Use django's gettext in Svelte

Wrapper around django's JavaScript i18n features in Svelte.

Django docs: Using the JavaScript translation catalog

In your rollup configuration:

import svelte from 'rollup-plugin-svelte';
import { writeGettextExtracts, gettextStringExtractor } from 'svelte-django-gettext';

export default {
    input: 'app.js',
    output: {...},
    plugins: [
        svelte({
            preprocessors: {
                markup: gettextStringExtractor
            }
        }),
        ...

        writeGettextExtracts('js/_svelte_django_extracted_messages.js'),
    ]
}

In your application:

<script>
import gettext from 'svelte-django-gettext';

</script>

<h1>{gettext('hello')}</h1>

Make sure the page loads the generated catalog, from a django template: <script src="{% url 'javascript-catalog' %}"></script>. If this is not the case, all functions will just return their message id.

How it works:

Django's ./manage.py makemessages cannot parse .svelte files to extract gettext() calls. A rollup plugin extracts all gettext() calls and outputs _svelte_django_extracted_messages.js, containh contains gettext calls extracted from your .svelte files.

This file should be added to .gitignore, but is readable by django's magemessages management command.