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" %}{% endcomponent %}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!
Version 0.67 CHANGED the default way how context variables are resolved in slots. See the documentation for more details.
🚨📢 Version 0.5 CHANGES THE SYNTAX for components. component_block is now component, and component blocks need an ending endcomponent tag. The new python manage.py upgradecomponent command can be used to upgrade a directory (use --path argument to point to each dir) of components to the new syntax automatically.
This change is done to simplify the API in anticipation of a 1.0 release of django_components. After 1.0 we intend to be stricter with big changes like this in point releases.
Version 0.34 adds components as views, which allows you to handle requests and render responses from within a component. See the documentation for more details.
Version 0.28 introduces 'implicit' slot filling and the default option for slot tags.
Version 0.27 adds a second installable app: django_components.safer_staticfiles. It provides the same behavior as django.contrib.staticfiles but with extra security guarantees (more info below in Security Notes).
Version 0.26 changes the syntax for {% slot %} tags. From now on, we separate defining a slot ({% slot %}) from filling a slot with content ({% fill %}). This means you will likely need to change a lot of slot tags to fill. We understand this is annoying, but it's the only way we can get support for nested slots that fill in other slots, which is a very nice featuPpre to have access to. Hoping that this will feel worth it!
Version 0.22 starts autoimporting all files inside components subdirectores, to simplify setup. An existing project might start to get AlreadyRegistered-errors because of this. To solve this, either remove your custom loading of components, or set "autodiscover": False in settings.COMPONENTS.
Version 0.17 renames Component.context and Component.template to get_context_data and get_template_name. The old methods still work, but emit a deprecation warning. This change was done to sync naming with Django's class based views, and make using django-components more familiar to Django users. Component.context and Component.template will be removed when version 1.0 is released.
You are advised to read this section before using django-components in production.
Components can be organized however you prefer. That said, our prefered way is to keep the files of a component close together by bundling them in the same directory. This means that files containing backend logic, such as Python modules and HTML templates, live in the same directory as static files, e.g. JS and CSS.
If your are using django.contrib.staticfiles to collect static files, no distinction is made between the different kinds of files. As a result, your Python code and templates may inadvertently become available on your static file server. You probably don't want this, as parts of your backend logic will be exposed, posing a potential security vulnerability.
As of v0.27, django-components ships with an additional installable app django_components.safer_staticfiles. It is a drop-in replacement for django.contrib.staticfiles. Its behavior is 100% identical except it ignores .py and .html files, meaning these will not end up on your static files server. To use it, add it to INSTALLED_APPS and remove django.contrib.staticfiles.
INSTALLED_APPS = [
# 'django.contrib.staticfiles', # <-- REMOVE
'django_components',
'django_components.safer_staticfiles' # <-- ADD
]If you are on an older version of django-components, your alternatives are a) passing --ignore <pattern> options to the collecstatic CLI command, or b) defining a subclass of StaticFilesConfig.
Both routes are described in the official docs of the staticfiles app.
Install the app into your environment:
pip install django_components
Then add the app into INSTALLED_APPS in settings.py
INSTALLED_APPS = [
...,
'django_components',
]Modify TEMPLATES section of settings.py as follows:
- Remove
'APP_DIRS': True, - add
loaderstoOPTIONSlist and set it to following value:
TEMPLATES = [
{
...,
'OPTIONS': {
'context_processors': [
...
],
'loaders':[(
'django.template.loaders.cached.Loader', [
'django.template.loaders.filesystem.Loader',
'django.template.loaders.app_directories.Loader',
'django_components.template_loader.Loader',
]
)],
},
},
]Modify STATICFILES_DIRS (or add it if you don't have it) so django can find your static JS and CSS files:
STATICFILES_DIRS = [
...,
os.path.join(BASE_DIR, "components"),
]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',
]
},
},
]Read on to find out how to build your first component!
Django-components supports all supported combinations versions of Django and Python.
| Python version | Django version |
|---|---|
| 3.8 | 4.2 |
| 3.9 | 4.2 |
| 3.10 | 4.2, 5.0 |
| 3.11 | 4.2, 5.0 |
| 3.12 | 4.2, 5.0 |
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.
sampleproject/
├── calendarapp/
├── components/ 🆕
│ └── calendar/ 🆕
│ ├── calendar.py 🆕
│ ├── script.js 🆕
│ ├── style.css 🆕
│ └── template.html 🆕
├── sampleproject/
├── manage.py
└── requirements.txt
Start by creating empty files in the structure above.
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 [project root]/components/calendar/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 [project root]/components/calendar/script.js */
(function(){
if (document.querySelector(".calendar-component")) {
document.querySelector(".calendar-component").onclick = 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 [project root]/components/calendar/template.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 calendar.py in your component calendar directory. 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.
# In a file called [project root]/components/calendar/calendar.py
from django_components import component
@component.register("calendar")
class Calendar(component.Component):
# Templates inside `[your apps]/components` dir and `[project root]/components` dir will be automatically found. To customize which template to use based on context
# you can override def get_template_name() instead of specifying the below variable.
template_name = "calendar/template.html"
# This component takes one parameter, a date string to show in the template
def get_context_data(self, date):
return {
"date": date,
}
class Media:
css = "calendar/style.css"
js = "calendar/script.js"And voilá!! We've created our first component.
By default, the Python files in the components app are auto-imported in order to auto-register the components (e.g. components/button/button.py).
Autodiscovery occurs when Django is loaded, during the ready hook of the apps.py file.
If you are using autodiscovery, keep a few points in mind:
- Avoid defining any logic on the module-level inside the
componentsdir, that you would not want to run anyway. - Components inside the auto-imported files still need to be registered with
@component.register() - Auto-imported component files must be valid Python modules, they must use suffix
.py, and module name should follow PEP-8.
Autodiscovery can be disabled via in the settings.
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" %}{% endcomponent %}
{% component_js_dependencies %}
</body>
<html>The output from the above template will be:
<!DOCTYPE html>
<html>
<head>
<title>My example calendar</title>
<link href="/static/calendar/style.css" type="text/css" media="all" rel="stylesheet">
</head>
<body>
<div class="calendar-component">Today's date is <span>2015-06-19</span></div>
<script src="/static/calendar/script.js"></script>
</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.
Components can also be defined in a single file, which is useful for small components. To do this, you can use the template, js, and css class attributes instead of the template_name and Media. For example, here's the calendar component from above, defined in a single file:
# In a file called [project root]/components/calendar.py
from django_components import component
from django_components import types as t
@component.register("calendar")
class Calendar(component.Component):
def get_context_data(self, date):
return {
"date": date,
}
template: t.django_html = """
<div class="calendar-component">Today's date is <span>{{ date }}</span></div>
"""
css: t.css = """
.calendar-component { width: 200px; background: pink; }
.calendar-component span { font-weight: bold; }
"""
js: t.js = """
(function(){
if (document.querySelector(".calendar-component")) {
document.querySelector(".calendar-component").onclick = function(){ alert("Clicked calendar!"); };
}
})()
"""This makes it easy to create small components without having to create a separate template, CSS, and JS file.
Note that the t.django_html, t.css, and t.js types are used to specify the type of the template, CSS, and JS files, respectively. This is not necessary, but if you're using VSCode with the Python Inline Source Syntax Highlighting extension, it will give you syntax highlighting for the template, CSS, and JS.
New in version 0.26:
- The
slottag now serves only to declare new slots inside the component template.- To override the content of a declared slot, use the newly introduced
filltag instead.
- To override the content of a declared slot, use the newly introduced
- Whereas unfilled slots used to raise a warning, filling a slot is now optional by default.
- To indicate that a slot must be filled, the new
requiredoption should be added at the end of theslottag.
- To indicate that a slot must be filled, the new
Components support something called 'slots'. When a component is used inside another template, slots allow the parent template to override specific parts of the child component by passing in different content. This mechanism makes components more reusable and composable.
In the example below we introduce two block tags that work hand in hand to make this work. These are...
{% slot <name> %}/{% endslot %}: Declares a new slot in the component template.{% fill <name> %}/{% endfill %}: (Used inside acomponenttag pair.) Fills a declared slot with the specified content.
Let's update our calendar component to support more customization. We'll add slot tag pairs to its template, template.html.
<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 which slots you want to fill and where you want to use the defaults from the template. It looks like this:
{% component "calendar" date="2020-06-06" %}
{% fill "body" %}Can you believe it's already <span>{{ date }}</span>??{% endfill %}
{% endcomponent %}Since the header block is unspecified, it's taken from the base template. If you put this in a template, and pass in date=2020-06-06, this is what gets 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 in when you use a component. This makes for highly reusable components that can be used in different circumstances.
It can become tedious to use fill tags everywhere, especially when you're using a component that declares only one slot. To make things easier, slot tags can be marked with an optional keyword: default. When added to the end of the tag (as shown below), this option lets you pass filling content directly in the body of a component tag pair – without using a fill tag. Choose carefully, though: a component template may contain at most one slot that is marked as default. The default option can be combined with other slot options, e.g. required.
Here's the same example as before, except with default slots and implicit filling.
The template:
<div class="calendar-component">
<div class="header">
{% slot "header" %}Calendar header{% endslot %}
</div>
<div class="body">
{% slot "body" default %}Today's date is <span>{{ date }}</span>{% endslot %}
</div>
</div>Including the component (notice how the fill tag is omitted):
{% component "calendar" date="2020-06-06" %}
Can you believe it's already <span>{{ date }}</span>??
{% endcomponent %}The rendered result (exactly the same as before):
<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>You may be tempted to combine implicit fills with explicit fill tags. This will not work. The following component template will raise an error when compiled.
{# DON'T DO THIS #}
{% component "calendar" date="2020-06-06" %}
{% fill "header" %}Totally new header!{% endfill %}
Can you believe it's already <span>{{ date }}</span>??
{% endcomponent %}By contrast, it is permitted to use fill tags in nested components, e.g.:
{% component "calendar" date="2020-06-06" %}
{% component "beautiful-box" %}
{% fill "content" %} Can you believe it's already <span>{{ date }}</span>?? {% endfill %}
{% endcomponent %}
{% endcomponent %}This is fine too:
{% component "calendar" date="2020-06-06" %}
{% fill "header" %}
{% component "calendar-header" %}
Super Special Calendar Header
{% endcomponent %}
{% endfill %}
{% endcomponent %}New in version 0.34
Components can now be used as views. To do this, Component subclasses Django's View class. This means that you can use all of the methods of View in your component. For example, you can override get and post to handle GET and POST requests, respectively.
In addition, Component now has a render_to_response method that renders the component template based on the provided context and slots' data and returns an HttpResponse object.
Here's an example of a calendar component defined as a view:
# In a file called [project root]/components/calendar.py
from django_components import component
@component.register("calendar")
class Calendar(component.Component):
template = """
<div class="calendar-component">
<div class="header">
{% slot "header" %}{% endslot %}
</div>
<div class="body">
Today's date is <span>{{ date }}</span>
</div>
</div>
"""
def get(self, request, *args, **kwargs):
context = {
"date": request.GET.get("date", "2020-06-06"),
}
slots = {
"header": "Calendar header",
}
return self.render_to_response(context, slots)Then, to use this component as a view, you should create a urls.py file in your components directory, and add a path to the component's view:
# In a file called [project root]/components/urls.py
from django.urls import path
from calendar import Calendar
urlpatterns = [
path("calendar/", Calendar.as_view()),
]Remember to add __init__.py to your components directory, so that Django can find the urls.py file.
Finally, include the component's urls in your project's urls.py file:
# In a file called [project root]/urls.py
from django.urls import include, path
urlpatterns = [
path("components/", include("components.urls")),
]Note: slots content are automatically escaped by default to prevent XSS attacks. To disable escaping, set escape_slots_content=False in the render_to_response method. If you do so, you should make sure that any content you pass to the slots is safe, especially if it comes from user input.
If you're planning on passing an HTML string, check Django's use of format_html and mark_safe.
Certain properties of a slot can be accessed from within a 'fill' context. They are provided as attributes on a user-defined alias of the targeted slot. For instance, let's say you're filling a slot called 'body'. To access properties of this slot, alias it using the 'as' keyword to a new name -- or keep the original name. With the new slot alias, you can call <alias>.default to insert the default content.
{% component "calendar" date="2020-06-06" %}
{% fill "body" as "body" %}{{ body.default }}. Have a great day!{% endfill %}
{% endcomponent %}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>Added in version 0.26.
In certain circumstances, you may want the behavior of slot filling to depend on whether or not a particular slot is filled.
For example, suppose we have the following component template:
<div class="frontmatter-component">
<div class="title">
{% slot "title" %}Title{% endslot %}
</div>
<div class="subtitle">
{% slot "subtitle" %}{# Optional subtitle #}{% endslot %}
</div>
</div>By default the slot named 'subtitle' is empty. Yet when the component is used without explicit fills, the div containing the slot is still rendered, as shown below:
<div class="frontmatter-component">
<div class="title">
Title
</div>
<div class="subtitle">
</div>
</div>This may not be what you want. What if instead the outer 'subtitle' div should only be included when the inner slot is in fact filled?
The answer is to use the {% if_filled <name> %} tag. Together with {% endif_filled %},
these define a block whose contents will be rendered only if the component slot with
the corresponding 'name' is filled.
This is what our example looks like with an 'if_filled' tag.
<div class="frontmatter-component">
<div class="title">
{% slot "title" %}Title{% endslot %}
</div>
{% if_filled "subtitle" %}
<div class="subtitle">
{% slot "subtitle" %}{# Optional subtitle #}{% endslot %}
</div>
{% endif_filled %}
</div>Just as Django's builtin 'if' tag has 'elif' and 'else' counterparts, so does 'if_filled' include additional tags for more complex branching. These tags are 'elif_filled' and 'else_filled'. Here's what our example looks like with them.
<div class="frontmatter-component">
<div class="title">
{% slot "title" %}Title{% endslot %}
</div>
{% if_filled "subtitle" %}
<div class="subtitle">
{% slot "subtitle" %}{# Optional subtitle #}{% endslot %}
</div>
{% elif_filled "title" %}
...
{% else_filled %}
...
{% endif_filled %}
</div>Sometimes you're not interested in whether a slot is filled, but rather that it isn't. To negate the meaning of 'if_filled' in this way, an optional boolean can be passed to the 'if_filled' and 'elif_filled' tags.
In the example below we use False to indicate that the content should be rendered
only if the slot 'subtitle' is not filled.
{% if_filled subtitle False %}
<div class="subtitle">
{% slot "subtitle" %}{% endslot %}
</div>
{% endif_filled %}ComponentDependencyMiddleware is a Django middleware designed to manage and inject CSS/JS dependencies for rendered components dynamically. It ensures that only the necessary stylesheets and scripts are loaded in your HTML responses, based on the components used in your Django templates.
To set it up, add the middleware to your MIDDLEWARE in settings.py:
MIDDLEWARE = [
# ... other middleware classes ...
'django_components.middleware.ComponentDependencyMiddleware'
# ... other middleware classes ...
]Then, enable RENDER_DEPENDENCIES in setting.py:
COMPONENTS = {
"RENDER_DEPENDENCIES": True,
# ... other component settings ...
}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 %} tag):
{% component "calendar" date="2015-06-19" only %}{% endcomponent %}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.
You can also set context_behavior to isolated to make all components isolated by default. This is useful if you want to make sure that components don't accidentally access the outer context.
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 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",
],
}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 = {
"autodiscover": False,
}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,
}If you'd like to prevent components from accessing the outer context by default, you can set the context_behavior setting to isolated. This is useful if you want to make sure that components don't accidentally access the outer context.
COMPONENTS = {
"context_behavior": "isolated",
}What variables should be available from inside a component slot?
By default, variables inside component slots are preferentially taken from the root context. This is similar to how Vue renders slots, except that, if variable is not found in the root, then the surrounding context is searched too.
You can change this with the slot_contet_behavior setting. Options are:
"prefer_root"- Default - as described above"isolated"- Same behavior as Vue - variables are taken ONLY from the root context"allow_override"- slot context variables are taken from its surroundings (default before v0.67)
COMPONENTS = {
"slot_context_behavior": "isolated",
}For further details and examples, see SlotContextBehavior.
Django components supports logging with Django. This can help with troubleshooting.
To configure logging for Django components, set the django_components logger in LOGGING in settings.py (below).
Also see the settings.py file in sampleproject for a real-life example.
import logging
import sys
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
"handlers": {
"console": {
'class': 'logging.StreamHandler',
'stream': sys.stdout,
},
},
"loggers": {
"django_components": {
"level": logging.DEBUG,
"handlers": ["console"],
},
},
}You can use the built-in management command startcomponent to create a django component. The command accepts the following arguments and options:
-
name: The name of the component to create. This is a required argument. -
--path: The path to the components directory. This is an optional argument. If not provided, the command will use theBASE_DIRsetting from your Django settings. -
--js: The name of the JavaScript file. This is an optional argument. The default value isscript.js. -
--css: The name of the CSS file. This is an optional argument. The default value isstyle.css. -
--template: The name of the template file. This is an optional argument. The default value istemplate.html. -
--force: This option allows you to overwrite existing files if they exist. This is an optional argument. -
--verbose: This option allows the command to print additional information during component creation. This is an optional argument. -
--dry-run: This option allows you to simulate component creation without actually creating any files. This is an optional argument. The default value isFalse.
To use the command, run the following command in your terminal:
python manage.py startcomponent <name> --path <path> --js <js_filename> --css <css_filename> --template <template_filename> --force --verbose --dry-runReplace <name>, <path>, <js_filename>, <css_filename>, and <template_filename> with your desired values.
Here are some examples of how you can use the command:
To create a component with the default settings, you only need to provide the name of the component:
python manage.py startcomponent my_componentThis will create a new component named my_component in the components directory of your Django project. The JavaScript, CSS, and template files will be named script.js, style.css, and template.html, respectively.
You can also create a component with custom settings by providing additional arguments:
python manage.py startcomponent new_component --path my_components --js my_script.js --css my_style.css --template my_template.htmlThis will create a new component named new_component in the my_components directory. The JavaScript, CSS, and template files will be named my_script.js, my_style.css, and my_template.html, respectively.
If you want to overwrite an existing component, you can use the --force option:
python manage.py startcomponent my_component --forceThis will overwrite the existing my_component if it exists.
If you want to simulate the creation of a component without actually creating any files, you can use the --dry-run option:
python manage.py startcomponent my_component --dry-runThis will simulate the creation of my_component without creating any files.
One of our goals with django-components is to make it easy to share components between projects. If you have a set of components that you think would be useful to others, please open a pull request to add them to the list below.
- django-htmx-components: A set of components for use with htmx. Try out the live demo.
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.gitTo quickly run the tests install the local dependencies by running:
pip install -r requirements-dev.txtNow you can run the tests to make sure everything works as expected:
pytestThe library is also tested across many versions of Python and Django. To run tests that way:
pyenv install -s 3.8
pyenv install -s 3.9
pyenv install -s 3.10
pyenv install -s 3.11
pyenv install -s 3.12
pyenv local 3.8 3.9 3.10 3.11 3.12
tox -pHow do you check that your changes to django-components project will work in an actual Django project?
Use the sampleproject demo project to validate the changes:
-
Navigate to sampleproject directory:
cd sampleproject -
Install dependencies from the requirements.txt file:
pip install -r requirements.txt
-
Link to your local version of django-components:
pip install -e ..
NOTE: The path (in this case
..) must point to the directory that has thesetup.pyfile. -
Start Django server
python manage.py runserver
Once the server is up, it should be available at http://127.0.0.1:8000.
To display individual components, add them to the urls.py, like in the case of http://127.0.0.1:8000/greeting
-
Flow starts when a template string is being parsed into Django Template instance.
-
When a
{% component %}template tag is encountered, its body is searched for all{% fill %}nodes (explicit or implicit). and this is attached to the createdComponentNode.See the implementation of
componenttemplate tag for details. -
Template rendering is a separate action from template parsing. When the template is being rendered, the
ComponentNodecreates an instance of theComponentclass and passes it the slot fills.It's at this point when
Component.renderis called, and the slots are rendered.