Django staticfiles JS-minifying storage backend

storage.py

import os.path
from django.core.files.storage import FileSystemStorage
from django.core.files.base import ContentFile
from slimit import minify

class StaticFileStorageAndJSMinifier(FileSystemStorage):
    """
    A storage backend to be used by the staticfiles app -- STATICFILES_STORAGE
    setting. This backend operates just as a normal filesystem storage backend
    except when it detects a javascript file.
    
    After a javascript file is saved, we reopen the file, minify the contents
    and write back to the same place.  This allows the default storage
    behaviors for finding an unused path to work as defined in core.

    Only works in Django > 1.3 where the collectstatic management command
    actually uses the storage backend to save the file. In Django 1.3,
    collectstatic uses a filesystem copy for local storages, which bypasses
    the storage backend so we cannot hook into it to modify the files.
    """
    def _minify_js(self, content):
        return ContentFile(minify(content.read()))

    def _save(self, name, content):
        # TODO: minify css also!
        if os.path.splitext(name)[1] == '.js':
            try:
                content = self._minify_js(content)
            except:
                pass # Leave content untouched
        return super(StaticFileStorageAndJSMinifier, self)._save(name, content)

This fork has the benefit of not writing, reading, then re-writing the file contents. Also, since it does no writing directly, it can be adapted to a mixin that would work with other storage backends (like S3Storage).

@btimby What is the license of this gist?