django-components

A way to create simple reusable template components in Django.

It lets you create "template components", that contains both the template, the Javascript and the CSS needed to generate the front end code you need for a modern app. Components look like this:

{% component "calendar" date="2015-06-19" %}

And this is what gets rendered (plus the CSS and Javascript you've specified):

<div class="calendar-component">Today's date is <span>2015-06-19</span></div>

Read on to learn about the details!

Installation

Install the app into your environment:

pip install django_components

Then add the app into INSTALLED APPS in settings.py

INSTALLED_APPS = [
    ...,
    "django_components",
    ...
]

Optional

To avoid loading the app in each template using {% load django_components %}, you can add the tag as a 'builtin' in settings.py

TEMPLATES = [
    {
        ...,
        'OPTIONS': {
            'context_processors': [
                ...
            ],
            'builtins': [
                'django_components.templatetags.component_tags',
            ]
        },
    },
]

Contributors

_{Emil Stenström}

_{Ryan Hiebert}

_Rbeard0330

_{Bradley Stuart Kirton}

_{Dan Jacob}

_{Marc Fargas}

Compatiblity

Django-components supports all officially supported versions of Django and Python.

Python version	Django version
3.6	2.2, 3.0, 3.1, 3.2
3.7	2.2, 3.0, 3.1, 3.2
3.8	2.2, 3.0, 3.1, 3.2
3.9	2.2, 3.0, 3.1, 3.2

Create your first component

A component in django-components is the combination of four things: CSS, Javascript, a Django template, and some Python code to put them all together.

First you need a CSS file. Be sure to prefix all rules with a unique class so they don't clash with other rules.

/* In a file called style.css */
.calendar-component { width: 200px; background: pink; }
.calendar-component span { font-weight: bold; }

Then you need a javascript file that specifies how you interact with this component. You are free to use any javascript framework you want. A good way to make sure this component doesn't clash with other components is to define all code inside an anonymous function that calls itself. This makes all variables defined only be defined inside this component and not affect other components.

/* In a file called script.js */
(function(){
    $(".calendar-component").click(function(){ alert("Clicked calendar!"); })
})()

Now you need a Django template for your component. Feel free to define more variables like date in this example. When creating an instance of this component we will send in the values for these variables. The template will be rendered with whatever template backend you've specified in your Django settings file.

{# In a file called calendar.html #}
<div class="calendar-component">Today's date is <span>{{ date }}</span></div>

Finally, we use django-components to tie this together. Start by creating a file called components.py in any of your apps. It will be auto-detected and loaded by the app.

Inside this file we create a Component by inheriting from the Component class and specifying the context method. We also register the global component registry so that we easily can render it anywhere in our templates.

from django_components import component

@component.register("calendar")
class Calendar(component.Component):
    def context(self, date):
        return {
            "date": date,
        }

    def template(self, context):
        return "[your app]/components/calendar/calendar.html"

    class Media:
        css = '[your app]/components/calendar/calendar.css'
        js = '[your app]/components/calendar/calendar.js'

And voilá!! We've created our first component.

Use the component in a template

First load the component_tags tag library, then use the component_[js/css]_dependencies and component tags to render the component to the page.

{% load component_tags %}
<!DOCTYPE html>
<html>
<head>
    <title>My example calendar</title>
    {% component_css_dependencies %}
</head>
<body>
    {% component "calendar" date="2015-06-19" %}
    {% component_js_dependencies %}
</body>
<html>

The output from the above template will be:

<!DOCTYPE html>
<html>
<head>
    <title>My example calendar</title>
    <link href="style.css" type="text/css" media="all" rel="stylesheet">
    <script src="script.js"></script>
</head>
<body>
    <div class="calendar-component">Today's date is <span>2015-06-19</span></div>
</body>
<html>

This makes it possible to organize your front-end around reusable components. Instead of relying on template tags and keeping your CSS and Javascript in the static directory.

Using slots in templates

Components support something called slots. They work a lot like Django blocks, but only inside components you define. Let's update our calendar component to support more customization, by updating our calendar.html template:

<div class="calendar-component">
    <div class="header">
        {% slot "header" %}Calendar header{% endslot %}
    </div>
    <div class="body">
        {% slot "body" %}Today's date is <span>{{ date }}</span>{% endslot %}
    </div>
</div>

When using the component, you specify what slots you want to fill and where you want to use the defaults from the template. It looks like this:

{% component_block "calendar" date="2020-06-06" %}
    {% slot "body" %}Can you belive it's already <span>{{ date }}</span>??{% endslot %}
{% endcomponent_block %}

Since the header block is unspecified, it's taken from the base template. If you put this in a template, and send in date=2020-06-06, this is what's rendered:

<div class="calendar-component">
    <div class="header">
        Calendar header
    </div>
    <div class="body">
        Can you believe it's already <span>2020-06-06</span>??
    </div>
</div>

As you can see, component slots lets you write reusable containers, that you fill out when you use a component. This makes for highly reusable components, that can be used in different circumstances.

If you want to include a slot's default content while adding additional content, you can call slot.super to insert the base content, which works similarly to block.super.

{% component_block "calendar" date="2020-06-06" %}
    {% slot "body" %}{ slot.super }. Have a great day!{% endslot %}
{% endcomponent_block %}

Produces:

<div class="calendar-component">
    <div class="header">
        Calendar header
    </div>
    <div class="body">
        Today's date is <span>2020-06-06</span>.  Have a great day!
    </div>
</div>

Component context and scope

By default, components can access context variables from the parent template, just like templates that are included with the {% include %} tag. Just like with {% include %}, if you don't want the component template to have access to the parent context, add only to the end of the {% component %} (or {% component_block %} tag):

   {% component "calendar" date="2015-06-19" only %}

NOTE: {% csrf_token %} tags need access to the top-level context, and they will not function properly if they are rendered in a component that is called with the only modifier.

Components can also access the outer context in their context methods by accessing the property outer_context.

Available settings

All library settings are handled from a global COMPONENTS variable that is read from settings.py. By default you don't need it set, there are resonable defaults.

Configure the module where components are loaded from

Configure the location where components are loaded. To do this, add a COMPONENTS variable to you settings.py with a list of python paths to load. This allows you to build a structure of components that are independent from your apps.

COMPONENTS = {
    "libraries": [
        "mysite.components.forms",
        "mysite.components.buttons",
        "mysite.components.cards",
    ],
}

Disable autodiscovery

If you specify all the component locations with the setting above and have a lot of apps, you can (very) slightly speed things up by disabling autodiscovery.

COMPONENTS = {
    "autodiscovery": False,
}

Tune the template cache

Each time a template is rendered it is cached to a global in-memory cache (using Python's lru_cache decorator). This speeds up the next render of the component. As the same component is often used many times on the same page, these savings add up. By default the cache holds 128 component templates in memory, which should be enough for most sites. But if you have a lot of components, or if you are using the template method of a component to render lots of dynamic templates, you can increase this number. To remove the cache limit altogether and cache everything, set template_cache_size to None.

COMPONENTS = {
    "template_cache_size": 256,
}

Install locally and run the tests

Start by forking the project by clicking the Fork button up in the right corner in the GitHub . This makes a copy of the repository in your own name. Now you can clone this repository locally and start adding features:

git clone https://github.com/<your GitHub username>/django-components.git

To quickly run the tests install the local dependencies by running:

pip install -r requirements-dev.txt

Now you can run the tests to make sure everything works as expected:

pytest

The library is also tested across many versions of Python and Django. To run tests that way:

pyenv install 3.6.9
pyenv install 3.7.9
pyenv install 3.8.9
pyenv install 3.9.4
pyenv local 3.6.9 3.7.9 3.8.9 3.9.4
tox -p

License

hazho/django-components

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