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head-context

Easily manage your assets in meta tags (scripts, css, preload etc.) from anywhere in the template code (and outside).

Why

Imagine a form widget, which requires a heavy image processing library that we want to include ONLY IF the widget itself was rendered. Thanks to head-context you can specify what resources you need locally (in template fragments, widgets and so on) yet load them in the head section of your page with ease.

What does it do?

<!doctype html>
<html>
<head>
    <title>My Title!</title>
    <!-- this is where we want all our js/css rendered to be rendered -->
    {{ head_placeholder() }}
</head>
<body>
    {% include "my-cool-component.html" %}
</body>
</html>

And my-cool-component.html:

<!-- we can call these from anywhere and they will be automatically rendered in the right place! -->
{% do push_js('/static/cool-component.js', mode="async") %}
{% do push_css('/static/cool-component.css') %}
{% do push_preload('/static/some-image-we-need.png', 'image') %}
<div class="my-cool-component">
    <!-- ... --->
</div>

And that's pretty much it. You can push_js/push_css/push_preload from anywhere in the template (and even outside of templates) and it will be automatically attached to the page being rendered.

Features

  • Supports scripts, styles and preload directives
  • Works with Jinja2
  • Can be used from Python code too
    • simply use head_context.push_js/push_css/push_preload from Python code
    • it needs to run during template rendering though (otherwise it wouldn't make sense)
    • useful if you have form widget rendering written in Python for example
    • or basically any kind of rendering written in Python

Installation and setup

Simply install head-context package:

pip install head-context
# or with poetry
poetry add head-context

Add extension to the Jinja2 environment:

from jinja2 import Environment

env = Environment()
env.add_extension("head_context.jinja_ext.HeadContextExtension")

and that's it! From now on you can use push_css()/push_js()/push_preload() and head_placeholder().

Usage with Flask

To use this extension with Flask simply add it when configuring the app:

def create_app():
    app = Flask("app", __name__)
    app.jinja_env.add_extension("head_context.jinja_ext.HeadContextExtension")
    app.jinja_env.add_extension("jinja2.ext.do")
    
    return app

FAQ

Does this work with asyncio?

head-context uses contextvars under the hood, which are compatible with asyncio but it integrates with Jinja in a way that won't work with templates which use asyncio rendering. If you have any good ideas how to make it work a PR would be welcome.

Release files for head-context 0.1.1

For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.

Source distribution (sdist)

Source distribution for head-context 0.1.1
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head_context-0.1.1.tar.gz 5.6 kB Details

Built distribution (wheel)

Table of built distributions (wheels) for head-context 0.1.1
File Interpreter ABI Platform
head_context-0.1.1-py3-none-any.whl Python 3 none any Details

Total release size: 11.7 kB

Release files / head_context-0.1.1.tar.gz

Download URL head_context-0.1.1.tar.gz
Size 5.6 kB
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Size 6.0 kB
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