NAME

Positron::DataTemplate - templating plain data to plain data

VERSION

version v0.0.2

SYNOPSIS

    my $engine   = Positron::DataTemplate->new();
    my $template = { contents => ['@list', '$title'] };
    my $data     = { list => [
        { title => 'first title', url => '/first-title.html' },
        { title => 'second title', url => '/second-title.html' },
    ] };
    my $result   = $engine->process($template, $data);
    # { contents => [ 'first title', 'second title' ] }

DESCRIPTION

Positron::DataTemplate is a templating engine. Unlike most templating engines, though, it does not work on text, but on raw data: the template is (typically) a hash or array reference, and the result is one, too.

This module rose from a script that regularly produced HTML snippets on disk, using regular, text-based templates. Each use case used the same data, but a different template. For one use case, however, the output was needed in JSON format, not HTML. One solution would have been to use the text-based templating system to produce a valid JSON document (quite risky). The other solution, which was taken at that time, was to transform the input data into the desired output structure in code, and use a JSON serializer on that, bypassing the template output.

The third solution would have been to provide a template that did not directly produce the serialised JSON text, but described the data structure transformation in an on-disc format. By working only with structured data, and never with text, the serialized output must always be valid JSON.

This (minus the serialization) is the domain of Positron::DataTemplate.

EXAMPLES

This code is still being worked on. This includes the documentation. In the meanwhile, please use the following examples (and some trial & error) to gain a first look. Alternatively, if you have access to the tests of this distribution, these also give some examples.

Text replacement

  [ '$one', '{$two}', 'and {$three}' ] + { one => 1, two => 2, three => 3 }
  -> [ '1', '2', 'and 3' ]

Direct inclusion

  [ '&this', '&that' ] + { this => [1, 2], that => { 3 => 4 } }
  -> [ [1, 2], { 3 => 4} ]

Loops

  { titles => ['@list', '{$id}: {$title}'] }
  + { list => [ { id => 1, title => 'one' }, { id => 2, title => 'two' } ] }
  -> { titles => [ '1: one', '2: two' ] }

Conditions

  { checked => ['?active', 'yes', 'no] } + { active => 1 }
  -> { checked => 'yes' }