Propagate 'default' from model_field to serializer field.

docs/api-guide/fields.md

@@ -68,6 +68,15 @@ When serializing the instance, default will be used if the object attribute or d
 
 Note that setting a `default` value implies that the field is not required. Including both the `default` and `required` keyword arguments is invalid and will raise an error.
 
+Notes regarding default value propagation from model to serializer:
+
+All the default values from model will pass as default to the serializer and the options method.
+
+If the default is callable then it will be propagated in serializer which is evaluated at each time but
+not in options method.
+
+If the value for given field is not given then default value will be present in the serializer and available in serializer's methods. Specified validation on given field will be evaluated on default value as that field will be present in the serializer.
+
 ### `allow_null`
 
 Normally an error will be raised if `None` is passed to a serializer field. Set this keyword argument to `True` if `None` should be considered a valid value.

rest_framework/metadata.py

@@ -11,6 +11,7 @@
 from django.utils.encoding import force_str
 
 from rest_framework import exceptions, serializers
+from rest_framework.fields import empty
 from rest_framework.request import clone_request
 from rest_framework.utils.field_mapping import ClassLookupDict
 
@@ -149,4 +150,7 @@ def get_field_info(self, field):
                 for choice_value, choice_name in field.choices.items()
             ]
 
+        if getattr(field, 'default', None) and field.default != empty and not callable(field.default):
+            field_info['default'] = field.default
+
         return field_info

rest_framework/utils/field_mapping.py

@@ -9,6 +9,7 @@
 from django.utils.text import capfirst
 
 from rest_framework.compat import postgres_fields
+from rest_framework.fields import empty
 from rest_framework.validators import UniqueValidator
 
 NUMERIC_FIELD_TYPES = (
@@ -127,6 +128,9 @@ def get_field_kwargs(field_name, model_field):
         kwargs['read_only'] = True
         return kwargs
 
+    if model_field.default is not None and model_field.default != empty and not callable(model_field.default):
+        kwargs['default'] = model_field.default
+
     if model_field.has_default() or model_field.blank or model_field.null:
         kwargs['required'] = False
 

tests/test_metadata.py

@@ -184,6 +184,135 @@ def get_serializer(self):
         assert response.status_code == status.HTTP_200_OK
         assert response.data == expected
 
+    def test_actions_with_default(self):
+        """
+        On generic views OPTIONS should return an 'actions' key with metadata
+        on the fields with default that may be supplied to PUT and POST requests.
+        """
+        class NestedField(serializers.Serializer):
+            a = serializers.IntegerField(default=2)
+            b = serializers.IntegerField()
+
+        class ExampleSerializer(serializers.Serializer):
+            choice_field = serializers.ChoiceField(['red', 'green', 'blue'], default='red')
+            integer_field = serializers.IntegerField(
+                min_value=1, max_value=1000, default=1
+            )
+            char_field = serializers.CharField(
+                min_length=3, max_length=40, default="example"
+            )
+            list_field = serializers.ListField(
+                child=serializers.ListField(
+                    child=serializers.IntegerField(default=1)
+                )
+            )
+            nested_field = NestedField()
+            uuid_field = serializers.UUIDField(label="UUID field")
+
+        class ExampleView(views.APIView):
+            """Example view."""
+            def post(self, request):
+                pass
+
+            def get_serializer(self):
+                return ExampleSerializer()
+
+        view = ExampleView.as_view()
+        response = view(request=request)
+        expected = {
+            'name': 'Example',
+            'description': 'Example view.',
+            'renders': [
+                'application/json',
+                'text/html'
+            ],
+            'parses': [
+                'application/json',
+                'application/x-www-form-urlencoded',
+                'multipart/form-data'
+            ],
+            'actions': {
+                'POST': {
+                    'choice_field': {
+                        'type': 'choice',
+                        'required': False,
+                        'read_only': False,
+                        'label': 'Choice field',
+                        "choices": [
+                            {'value': 'red', 'display_name': 'red'},
+                            {'value': 'green', 'display_name': 'green'},
+                            {'value': 'blue', 'display_name': 'blue'}
+                        ],
+                        'default': 'red'
+                    },
+                    'integer_field': {
+                        'type': 'integer',
+                        'required': False,
+                        'read_only': False,
+                        'label': 'Integer field',
+                        'min_value': 1,
+                        'max_value': 1000,
+                        'default': 1
+                    },
+                    'char_field': {
+                        'type': 'string',
+                        'required': False,
+                        'read_only': False,
+                        'label': 'Char field',
+                        'min_length': 3,
+                        'max_length': 40,
+                        'default': 'example'
+                    },
+                    'list_field': {
+                        'type': 'list',
+                        'required': True,
+                        'read_only': False,
+                        'label': 'List field',
+                        'child': {
+                            'type': 'list',
+                            'required': True,
+                            'read_only': False,
+                            'child': {
+                                'type': 'integer',
+                                'required': False,
+                                'read_only': False,
+                                'default': 1
+                            }
+                        }
+                    },
+                    'nested_field': {
+                        'type': 'nested object',
+                        'required': True,
+                        'read_only': False,
+                        'label': 'Nested field',
+                        'children': {
+                            'a': {
+                                'type': 'integer',
+                                'required': False,
+                                'read_only': False,
+                                'label': 'A',
+                                'default': 2
+                            },
+                            'b': {
+                                'type': 'integer',
+                                'required': True,
+                                'read_only': False,
+                                'label': 'B'
+                            }
+                        }
+                    },
+                    'uuid_field': {
+                        'type': 'string',
+                        'required': True,
+                        'read_only': False,
+                        'label': 'UUID field'
+                    }
+                }
+            }
+        }
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == expected
+
     def test_global_permissions(self):
         """
         If a user does not have global permissions on an action, then any

tests/test_model_serializer.py

@@ -173,7 +173,7 @@ class Meta:
             TestSerializer():
                 auto_field = IntegerField(read_only=True)
                 big_integer_field = IntegerField()
-                boolean_field = BooleanField(required=False)
+                boolean_field = BooleanField(default=False, required=False)
                 char_field = CharField(max_length=100)
                 comma_separated_integer_field = CharField(max_length=100, validators=[<django.core.validators.RegexValidator object>])
                 date_field = DateField()
@@ -182,7 +182,7 @@ class Meta:
                 email_field = EmailField(max_length=100)
                 float_field = FloatField()
                 integer_field = IntegerField()
-                null_boolean_field = BooleanField(allow_null=True, required=False)
+                null_boolean_field = BooleanField(allow_null=True, default=False, required=False)
                 positive_integer_field = IntegerField()
                 positive_small_integer_field = IntegerField()
                 slug_field = SlugField(allow_unicode=False, max_length=100)
@@ -210,7 +210,7 @@ class Meta:
                 length_limit_field = CharField(max_length=12, min_length=3)
                 blank_field = CharField(allow_blank=True, max_length=10, required=False)
                 null_field = IntegerField(allow_null=True, required=False)
-                default_field = IntegerField(required=False)
+                default_field = IntegerField(default=0, required=False)
                 descriptive_field = IntegerField(help_text='Some help text', label='A label')
                 choices_field = ChoiceField(choices=(('red', 'Red'), ('blue', 'Blue'), ('green', 'Green')))
                 text_choices_field = ChoiceField(choices=(('red', 'Red'), ('blue', 'Blue'), ('green', 'Green')))