Django staticfiles JS-minifying storage backend

storage.py

from django.core.files.storage import FileSystemStorage
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, path):
        f = open(path, 'r+b')
        js_content = f.read()
        js_minified = minify(js_content)
        f.rewind()
        f.write(js_minified)
        f.close()

    def _save(self, name, content):
        name = super(StaticFileStorageAndJSMinifier, self)._save(name, content)

        if name.endswith('js'):
            full_path = self.path(name)
            self._minify_js(full_path)

        return name

Why write the file, read it, minify it and write it again?

This was quick and dirty coding for a proof of concept; I never actually used it. I believe you could easily run the super() call after the conditional, pass the "content" var into _minify_js() and return the minified content, and avoid the write/read/write mess.

Makes sense, Google took me here and I used it as a possible solution. Of course, since I have not used the storage API, I was not aware that the content parameter is actually a file-like object, not the file's content as a buffer. So the actual solution is a bit different. I will edit my gist to reflect that.

@jwineinger What is the license of this gist?