deserialize map attributes correctly (#192)

Author: jmphilli

pynamodb/models.py

@@ -438,7 +438,7 @@ def from_raw_data(cls, data):
             attr = cls._get_attributes().get(name, None)
             if attr:
                 deserialized_attr = attr.deserialize(attr.get_value(value))
-                if isinstance(attr, MapAttribute):
+                if isinstance(attr, MapAttribute) and not type(attr) == MapAttribute:
                     deserialized_attr = type(attr)(**deserialized_attr)
                 kwargs[name] = deserialized_attr
         return cls(*args, **kwargs)

pynamodb/tests/data.py

@@ -1192,3 +1192,50 @@
         }
     }
 }
+
+EXPLICIT_RAW_MAP_MODEL_TABLE_DATA = {
+    'Table': {
+        'ItemCount': 0, 'TableName': 'ExplicitRawMapModel',
+        'ProvisionedThroughput': {
+            'ReadCapacityUnits': 2,
+            'WriteCapacityUnits': 2,
+            'NumberOfDecreasesToday': 0
+        },
+        'CreationDateTime': 1391471876.86,
+        'TableStatus': 'ACTIVE',
+        'AttributeDefinitions': [
+            {
+                'AttributeName': 'map_id',
+                'AttributeType': 'N'
+            },
+            {
+                'AttributeName': 'map_attr',
+                'AttributeType': 'M'
+            }
+        ],
+        'KeySchema': [
+            {
+                'AttributeName': 'map_id', 'KeyType': 'HASH'
+            }
+        ],
+        'TableSizeBytes': 0
+    }
+}
+
+EXPLICIT_RAW_MAP_MODEL_ITEM_DATA = {
+    'Item': {
+        'map_id': {
+            'N': '123',
+        },
+        'map_attr': {'M': {
+                'foo': {'S': 'bar'},
+                'num': {'N': '1'},
+                'bool_type': {'BOOL': True},
+                'other_b_type': {'BOOL': False},
+                'floaty': {'N': '1.2'},
+                'listy': {'L': [{'N': '1'}, {'N': '2'}, {'N': '3'}]},
+                'mapy': {'M': {'baz': {'S': 'bongo'}}}
+            }
+        }
+    }
+}

pynamodb/tests/test_model.py

@@ -43,7 +43,8 @@
     BOOLEAN_CONVERSION_MODEL_TABLE_DATA,
     BOOLEAN_CONVERSION_MODEL_NEW_STYLE_FALSE_ITEM_DATA, BOOLEAN_CONVERSION_MODEL_NEW_STYLE_TRUE_ITEM_DATA,
     BOOLEAN_CONVERSION_MODEL_OLD_STYLE_FALSE_ITEM_DATA, BOOLEAN_CONVERSION_MODEL_OLD_STYLE_TRUE_ITEM_DATA,
-    BOOLEAN_CONVERSION_MODEL_TABLE_DATA_OLD_STYLE, TREE_MODEL_TABLE_DATA, TREE_MODEL_ITEM_DATA
+    BOOLEAN_CONVERSION_MODEL_TABLE_DATA_OLD_STYLE, TREE_MODEL_TABLE_DATA, TREE_MODEL_ITEM_DATA,
+    EXPLICIT_RAW_MAP_MODEL_TABLE_DATA, EXPLICIT_RAW_MAP_MODEL_ITEM_DATA
 )
 
 if six.PY3:
@@ -400,7 +401,7 @@ class Meta:
 class ExplicitRawMapModel(Model):
     class Meta:
         table_name = 'ExplicitRawMapModel'
-
+    map_id = NumberAttribute(hash_key=True, default=123)
     map_attr = MapAttribute()
 
 
@@ -3076,3 +3077,34 @@ def test_raw_map_deserializes(self):
         for k,v in six.iteritems(map_native):
             self.assertEqual(v, actual[k])
 
+    def test_raw_map_from_raw_data_works(self):
+        map_native = {
+            'foo': 'bar', 'num': 1, 'bool_type': True,
+            'other_b_type': False, 'floaty': 1.2, 'listy': [1, 2, 3],
+            'mapy': {'baz': 'bongo'}
+        }
+        map_serialized = {
+
+            'M': {
+                'foo': {'S': 'bar'},
+                'num': {'N': 1},
+                'bool_type': {'BOOL': True},
+                'other_b_type': {'BOOL': False},
+                'floaty': {'N': 1.2},
+                'listy': {'L': [{'N': 1}, {'N': 2}, {'N': 3}]},
+                'mapy': {'M': {'baz': {'S': 'bongo'}}}
+            }
+        }
+        instance = ExplicitRawMapModel(map_attr=map_native, map_id=123)
+        fake_db = self.database_mocker(ExplicitRawMapModel,
+                                       EXPLICIT_RAW_MAP_MODEL_TABLE_DATA,
+                                       EXPLICIT_RAW_MAP_MODEL_ITEM_DATA,
+                                       'map_id', 'N',
+                                       '123')
+        with patch(PATCH_METHOD, new=fake_db) as req:
+            item = ExplicitRawMapModel.get(123)
+            actual = item.map_attr
+            for k, v in six.iteritems(map_native):
+                self.assertEqual(v, actual[k])
+
+