Cannot set String field to a dict anymore!

common/lib/xmodule/xmodule/tests/test_xml_module.py

@@ -188,6 +188,18 @@ def assertDeserializeEqual(field, expected, arg):
     assert_equals(expected, deserialize_field(field, arg))
 
 
+def assertDeserializeNonString(field):
+    """
+    Asserts input value is returned for None or something that is not a string.
+    """
+    assertDeserializeEqual(field, None, None)
+    assertDeserializeEqual(field, 3.14, 3.14)
+    assertDeserializeEqual(field, True, True)
+    assertDeserializeEqual(field, [10], [10])
+    assertDeserializeEqual(field, {}, {})
+    assertDeserializeEqual(field, [], [])
+
+
 class TestSerializeInteger(unittest.TestCase):
     """ Tests serialize/deserialize as related to Integer type. """
 
@@ -208,7 +220,7 @@ class TestSerializeInteger(unittest.TestCase):
 
     def test_deserialize_unsupported_types(self):
         assertDeserializeEqual(Integer(), '[3]', '[3]')
-        self.assertRaises(TypeError, deserialize_field, None)
+        assertDeserializeNonString(Integer())
 
 
 class FloatTest(unittest.TestCase):
@@ -235,7 +247,7 @@ class FloatTest(unittest.TestCase):
 
     def test_deserialize_unsupported_types(self):
         assertDeserializeEqual(Float(), '[3]', '[3]')
-        self.assertRaises(TypeError, deserialize_field, None)
+        assertDeserializeNonString(Float())
 
 
 class BooleanTest(unittest.TestCase):
@@ -264,8 +276,7 @@ class BooleanTest(unittest.TestCase):
         assertDeserializeEqual(Boolean(), 'fAlse', '"fAlse"')
         assertDeserializeEqual(Boolean(), "TruE", '"TruE"')
 
-    def test_deserialize_unsupported_types(self):
-        self.assertRaises(TypeError, deserialize_field, None)
+        assertDeserializeNonString(Boolean())
 
 
 class StringTest(unittest.TestCase):
@@ -286,7 +297,7 @@ class StringTest(unittest.TestCase):
         assertDeserializeEqual(String(), 'false', 'false')
         assertDeserializeEqual(String(), '2', '2')
         assertDeserializeEqual(String(), '[3]', '[3]')
-        self.assertRaises(TypeError, deserialize_field, None)
+        assertDeserializeNonString(String())
 
 
 class AnyTest(unittest.TestCase):
@@ -307,9 +318,7 @@ class AnyTest(unittest.TestCase):
         assertDeserializeEqual(Any(), '[', '[')
         assertDeserializeEqual(Any(), False, 'false')
         assertDeserializeEqual(Any(), 3.4, '3.4')
-
-    def test_deserialize_unsupported_types(self):
-        self.assertRaises(TypeError, deserialize_field, None)
+        assertDeserializeNonString(Any())
 
 
 class ListTest(unittest.TestCase):
@@ -330,7 +339,7 @@ class ListTest(unittest.TestCase):
         assertDeserializeEqual(List(), '3.4', '3.4')
         assertDeserializeEqual(List(), 'false', 'false')
         assertDeserializeEqual(List(), '2', '2')
-        self.assertRaises(TypeError, deserialize_field, None)
+        assertDeserializeNonString(List())
 
 
 class DateTest(unittest.TestCase):
@@ -342,9 +351,11 @@ class DateTest(unittest.TestCase):
     def test_deserialize(self):
         assertDeserializeEqual(Date(), '2012-12-31T23:59:59Z', "2012-12-31T23:59:59Z")
         assertDeserializeEqual(Date(), '2012-12-31T23:59:59Z', '"2012-12-31T23:59:59Z"')
+        assertDeserializeNonString(Date())
 
 
 class TimedeltaTest(unittest.TestCase):
+    """ Tests serialize/deserialize as related to Timedelta type. """
 
     def test_serialize(self):
         assertSerializeEqual('"1 day 12 hours 59 minutes 59 seconds"',
@@ -355,3 +366,4 @@ class TimedeltaTest(unittest.TestCase):
             '1 day 12 hours 59 minutes 59 seconds')
         assertDeserializeEqual(Timedelta(), '1 day 12 hours 59 minutes 59 seconds',
             '"1 day 12 hours 59 minutes 59 seconds"')
+        assertDeserializeNonString(Timedelta())

common/lib/xmodule/xmodule/xml_module.py

@@ -95,23 +95,28 @@ def deserialize_field(field, value):
     Note that this is not the same as the value returned by from_json, as model types typically store
     their value internally as JSON. By default, this method will return the result of calling json.loads
     on the supplied value, unless json.loads throws a TypeError, or the type of the value returned by json.loads
-    is not supported for this class (see 'is_type_supported'). In either of those cases, this method returns
+    is not supported for this class (from_json throws an Error). In either of those cases, this method returns
     the input value.
     """
     try:
         deserialized = json.loads(value)
-
         if deserialized is None:
             return deserialized
         try:
             field.from_json(deserialized)
             return deserialized
         except (ValueError, TypeError):
-            # Support older serialized forms by simply returning the String representation
+            # Support older serialized version, which was just a string, not result of json.dumps.
+            # If the deserialized version cannot be converted to the type (via from_json),
+            # just return the original value. For example, if a string value of '3.4' was
+            # stored for a String field (before we started storing the result of json.dumps),
+            # then it would be deserialized as 3.4, but 3.4 is not supported for a String
+            # field. Therefore field.from_json(3.4) will throw an Error, and we should
+            # actually return the original value of '3.4'.
             return value
 
     except (ValueError, TypeError):
-        # Support older serialized version, which was just the String (not the result of json.dumps).
+        # Support older serialized version.
         return value