Fixed #20430 - Enable iterable of iterables for model choices

Allows for any iterable, not just lists or tuples, to be used as
the inner item for a list of choices in a model.

1 files changed, 2 insertions, 2 deletions

diff --git a/django/core/management/validation.py b/django/core/management/validation.py
index 0f0eade569..2040a14582 100644
--- a/django/core/management/validation.py
+++ b/django/core/management/validation.py
@@ -118,8 +118,8 @@ def get_validation_errors(outfile, app=None):
                     e.add(opts, '"%s": "choices" should be iterable (e.g., a tuple or list).' % f.name)
                 else:
                     for c in f.choices:
-                        if not isinstance(c, (list, tuple)) or len(c) != 2:
-                            e.add(opts, '"%s": "choices" should be a sequence of two-tuples.' % f.name)
+                        if isinstance(c, six.string_types) or not is_iterable(c) or len(c) != 2:
+                            e.add(opts, '"%s": "choices" should be a sequence of two-item iterables (e.g. list of 2 item tuples).' % f.name)
             if f.db_index not in (None, True, False):
                 e.add(opts, '"%s": "db_index" should be either None, True or False.' % f.name)