Merge pull request #2608 from ezheidtmann/dont-swallow-errors-in-callable-sources

Dont swallow errors in callable sources

rest_framework/fields.py

@@ -71,7 +71,14 @@ def get_attribute(instance, attrs):
         except ObjectDoesNotExist:
             return None
         if is_simple_callable(instance):
-            instance = instance()
+            try:
+                instance = instance()
+            except (AttributeError, KeyError) as exc:
+                # If we raised an Attribute or KeyError here it'd get treated
+                # as an omitted field in `Field.get_attribute()`. Instead we
+                # raise a ValueError to ensure the exception is not masked.
+                raise ValueError('Exception raised in callable attribute "{0}"; original exception was: {1}'.format(attr, exc))
+
     return instance
 
 

tests/test_fields.py

@@ -93,6 +93,31 @@ class TestSource:
             "same as the field name. Remove the `source` keyword argument."
         )
 
+    def test_callable_source(self):
+        class ExampleSerializer(serializers.Serializer):
+            example_field = serializers.CharField(source='example_callable')
+
+        class ExampleInstance(object):
+            def example_callable(self):
+                return 'example callable value'
+
+        serializer = ExampleSerializer(ExampleInstance())
+        assert serializer.data['example_field'] == 'example callable value'
+
+    def test_callable_source_raises(self):
+        class ExampleSerializer(serializers.Serializer):
+            example_field = serializers.CharField(source='example_callable', read_only=True)
+
+        class ExampleInstance(object):
+            def example_callable(self):
+                raise AttributeError('method call failed')
+
+        with pytest.raises(ValueError) as exc_info:
+            serializer = ExampleSerializer(ExampleInstance())
+            serializer.data.items()
+
+        assert 'method call failed' in str(exc_info.value)
+
 
 class TestReadOnly:
     def setup(self):