Craft 3 Templates: Experimenting with Twig Objects as HTML building blocks

base.twig

{#

# Craft 3 Templates: Experimenting with Twig Objects as HTML building blocks

Ben Rogerson <info@benrogerson.com.au> 2018

This Gist explores a way to create HTML from a formatted TWIG object. 
I found it encourages a different way of thinking when writing HTML.

Here's an example that uses the emmet shorthand to create a `<button>` with a `<main>` parent.

In TWIG Templates:

{{ self.render(
    [{
        abbr: 'main.item.item--hasbutton#anchor',
        inner: [{
            abbr: 'button.item__button',
            inner: 'Send',
        }]
    }]
) }}

Output HTML:

<main class="item item--hasbutton" id="anchor">
    <button class="item__button">Send</button>
</main>

## Features
- Emmet style for element creation (includes class or id)
- Some Twig macro weirdness to get the job done

## How to use this
Paste this whole Gist into a .twig file within your Craft 3 installation.
You'll see a few examples that show up for easy tweaking.

## This work is experimental
You're likely to find bugs here and there.

#}

{#
================================================================================
Add Attributes Macro
================================================================================

Converts an object to a list of attributes. Great for keeping things clean when
working with a bunch of values. If value is falsy then it won't output the
attribute.

Usage:

{% set attributes = {
    class: 'link'
    href: '#',
    target: link.blank ? "_blank",
} %}
<a {{ utils.addAttributes(attributes) }}>Text</a>

#}

{% macro addAttributes(attributes) %}{{' '}}{% spaceless %}
    {% set output %}
        {% for key, value in attributes %}{{' '}}{% spaceless %}
            {% set keyValue = "=\"#{value|join(' ')}\"" %}
            {{ key }}{{ keyValue|raw }}
        {% endspaceless %}{% endfor %}
    {% endset %}
    {{ output|trim|raw }}{% endspaceless %}
{% endmacro %}


{#
================================================================================
Render Items Macro
================================================================================

Creates html elements from a structured twig object.

Usage:

{{ macro.render([
        {
            abbr: 'div.container',
            inner: 'Inside content'
        }
]) }}

{{ macro.render(
    [{
        abbr: 'main.item.item--hasbutton#anchor',
        inner: [{
            abbr: 'button.item__button',
            inner: 'Send',
        }]
    }]
) }}


#}

{% macro render(items) %}
    {% import _self as self %}

    {% for item in items %}

        {#
            match words starting with .# and include --
            match words starting with .# and include -
            match words starting with .#
            match [anything]
            TODO: improve regex
        #}
        {% set itemElement = (item.abbr|default
            ? item.abbr|replace('/([.#]\\w+--?\\w+)|([.#]\\w+-?\\w+)|(\\[[^\[\\]]+\\])/', '')
            : (item.element ?? 'div')
        ) %}

        {# TODO: improve regex #}
        {% set class = item.abbr|default ? item.abbr|replace('/([#]\\w+-?\\w+)|(\\[[^\[\\]]+\\])/', '')|split('.')|slice(1) %}
        {% set id = item.abbr|default ? item.abbr|replace('/([.]\\w+-?\\w+)|(\\[[^\[\\]]+\\])/', '')|split('#')|slice(1) %}

        {% set itemAttributes =
            self.addAttributes(
                item.abbr|default
                ? (
                    {}|merge(
                        (class ? {class: class} : {})
                    )|merge(
                        (id ? {id: id} : {})
                    )
                )
                : item.attributes|default
            )
        %}

        {# Some elements like img doesn't have an end tag so lets cater #}
        {% if 'img' in itemElement %}

            <{{ itemElement }}{{ itemAttributes }} />

        {% else %}

            <{{ itemElement }}{{ itemAttributes }}>{% spaceless %}
                {% if item.inner|default is iterable %}
                    {{ self.render(item.inner) }}
                {% else %}
                    {{ item.inner|default|raw }}
                {% endif %}
            {% endspaceless %}</{{ itemElement }}>

        {% endif %}

    {% endfor %}

{% endmacro %}



{#
================================================================================
Create a container with button inside
================================================================================
#}

{{ self.render(
    [{
        abbr: 'main.item.item--hasbutton#anchor',
        inner: [{
            abbr: 'button.item__button',
            inner: 'Send',
        }]
    }]
) }}

{#
Output:

<main class="item item--hasbutton" id="anchor">
    <button class="item__button">Send</button>
</main>

#}


{#
================================================================================
Add some more attributes
================================================================================
#}

{{ self.render(
    [{
        element: 'main',
        attributes: {
            class: ['item','item--has-button'],
            'data-name': 'button-parent',
        },
        inner: [{
            element: 'button',
            attributes: {
                class: 'item__button',
                type: 'submit',
            },
            inner: 'Send',
        }]
    }]
) }}

{#
Output:

<main class="item item--has-button" data-name="button-parent">
    <button class="item__button" type="submit">Send</button>
</main>

#}


{#
================================================================================
Add a conditional button
================================================================================
#}

{% set showButton = false %}

{{ self.render(
    [{
        element: 'main',
        attributes: {
            class: [
                'item',
                showButton ? 'item--has-button' : 'item--no-button'
            ],
        },
        inner: [
            showButton
            ? theButton
            : {
                abbr: 'div.item__note',
                inner: 'Sorry, no button here'
            }
        ]
    }]
) }}

{#
Output:

<main class="item item--no-button">
    <div class="item__note">Sorry, no button here</div>
</main>

#}