DjHTML

A pure-Python Django/Jinja template indenter without dependencies.

DjHTML is a fully automatic template indenter that works with mixed HTML/CSS/Javascript templates that contain Django or Jinja template tags. It works similar to other code-formatting tools such as Black and interoperates nicely with pre-commit.

DjHTML is an indenter and not a formatter: it will only add/remove whitespace at the beginning of lines. It will not insert newlines or other characters. The goal is to correctly indent already well-structured templates, not to fix broken ones.

For example, consider the following incorrectly indented template:

<!doctype html>
<html>
    <body>
        {% block content %}
        Hello, world!
        {% endblock %}
        <script>
            $(function() {
            console.log('Hi mom!');
            });
        </script>
    </body>
</html>

This is what it will look like after processing by DjHTML:

<!doctype html>
<html>
    <body>
        {% block content %}
            Hello, world!
        {% endblock %}
        <script>
            $(function() {
                console.log('Hi mom!');
            });
        </script>
    </body>
</html>

Installation

Install DjHTML with the following command:

$ pip install djhtml

Usage

After installation you can indent templates using the djhtml command. The default is to read from standard in and to write the indented output to standard out. To modify the source file in-place, use the -i / --in-place option and specify a filename:

$ djhtml -i template.html
reindented template.html
1 template has been reindented.

Normally, the exit status of 0 means everything went well, regardless of whether any files were changed. If any errors were encountered, the exit status indicated the number of problematic files. However, when the option -c / --check is used, the exit status is the number of files that would have changed, but no changes are actually made.

All available options are:

-h / --help: show overview of available options
-i / --in-place: modify files in-place
-c / --check: don't modify files; the exit status is the number of files that would have changed
-q / --quiet: don't print any output
-t / --tabwidth: set tabwidth (default is 4)
-o / --output-file: write output to specified file

`fmt:off` and `fmt:on`

You can exclude specific lines from being processed with the {# fmt:off #} and {# fmt:on #} operators:

<div class="
    {# fmt:off #}
      ,-._|\
     /     .\
     \_,--._/
    {# fmt:on #}
"/>

Contents inside <pre> ... </pre>, , /* ... */, and {% comment %} ... {% endcomment %} tags are also ignored (depending on the current mode).

Modes

The indenter operates in one of three different modes:

DjHTML mode: the default mode. Invoked by using the djhtml command or the pre-commit hook.
DjCSS mode. Will be entered when a <style> tag is encountered in DjHTML mode. It can also be invoked directly with the command djcss.
DjJS mode. Will be entered when a <script> tag is encountered in DjHTML mode. It can also be invoked directly with the command djjs.

pre-commit configuration

The best way to use DjHTML is as a pre-commit hook, so all your HTML, CSS and JavaScript files will automatically be indented upon every commit.

First, install pre-commit:

$ pip install pre-commit
$ pre-commit install

Then, add the following to your .pre-commit-config.yaml:

repos:
- repo: https://github.com/rtts/djhtml
  rev: 'main'  # replace with the latest tag on GitHub
  hooks:
    - id: djhtml
    - id: djcss
    - id: djjs

If you want to limit the files these hooks operate on, you can use pre-commit mechanisms for filtering. For example:

- repo: https://github.com/rtts/djhtml
  rev: 'main'  # replace with the latest tag on GitHub
  hooks:
    - id: djhtml
      # Indent only HTML files in template directories
      files: .*/templates/.*\.html$
    - id: djcss
      # Run this hook only on SCSS files (CSS and SCSS is the default)
      types: [scss]
    - id: djjs
      # Exclude JavaScript files in vendor directories
      exclude: .*/vendor/.*

Finally, run pre-commit autoupdate to automatically replace main with the latest tag on GitHub, as recommended by pre-commit.

Now when you run git commit you will see something like the following output:

$ git commit

DjHTML...................................................................Failed
- hook id: djhtml
- files were modified by this hook

reindented template.html
1 template has been reindented.

To inspect the changes that were made, use git diff. If you are happy with the changes, you can commit them normally. If you are not happy, please do the following:

Run SKIP=djhtml git commit to commit anyway, skipping the djhtml hook.
Consider opening an issue with the relevant part of the input file that was incorrectly formatted, and an example of how it should have been formatted.

Your feedback for improving DjHTML is very welcome!

Development

Use your preferred system for setting up a virtualenv, docker environment, or whatever else, then run the following:

python -m pip install -e '.[dev]'
pre-commit install --install-hooks

Tests can then be run quickly in that environment:

python -m unittest discover -v

Or testing in all available supported environments and linting can be run with nox:

nox

rupertbaker/djhtml