add 'cat_ids' management command

procat2/management/commands/cat_ids.py

@@ -0,0 +1,19 @@
+from django.core.management.base import BaseCommand, CommandError
+from procat2.models import Catalog
+
+
+class Command(BaseCommand):
+    help = 'Return material numbers for a catalog'
+
+    def add_arguments(self, parser):
+        parser.add_argument('cat_ids', nargs='+', type=int)
+
+    def handle(self, *args, **options):
+        for cat_id in options['cat_ids']:
+            try:
+                cat = Catalog.objects.get(pk=cat_id)
+            except Catalog.DoesNotExist:
+                raise CommandError('Catalog "%s" does not exist' % cat_id)
+
+            for id in cat.product_ids():
+                self.stdout.write(id)