Merge 64a6ac68a0 into e85ef3b479

rest_framework/fields.py

@@ -878,6 +878,10 @@ class DecimalField(WritableField):
     def __init__(self, max_value=None, min_value=None, max_digits=None, decimal_places=None, *args, **kwargs):
         self.max_value, self.min_value = max_value, min_value
         self.max_digits, self.decimal_places = max_digits, decimal_places
+        
+        if self.decimal_places:
+            self.empty = Decimal('0').quantize(Decimal('.%s1' % ('0' * (self.decimal_places - 1))))
+        
         super(DecimalField, self).__init__(*args, **kwargs)
 
         if max_value is not None:

rest_framework/tests/test_fields.py

@@ -638,6 +638,34 @@ class DecimalFieldTest(TestCase):
         self.assertFalse(DecimalSerializer(data={'decimal_field': '9900'}).is_valid())
         self.assertFalse(DecimalSerializer(data={'decimal_field': '9001.234'}).is_valid())
     
+    def test_decimal_is_not_quantized_when_decimal_places_is_none(self):
+        class LongDecimalFieldModel(models.Model):
+            decimal_field = models.DecimalField(max_digits=20, decimal_places=10, default=0)
+            
+        class DecimalSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = LongDecimalFieldModel
+            decimal_field = serializers.DecimalField(required=False, decimal_places=2)
+        
+        serializer = DecimalSerializer(data={})
+        
+        self.assertTrue(serializer.is_valid())
+        self.assertEqual(serializer.data['decimal_field'].as_tuple().exponent, 0)
+        
+    def test_decimal_is_quantized_when_decimal_places_is_provided(self):
+        class LongDecimalFieldModel(models.Model):
+            decimal_field = models.DecimalField(max_digits=20, decimal_places=10, default=0)
+            
+        class DecimalSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = LongDecimalFieldModel
+            decimal_field = serializers.DecimalField(required=False, decimal_places=2)
+        
+        serializer = DecimalSerializer(data={})
+        
+        self.assertTrue(serializer.is_valid())
+        self.assertEqual(serializer.data['decimal_field'].as_tuple().exponent, -2)
+    
     def test_raise_max_value(self):
         """
         Make sure max_value violations raises ValidationError