Include choices params even for non editable fields

The choices param can be usefull to populate list of possible values
and to instantiate a ChoiceField on the serializer, even when field is non_editable.

Relevant for the live doc and the OpenAPI integration.

Author: ticosax

rest_framework/utils/field_mapping.py

@@ -121,6 +121,9 @@ def get_field_kwargs(field_name, model_field):
     if model_field.null:
         kwargs['allow_null'] = True
 
+    if model_field.choices:
+        kwargs['choices'] = model_field.choices
+
     if isinstance(model_field, models.AutoField) or not model_field.editable:
         # If this field is read-only, then return early.
         # Further keyword arguments are not valid.
@@ -151,9 +154,7 @@ def get_field_kwargs(field_name, model_field):
         if model_field.allow_folders is not False:
             kwargs['allow_folders'] = model_field.allow_folders
 
-    if model_field.choices:
-        kwargs['choices'] = model_field.choices
-    else:
+    if not model_field.choices:
         # Ensure that max_value is passed explicitly as a keyword arg,
         # rather than as a validator.
         max_value = next((

tests/test_model_serializer.py

@@ -25,6 +25,7 @@
 
 from rest_framework import serializers
 from rest_framework.compat import postgres_fields
+from rest_framework.fields import ChoiceField
 
 from .models import NestedForeignKeySource
 
@@ -95,6 +96,7 @@ class FieldOptionsModel(models.Model):
 
 class ChoicesModel(models.Model):
     choices_field_with_nonstandard_args = models.DecimalField(max_digits=3, decimal_places=1, choices=DECIMAL_CHOICES, verbose_name='A label')
+    non_editable_choice_field = models.CharField(choices=COLOR_CHOICES, default=COLOR_CHOICES[0][0], editable=False)
 
 
 class Issue3674ParentModel(models.Model):
@@ -362,6 +364,16 @@ class Meta:
 
         ExampleSerializer()
 
+    def test_non_editable_choice_field(self):
+        class ExampleSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = ChoicesModel
+                fields = '__all__'
+
+        serializer = ExampleSerializer()
+        non_editable_choice_field = serializer.get_fields()["non_editable_choice_field"]
+        assert isinstance(non_editable_choice_field, ChoiceField)
+
 
 class TestDurationFieldMapping(TestCase):
     def test_duration_field(self):