Added unreferenced_files command.

This command lists every file under MEDIA_ROOT that isn't referenced in the database
in a FileField or subclass of FileField.

django_extensions/management/commands/unreferenced_files.py

@@ -0,0 +1,44 @@
+from collections import defaultdict
+import os
+from django.conf import settings
+from django.core.management.base import NoArgsCommand
+from django.db import models
+from django.db.models.loading import cache
+
+class Command(NoArgsCommand):
+    help = "Prints a list of all files in MEDIA_ROOT that are not referenced in the database."
+
+    def handle_noargs(self, **options):
+
+        if settings.MEDIA_ROOT == '':
+            print "MEDIA_ROOT is not set, nothing to do"
+            return
+
+        # Get a list of all files under MEDIA_ROOT
+        media = []
+        for root, dirs, files in os.walk(settings.MEDIA_ROOT):
+            for f in files:
+                media.append(os.path.abspath(os.path.join(root, f)))
+
+        # Get list of all fields (value) for each model (key)
+        # that is a FileField or subclass of a FileField
+        model_dict = defaultdict(list)
+        for app in cache.get_apps():
+            model_list = cache.get_models(app)
+            for model in model_list:
+                for field in model._meta.fields:
+                    if issubclass(field.__class__, models.FileField):
+                        model_dict[model].append(field)
+
+        # Get a list of all files referenced in the database
+        referenced = []
+        for model in model_dict.iterkeys():
+            all = model.objects.all().iterator()
+            for object in all:
+                for field in model_dict[model]:
+                    referenced.append(os.path.abspath(getattr(object, field.name).path))
+
+        # Print each file in MEDIA_ROOT that is not referenced in the database
+        for m in media:
+            if m not in referenced:
+                print m