[5.0.x] Refs #34899 -- Extracted Field.flatchoices to flatten_choices helper function.

Co-authored-by: Natalia Bidart <124304+nessita@users.noreply.github.com>

Backport of 74afcee234f8be989623ccc7c28b9fb97fb548f0 from main

1 files changed, 8 insertions, 13 deletions

diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index f15b5856bf..6174b7bc98 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -15,7 +15,11 @@ from django.db import connection, connections, router
 from django.db.models.constants import LOOKUP_SEP
 from django.db.models.query_utils import DeferredAttribute, RegisterLookupMixin
 from django.utils import timezone
-from django.utils.choices import CallableChoiceIterator, normalize_choices
+from django.utils.choices import (
+    CallableChoiceIterator,
+    flatten_choices,
+    normalize_choices,
+)
 from django.utils.datastructures import DictWrapper
 from django.utils.dateparse import (
     parse_date,
@@ -1080,19 +1084,10 @@ class Field(RegisterLookupMixin):
         """
         return str(self.value_from_object(obj))
 
-    def _get_flatchoices(self):
+    @property
+    def flatchoices(self):
         """Flattened version of choices tuple."""
-        if self.choices is None:
-            return []
-        flat = []
-        for choice, value in self.choices:
-            if isinstance(value, (list, tuple)):
-                flat.extend(value)
-            else:
-                flat.append((choice, value))
-        return flat
-
-    flatchoices = property(_get_flatchoices)
+        return list(flatten_choices(self.choices))
 
     def save_form_data(self, instance, data):
         setattr(instance, self.name, data)