Django IncludeContents tag

Provides a component-like {% includecontents %} tag to Django.

For example:

{% load includecontents %}
{% includecontents "hello.html" %}
    <p>World</p>
{% endincludecontents %}

It also provides an optional Django template engine that extends this tag to work like an HTML component.

In this example, it will include and render components/pretty-card.html:

<include:pretty-card title="Hello">
  <p>World</p>
</include:pretty-card>

This engine also allows for multi-line template tags. For example:

{% if 
  user.is_authenticated
  and user.is_staff
%}
...
{% endif %}

Installation

pip install django-includecontents

Either install the custom template engine or just add this app to your INSTALLED_APPS.

Install with template engine

Replace the default django.template.backends.django.DjangoTemplates backend in your settings:

TEMPLATES = [
    {
        'BACKEND': 'includecontents.django.DjangoTemplates',
        ...
    },
]

This engine also adds includecontents to the built-in tag libraries so there is no need to load it in your templates.

Install without template engine

Alternatively, add this app to your INSTALLED_APPS and use {% load includecontents %} in your templates:

INSTALLED_APPS = [
    ...
    'includecontents',
]

Template tag usage

The includecontents tag works like the include tag but the contents is rendered and passed to the included template as a contents variable.

{% includecontents "hello.html" %}
    <p>World</p>
{% endincludecontents %}

Named contents blocks

You can also have named contents blocks within the component content.

For example:

{% includecontents "hello.html" %}
    <p>World</p>
    {% contents footer %}Footer{% endcontents %}
{% endincludecontents %}

Where hello.html template could look something like:

<div class="card">
  <div class="content">
    {{ contents }}
  </div>
  {% if contents.footer %}
  <div class="footer">
    {{ contents.footer }}
  </div>
  {% endif %}
</div>

HTML Components Usage

This requires the custom template engine to be installed.

Create a components directory in your templates directory. This is where you will put your component templates that are used via the HTML component format. These components are normal Django templates that will be rendered with an isolated context. The context is passed to the component via component's attributes.

Components must not match any standard HTML tags. Actually, it's best practice to name them as HTML custom elements (1 or more ASCII letters; a hyphen; 1 or more more ASCII letters, digits or hyphens).

For example, a components/my-card.html template could look like:

<div class="card">
  <h2>{{ title }}</h2>
  <div class="content">
    {{ contents }}
  </div>
</div>

Components are always rendered isolated from the parent template, so they should not rely on any context variables from the parent template.

Which will allow you to use it like this (without the need to load any template library):

<include:my-card title="Hello">
  <p>World</p>
</include:my-card>

You can use directories within components to group your components. For example, components/forms/field.html:

<include:forms:field ... />

You can use named {% contents %} blocks, just like with the includecontents tag.

Some HTML formatters (like prettier) insist on quoting HTML attribute values. You can wrap the string contents in {{ }} to still read this as a template variable rather than a string:

<include:my-card title="{{ mytitle }}" />

You can also use short-hand syntax for HTML attributes when the attribute name matches the variable name:

<include:my-card {title} />

Component Props

You can define the required or default props of the component in a comment at the top of its template that begins with props (or def to match what JinjaX uses). An exception will be raised if a required prop is not provided.

Any other attributes passed to the component that are not listed in this definition will be added to an attrs context variable that can render them as HTML attributes.

{# props #}
<div {{ attrs }}>
  {{ contents }}
</div>

You can also provide default values for these attributes via the {% attrs %} template tag.

{# props title, large=False #}

<div {% attrs class="card" %}>
...

This example component above would require a title attribute and allow an optional large attribute. Any other attributes will be rendered on the div, with a default class of card if you don't specify a class attribute.

If you want to provide multiple groups of undefined attributes, you can use group.name as the format. Then render them with {{ attrs.group }} (or {% attrs.group %} if you want fallback values).

For example to call a component like this:

<include:form-field label="Name" name="first_name" value="John" input.class="wide"></include:form-field>

It could be defined like this:

{# props value, label="" #}

<div {% attrs class="field" %}>
  {% if label %}{{ '<label>'|safe }}{% endif %}
  {{ label }}
  <input {% attrs.input type="text" value=value %}>
  {% if label %}{{ '</label>'|safe }}{% endif %}
</div>

Kebab-cased props

Non-defined props can be "kebab-cased", for example:

<include:example my-prop="value">

To access a kebab-cased prop to a via the attrs variable, use its CamelCase equivalent. The {% attrs %} tag works with kebab-case fine though::

{# props #}

{% attrs my-prop="fallback" %}

{% if attrs.myProp %}
my-prop is explicitly set to {{ attrs.myProp }}
{% endif %}

Extended / conditional classes

Prepend your class list with "& " to have it extended rather than replaced:

{% attrs class="lg" %}        {# sets default class attribute to "lg" but can be overridden #}
{% attrs class="& lg p-3" %}  {# always add 'lg p-3' classes #}

You can provide conditional classes for the class attribute using the svelte class directive format:

{# props large=False #}

{% attrs class:lg=large %} {# adds 'lg' class if large prop is truthy #}
{% attrs class:lg %}       {# always adds 'lg' class #}

You can use this same conditional format on the component attributes directly:

<include:my-card title="Hello" class:lg={{ is_large }}> 
  <p>World</p>
</include:my-card>

Conditional classes in tailwindcss

Add this transform in your tailwind.config.js so that Tailwind picks up the Svelte-like class directives:

/** @type {import('tailwindcss').Config} */
module.exports = {
  content: {
    files: ["**/*.{html,js}", "!node_modules"],
    transform: {
      // Also handle Svelte-like class:class-name directives
      html: (content) => content.replace(/(\w):([-\w]+)/g, '$1 "$2" '),
    },
  },
  ...

Prettier formatting

While not part of this package, django-includecontents plays very well with the prettier-plugin-jinja-template plugin for Prettier. This plugin can provide consistent formatting for your Django (and Jinja, obviously) templates.

First install it with npm install --save-dev prettier-plugin-jinja-template.

Then create a .prettierrc file in your project root with the following content:

{
  "plugins": ["prettier-plugin-jinja-template"],
  "overrides": [
    {
      "files": ["**/{templates,jinja2}/**/*.html"],
      "options": {
        "parser": "jinja-template"
      }
    }
  ]
}

VScode formatting

To use this Prettier formatting within VScode, use the following two extensions:

• Django
• Prettier - Code formatter

Add this to your settings (Ctrl-P, paste >Preferences: Open Workspace Settings (JSON)):

{
  "[django-html]": {
    "editor.formatOnSave": true,
    "editor.defaultFormatter": "esbenp.prettier-vscode"
  },
}