Ensure read-only fields don't break with current HTML renderer behavior

rest_framework/fields.py

@@ -777,6 +777,7 @@ class IntegerField(WritableField):
     type_name = 'IntegerField'
     type_label = 'integer'
     form_field_class = forms.IntegerField
+    empty = 0
 
     default_error_messages = {
         'invalid': _('Enter a whole number.'),
@@ -808,6 +809,7 @@ class FloatField(WritableField):
     type_name = 'FloatField'
     type_label = 'float'
     form_field_class = forms.FloatField
+    empty = 0
 
     default_error_messages = {
         'invalid': _("'%s' value must be a float."),
@@ -828,6 +830,7 @@ class DecimalField(WritableField):
     type_name = 'DecimalField'
     type_label = 'decimal'
     form_field_class = forms.DecimalField
+    empty = Decimal('0')
 
     default_error_messages = {
         'invalid': _('Enter a number.'),

rest_framework/serializers.py

@@ -310,6 +310,8 @@ class BaseSerializer(WritableField):
         ret.fields = self._dict_class()
 
         for field_name, field in self.fields.items():
+            if field.read_only and obj is None:
+               continue
             field.initialize(parent=self, field_name=field_name)
             key = self.get_field_key(field_name)
             value = field.field_to_native(obj, field_name)

rest_framework/tests/test_serializer.py

@@ -159,8 +159,7 @@ class BasicTests(TestCase):
         expected = {
             'email': '',
             'content': '',
-            'created': None,
-            'sub_comment': ''
+            'created': None
         }
         self.assertEqual(serializer.data, expected)
 

rest_framework/tests/test_serializer_empty.py

@@ -0,0 +1,15 @@
+from django.test import TestCase
+from rest_framework import serializers
+
+
+class EmptySerializerTestCase(TestCase):
+    def test_empty_serializer(self):
+        class FooBarSerializer(serializers.Serializer):
+            foo = serializers.IntegerField()
+            bar = serializers.SerializerMethodField('get_bar')
+
+            def get_bar(self, obj):
+                return 'bar'
+
+        serializer = FooBarSerializer()
+        self.assertEquals(serializer.data, {'foo': 0})