policies: Show grouped Dropdown for Target

passbook/lib/widgets.py

@@ -0,0 +1,28 @@
+"""Utility Widgets"""
+from functools import partial
+from itertools import groupby
+from operator import attrgetter
+
+from django.forms.models import ModelChoiceField, ModelChoiceIterator
+
+
+class GroupedModelChoiceIterator(ModelChoiceIterator):
+    """ModelChoiceField which groups objects by their verbose_name"""
+
+    def __iter__(self):
+        if self.field.empty_label is not None:
+            yield ("", self.field.empty_label)
+        queryset = self.queryset
+        # Can't use iterator() when queryset uses prefetch_related()
+        if not queryset._prefetch_related_lookups:
+            queryset = queryset.iterator()
+        # We can't use DB-level sorting as we sort by subclass
+        queryset = sorted(queryset, key=lambda x: x._meta.verbose_name)
+        for group, objs in groupby(queryset, key=lambda x: x._meta.verbose_name):
+            yield (group, [self.choice(obj) for obj in objs])
+
+
+class GroupedModelChoiceField(ModelChoiceField):
+    """ModelChoiceField which groups objects by their verbose_name"""
+
+    iterator = GroupedModelChoiceIterator