[1.8.x] Fixed #25683 -- Allowed ModelChoiceField(queryset=...) to accept Managers.

This fixes a regression from refs #25496.

Backport of 1155843a41af589a856efe8e671a796866430049 from master

1 files changed, 6 insertions, 4 deletions

diff --git a/django/forms/models.py b/django/forms/models.py
index 1036e9b288..384dddf242 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -1092,17 +1092,19 @@ class ModelChoiceIterator(object):
     def __iter__(self):
         if self.field.empty_label is not None:
             yield ("", self.field.empty_label)
-        method = 'all' if self.queryset._prefetch_related_lookups else 'iterator'
-        queryset = getattr(self.queryset, method)
+        queryset = self.queryset.all()
+        # Can't use iterator() when queryset uses prefetch_related()
+        if not queryset._prefetch_related_lookups:
+            queryset = queryset.iterator()
         if self.field.cache_choices:
             if self.field.choice_cache is None:
                 self.field.choice_cache = [
-                    self.choice(obj) for obj in queryset()
+                    self.choice(obj) for obj in queryset
                 ]
             for choice in self.field.choice_cache:
                 yield choice
         else:
-            for obj in queryset():
+            for obj in queryset:
                 yield self.choice(obj)
 
     def __len__(self):