Add support for native boolean attributes (#149)

LegacyBooleanAttribute also provided if previously using a boolean as a hash or range key. The new native class can deserialize legacy number type boolean attributes. A save will rewrite as a native boolean.

Author: jmphilli

pynamodb/attributes.py

@@ -7,7 +7,7 @@
 from delorean import Delorean, parse
 from pynamodb.constants import (
     STRING, NUMBER, BINARY, UTC, DATETIME_FORMAT, BINARY_SET, STRING_SET, NUMBER_SET,
-    DEFAULT_ENCODING
+    DEFAULT_ENCODING, BOOLEAN, ATTR_TYPE_MAP, NUMBER_SHORT
 )
 
 
@@ -58,6 +58,10 @@ def deserialize(self, value):
         """
         return value
 
+    def get_value(self, value):
+        serialized_dynamo_type = ATTR_TYPE_MAP[self.attr_type]
+        return value.get(serialized_dynamo_type)
+
 
 class SetMixin(object):
     """
@@ -186,18 +190,17 @@ def deserialize(self, value):
         return json.loads(value, strict=False)
 
 
-class BooleanAttribute(Attribute):
+class LegacyBooleanAttribute(Attribute):
     """
-    A class for boolean attributes
+    A class for legacy boolean attributes
 
-    This attribute type uses a number attribute to save space
+    Previous versions of this library serialized bools as numbers.
+    This class allows you to continue to use that functionality.
     """
+
     attr_type = NUMBER
 
     def serialize(self, value):
-        """
-        Encodes True as 1, False as 0
-        """
         if value is None:
             return None
         elif value:
@@ -206,12 +209,35 @@ def serialize(self, value):
             return json.dumps(0)
 
     def deserialize(self, value):
-        """
-        Encode
-        """
         return bool(json.loads(value))
 
 
+class BooleanAttribute(Attribute):
+    """
+    A class for boolean attributes
+    """
+    attr_type = BOOLEAN
+
+    def serialize(self, value):
+        if value is None:
+            return None
+        elif value:
+            return True
+        else:
+            return False
+
+    def deserialize(self, value):
+        return bool(value)
+
+    def get_value(self, value):
+        # we need this for legacy compatibility.
+        # previously, BOOL was serialized as N
+        value_to_deserialize = super(BooleanAttribute, self).get_value(value)
+        if value_to_deserialize is None:
+            value_to_deserialize = json.loads(value.get(NUMBER_SHORT, 0))
+        return value_to_deserialize
+
+
 class NumberSetAttribute(SetMixin, Attribute):
     """
     A number set attribute

pynamodb/compat.py

@@ -58,4 +58,4 @@ def assertListEqual(self, list1, list2, msg=None):
 
 class NullHandler(logging.Handler):
     def emit(self, record):
-        pass
+        pass

pynamodb/constants.py

@@ -81,6 +81,8 @@
 NUMBER_SET_SHORT = 'NS'
 BINARY_SHORT = 'B'
 BINARY_SET_SHORT = 'BS'
+BOOLEAN = 'BOOL'
+BOOLEAN_SHORT = 'BOOL'
 STRING = 'String'
 STRING_SET = 'StringSet'
 NUMBER = 'Number'
@@ -100,7 +102,8 @@
     NUMBER_SHORT: NUMBER,
     NUMBER_SET_SHORT: NUMBER_SET,
     BINARY_SHORT: BINARY,
-    BINARY_SET_SHORT: BINARY_SET
+    BINARY_SET_SHORT: BINARY_SET,
+    BOOLEAN: BOOLEAN_SHORT
 }
 # Constants needed for creating indexes
 LOCAL_SECONDARY_INDEX = 'LocalSecondaryIndex'

pynamodb/models.py

@@ -447,7 +447,7 @@ def from_raw_data(cls, data):
         for name, value in mutable_data.items():
             attr = cls._get_attributes().get(name, None)
             if attr:
-                kwargs[name] = attr.deserialize(value.get(ATTR_TYPE_MAP[attr.attr_type]))
+                kwargs[name] = attr.deserialize(attr.get_value(value))
         return cls(*args, **kwargs)
 
     @classmethod

pynamodb/tests/data.py

@@ -496,3 +496,105 @@
         }
     ]
 ]
+
+BOOLEAN_CONVERSION_MODEL_TABLE_DATA_OLD_STYLE = {
+    'Table': {
+        'ItemCount': 0, 'TableName': 'BooleanConversionTable',
+        'ProvisionedThroughput': {
+            'ReadCapacityUnits': 2,
+            'WriteCapacityUnits': 2,
+            'NumberOfDecreasesToday': 0
+        },
+        'CreationDateTime': 1391471876.86,
+        'TableStatus': 'ACTIVE',
+        'AttributeDefinitions': [
+            {
+                'AttributeName': 'user_name',
+                'AttributeType': 'S'
+            },
+            {
+                'AttributeName': 'is_human',
+                'AttributeType': 'N'
+            }
+        ],
+        'KeySchema': [
+            {
+                'AttributeName': 'user_name', 'KeyType': 'HASH'
+            }
+        ],
+        'TableSizeBytes': 0
+    }
+}
+
+BOOLEAN_CONVERSION_MODEL_TABLE_DATA = {
+    'Table': {
+        'ItemCount': 0, 'TableName': 'BooleanConversionTable',
+        'ProvisionedThroughput': {
+            'ReadCapacityUnits': 2,
+            'WriteCapacityUnits': 2,
+            'NumberOfDecreasesToday': 0
+        },
+        'CreationDateTime': 1391471876.86,
+        'TableStatus': 'ACTIVE',
+        'AttributeDefinitions': [
+            {
+                'AttributeName': 'user_name',
+                'AttributeType': 'S'
+            },
+            {
+                'AttributeName': 'is_human',
+                'AttributeType': 'BOOL'
+            }
+        ],
+        'KeySchema': [
+            {
+                'AttributeName': 'user_name', 'KeyType': 'HASH'
+            }
+        ],
+        'TableSizeBytes': 0
+    }
+}
+
+BOOLEAN_CONVERSION_MODEL_OLD_STYLE_TRUE_ITEM_DATA = {
+    'Item': {
+        'user_name': {
+            'S': 'justin'
+        },
+        'is_human': {
+            'N': '1'
+        }
+    }
+}
+
+BOOLEAN_CONVERSION_MODEL_OLD_STYLE_FALSE_ITEM_DATA = {
+    'Item': {
+        'user_name': {
+            'S': 'alf'
+        },
+        'is_human': {
+            'N': '0'
+        }
+    }
+}
+
+BOOLEAN_CONVERSION_MODEL_NEW_STYLE_TRUE_ITEM_DATA = {
+    'Item': {
+        'user_name': {
+            'S': 'justin'
+        },
+        'is_human': {
+            'BOOL': True
+        }
+    }
+}
+
+BOOLEAN_CONVERSION_MODEL_NEW_STYLE_FALSE_ITEM_DATA = {
+    'Item': {
+        'user_name': {
+            'S': 'alf'
+        },
+        'is_human': {
+            'BOOL': False
+        }
+    }
+}

pynamodb/tests/test_attributes.py

@@ -14,7 +14,7 @@
     BinarySetAttribute, BinaryAttribute, NumberSetAttribute, NumberAttribute,
     UnicodeAttribute, UnicodeSetAttribute, UTCDateTimeAttribute, BooleanAttribute,
     JSONAttribute, DEFAULT_ENCODING, NUMBER, STRING, STRING_SET, NUMBER_SET, BINARY_SET,
-    BINARY)
+    BINARY, BOOLEAN)
 
 
 class AttributeTestModel(Model):
@@ -380,7 +380,7 @@ def test_boolean_attribute(self):
         attr = BooleanAttribute()
         self.assertIsNotNone(attr)
 
-        self.assertEqual(attr.attr_type, NUMBER)
+        self.assertEqual(attr.attr_type, BOOLEAN)
         attr = BooleanAttribute(default=True)
         self.assertEqual(attr.default, True)
 
@@ -389,8 +389,8 @@ def test_boolean_serialize(self):
         BooleanAttribute.serialize
         """
         attr = BooleanAttribute()
-        self.assertEqual(attr.serialize(True), json.dumps(1))
-        self.assertEqual(attr.serialize(False), json.dumps(0))
+        self.assertEqual(attr.serialize(True), True)
+        self.assertEqual(attr.serialize(False), False)
         self.assertEqual(attr.serialize(None), None)
 
     def test_boolean_deserialize(self):
@@ -399,7 +399,9 @@ def test_boolean_deserialize(self):
         """
         attr = BooleanAttribute()
         self.assertEqual(attr.deserialize('1'), True)
-        self.assertEqual(attr.deserialize('0'), False)
+        self.assertEqual(attr.deserialize('0'), True)
+        self.assertEqual(attr.deserialize(True), True)
+        self.assertEqual(attr.deserialize(False), False)
 
 
 class JSONAttributeTestCase(TestCase):