README

WordPress with Twig on budget.

Make WordPress use ".php" and ".html.twig" theme templates
Split model from view by using filters or $wp_query
Inherit from multiple themes instead of just one parent

Installation / Usage

Require via composer:

composer require rmp-up/wp-twig

And add to your "functions.php" or elsewhere:

<?php

wp_twig_register();

This function exists when composer's autoload.php is used. From now on WordPress uses ".php" and ".html.twig" templates.

Templating / How Twig works

See given files in this repo like the "index.html.twig" file:

<html>
<body>
    <div class="menu"> <a href="/">HOME</a> :: <a href="/index.php?s=404">Why?</a> </div>
    <hr>
  
    {% block foo %}
        Hello world!
    {% block %}

</body>
</html>

So by default this page shows "Hello world". In other templates we can use the surrounding HTML but replace blocks:

{% extends 'wp-twig/index.html.twig' %}

{% block foo %}
    Search results are:

    ...
{% endblock %}

Note: The path to the theme itself is also needed. This way it is possible to access files of other themes.

Using (WordPress-)Functions

Twig is extended in a way that any function can be used as a filter. This means functions like date_i18n('l, d.m.Y') or wp_list_pluck are available as filter and function:

{{ "l, d.m.Y"|date_i18n }}
{# same as #}
{{ date_i18n("l, d.m.Y") }}

{{ some_posts|wp_list_pluck('ID') }}
{{ wp_list_pluck(some_posts, 'ID') }}

{{ __("translate this!", "wp-twig") }}

But for the sake of segregation and performance, don't do get_posts('post_type=foo') within a template. Data, lists and other expensive things should be injected as follows.

Data- / Model-Layer

Injecting data via WP_Query

Since WordPress 1.5 you can inject data in templates using $wp_query->query_vars. The load_template function (and locate_template in some cases) extracts the data as variables and so does wp-twig:

<?php

add_filter(
    'init',
    static function () {
        global $wp_query;
  
        $wp_query->query_vars['user'] = wp_get_current_user();  
    }
);

This is how you may have injected data in templates until now and it is still available in Twig:

{% if user %}
    Hello {{ user.user_nicename }}
{% else %}
    Hello guest!
{% endif %}

Injecting variables in the Twig-Context

It gives you four filter for injecting data:

wp_twig_template_{type}_block_{name} (e.g. "wp_twig_template_404_block_foo")
wp_twig_block_{name} (e.g. "wp_twig_block_foo")
wp_twig_template_{type} (e.g. "wp_twig_template_index" or "wp_twig_template_search")
wp_twig_context

Those are executed in the given order so you can basically add data to templates:

<?php

add_filter(
  'wp_twig_template_page_block_foo',
  static function ( array $context ) {
    $context['bar'] = 42;

    return $context;
  }
);

The order is important to bypass already added data on the more generic levels:

<?php

add_filter(
  'wp_twig_block_foo', // more generic than "wp_twig_template_page_block_foo" from above
  static function ( array $context ) {
    if ( ! array_key_exists( 'bar', $context ) ) {
        $context['bar'] = apply_filters( 'fetch_some_expensive_data', [] );
    }

    return $context;
  }
);

Bypassing the generation of data spares some time which results in a better performance of the theme. We suggest that you encapsulate data in a Generator of other lazy contructs to enhance this even more.

rmp / wp-twig

Maintainers

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