From 16ffe5e31f80058389139fe5dae5184cc22319a6 Mon Sep 17 00:00:00 2001
From: Evan Heidtmann <evan.heidtmann@gmail.com>
Date: Thu, 26 Feb 2015 08:34:14 -0800
Subject: [PATCH 1/3] Add tests for callable attributes raising exceptions

---
 tests/test_fields.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tests/test_fields.py b/tests/test_fields.py
index ab3418bd6..7f5f81029 100644
--- a/tests/test_fields.py
+++ b/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):

From bdb73d558891192c96368d5ca2266327302dba54 Mon Sep 17 00:00:00 2001
From: Evan Heidtmann <evan.heidtmann@gmail.com>
Date: Thu, 26 Feb 2015 09:00:51 -0800
Subject: [PATCH 2/3] Avoid swallowing exceptions thrown in callable attributes

---
 rest_framework/fields.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index a5348922a..01e7c78c8 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -71,7 +71,11 @@ def get_attribute(instance, attrs):
         except ObjectDoesNotExist:
             return None
         if is_simple_callable(instance):
-            instance = instance()
+            try:
+                instance = instance()
+            except (AttributeError, KeyError) as exc:
+                raise ValueError('Exception raised in callable attribute "{0}"; original exception was: {1}'.format(attr, exc))
+
     return instance
 
 

From e6b06c34c1ee526b65c92b9071c47be2ddc668c4 Mon Sep 17 00:00:00 2001
From: Evan Heidtmann <evan.heidtmann@gmail.com>
Date: Thu, 26 Feb 2015 09:20:17 -0800
Subject: [PATCH 3/3] Add explanation for this exception mutation

---
 rest_framework/fields.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 01e7c78c8..f2791a13f 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -74,6 +74,9 @@ def get_attribute(instance, attrs):
             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