan.org/dist/Template-Flute/
ACKNOWLEDGEMENTS
Thanks to Nitish Bezzala (GH #157).
Thanks to Mohammad S Anwar (GH #156).
Thanks to Paul Cochrane for his tremendous amount of pull requests
issued during the GitHub challenge.
Thanks to Peter Mottram (GH #81, #87).
Thanks to William Carr (GH #86, #91).
Thanks to David Precious (bigpresh) for writing a much clearer
introduction for Template::Flute.
Thanks to Grega Pompe for proper implementation of nested lists and a
documentation fix.
Thanks to Jeff Boes for spotting a typo in the documentation of the
Template::Flute::Filter::JsonVar class.
Thanks to Ton Verhagen for being a big supporter of my projects in all
aspects.
Thanks to Sam Batschelet (GH #14, #93).
Thanks to Terrence Brannon for spotting a documentation mix-up.
HISTORY
Template::Flute was initially named Template::Zoom. I renamed the
module because of a request from Matt S. Trout, author of the
HTML::Zoom module.
LICENSE AND COPYRIGHT
Copyright 2010-2021 Stefan Hornburg (Racke) <[email protected]>.
This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.
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