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">someone@example.com</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 => 'bob@example.com',
        });;
        print $flute->process;

    The resulting output would be:

        <div class="customer_name">Bob McTest</div>
        <div class="email">bob@example.com</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), <racke@linuxia.de>

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) <racke@linuxia.de>.

    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.

