Make model serialize/deserialize methods public. (#860)

Author: jpinner-lyft

docs/release_notes.rst

@@ -21,7 +21,8 @@ Items written using other formats must be rewritten before upgrading.
 
 ** Model Serialization **
 
-The ``Model._serialize`` method has changed and now only returns a dictionary of the DynamoDB attribute values.
+THe ``Model`` class now includes public methods for serializing and deserializing its attributes.
+``Model.serialize`` and ``Model.deserialize`` convert the model to/from a dictionary of DynamoDB attribute values.
 
 Other changes in this release:
 

pynamodb/attributes.py

@@ -341,7 +341,7 @@ def _set_attributes(self, **attributes: Attribute) -> None:
                 raise ValueError("Attribute {} specified does not exist".format(attr_name))
             setattr(self, attr_name, attr_value)
 
-    def _serialize(self, null_check=True) -> Dict[str, Dict[str, Any]]:
+    def serialize(self, null_check=True) -> Dict[str, Dict[str, Any]]:
         """
         Serialize attribute values for DynamoDB
         """
@@ -359,7 +359,7 @@ def _serialize(self, null_check=True) -> Dict[str, Dict[str, Any]]:
                 attribute_values[attr.attr_name] = {attr.attr_type: attr_value}
         return attribute_values
 
-    def _deserialize(self, attribute_values: Dict[str, Dict[str, Any]]) -> None:
+    def deserialize(self, attribute_values: Dict[str, Dict[str, Any]]) -> None:
         """
         Sets attributes sent back from DynamoDB on this object
         """
@@ -917,7 +917,7 @@ def serialize(self, values):
                         setattr(instance, name, values[name])
                 values = instance
 
-            return values._serialize()
+            return AttributeContainer.serialize(values)
 
         # Continue to serialize NULL values in "raw" map attributes for backwards compatibility.
         # This special case behavior for "raw" attributes should be removed in the future.
@@ -948,7 +948,7 @@ def deserialize(self, values):
                     discriminator_value = discriminator_attr.get_value(discriminator_attribute_value)
                     cls = discriminator_attr.deserialize(discriminator_value)
             instance = cls()
-            instance._deserialize(values)
+            AttributeContainer.deserialize(instance, values)
             return instance
 
         return {

pynamodb/models.py

@@ -120,7 +120,7 @@ def commit(self) -> None:
         delete_items = []
         for item in self.pending_operations:
             if item['action'] == PUT:
-                put_items.append(item['item']._serialize())
+                put_items.append(item['item'].serialize())
             elif item['action'] == DELETE:
                 delete_items.append(item['item']._get_keys())
         self.pending_operations = []
@@ -414,7 +414,7 @@ def update(self, actions: Sequence[Action], condition: Optional[Condition] = Non
         kwargs.update(actions=actions)
 
         data = self._get_connection().update_item(*args, **kwargs)
-        self._deserialize(data[ATTRIBUTES])
+        self.deserialize(data[ATTRIBUTES])
         return data
 
     def save(self, condition: Optional[Condition] = None) -> Dict[str, Any]:
@@ -443,7 +443,7 @@ def refresh(self, consistent_read: bool = False) -> None:
         item_data = attrs.get(ITEM, None)
         if item_data is None:
             raise self.DoesNotExist("This item does not exist in the table.")
-        self._deserialize(item_data)
+        self.deserialize(item_data)
 
     def get_operation_kwargs_from_instance(
         self,
@@ -532,7 +532,7 @@ def from_raw_data(cls: Type[_T], data: Dict[str, Any]) -> _T:
             raise ValueError("Received no data to construct object")
 
         model = cls(_user_instantiated=False)
-        model._deserialize(data)
+        model.deserialize(data)
         return model
 
     @classmethod
@@ -886,7 +886,7 @@ def _get_save_args(self, attributes=True, null_check=True):
         :param null_check: If True, then attributes are checked for null.
         """
         kwargs = {}
-        attribute_values = self._serialize(null_check)
+        attribute_values = self.serialize(null_check)
         hash_key_attribute = self._hash_key_attribute()
         hash_key = attribute_values.pop(hash_key_attribute.attr_name, {}).get(hash_key_attribute.attr_type)
         range_key = None

tests/test_discriminator.py

@@ -44,7 +44,7 @@ def test_serialize(self):
         dtm.hash_key = 'foo'
         dtm.value = StringValue(name='foo', value='Hello')
         dtm.values = [NumberValue(name='bar', value=5), RenamedValue(name='baz', value='World')]
-        assert dtm._serialize() == {
+        assert dtm.serialize() == {
             'hash_key': {'S': 'foo'},
             'value': {'M': {'cls': {'S': 'StringValue'}, 'name': {'S': 'foo'}, 'value': {'S': 'Hello'}}},
             'values': {'L': [

tests/test_model.py

@@ -1406,7 +1406,7 @@ def test_query(self):
             req.return_value = {'Count': len(items), 'ScannedCount': len(items), 'Items': items}
             queried = []
             for item in UserModel.query('foo', UserModel.user_id < 'id-1'):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
             self.assertTrue(len(queried) == len(items))
 
         with patch(PATCH_METHOD) as req:
@@ -1418,7 +1418,7 @@ def test_query(self):
             req.return_value = {'Count': len(items), 'ScannedCount': len(items), 'Items': items}
             queried = []
             for item in UserModel.query('foo', UserModel.user_id >= 'id-1'):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
             self.assertTrue(len(queried) == len(items))
 
         with patch(PATCH_METHOD) as req:
@@ -1430,7 +1430,7 @@ def test_query(self):
             req.return_value = {'Count': len(items), 'ScannedCount': len(items), 'Items': items}
             queried = []
             for item in UserModel.query('foo', UserModel.user_id <= 'id-1'):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
             self.assertTrue(len(queried) == len(items))
 
         with patch(PATCH_METHOD) as req:
@@ -1442,7 +1442,7 @@ def test_query(self):
             req.return_value = {'Count': len(items), 'ScannedCount': len(items), 'Items': items}
             queried = []
             for item in UserModel.query('foo', UserModel.user_id == 'id-1'):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
             self.assertTrue(len(queried) == len(items))
 
         with patch(PATCH_METHOD) as req:
@@ -1454,7 +1454,7 @@ def test_query(self):
             req.return_value = {'Count': len(items), 'ScannedCount': len(items), 'Items': items}
             queried = []
             for item in UserModel.query('foo', UserModel.user_id.startswith('id')):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
             self.assertTrue(len(queried) == len(items))
 
         with patch(PATCH_METHOD) as req:
@@ -1466,7 +1466,7 @@ def test_query(self):
             req.return_value = {'Count': len(items), 'ScannedCount': len(items), 'Items': items}
             queried = []
             for item in UserModel.query('foo'):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
             self.assertTrue(len(queried) == len(items))
 
         def fake_query(*args):
@@ -1512,7 +1512,7 @@ def fake_query(*args):
                     'foo',
                     UserModel.user_id.startswith('id'),
                     UserModel.email.contains('@') & UserModel.picture.exists() & UserModel.zip_code.between(2, 3)):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
             params = {
                 'KeyConditionExpression': '(#0 = :0 AND begins_with (#1, :1))',
                 'FilterExpression': '((contains (#2, :2) AND attribute_exists (#3)) AND #4 BETWEEN :3 AND :4)',
@@ -2066,7 +2066,7 @@ def test_index_queries(self):
             queried = []
 
             for item in IndexedModel.email_index.query('foo', filter_condition=IndexedModel.user_name.startswith('bar'), limit=2):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
 
             params = {
                 'KeyConditionExpression': '#0 = :0',
@@ -2104,7 +2104,7 @@ def test_index_queries(self):
                     'foo',
                     filter_condition=LocalIndexedModel.user_name.startswith('bar') & LocalIndexedModel.aliases.contains('baz'),
                     limit=1):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
 
             params = {
                 'KeyConditionExpression': '#0 = :0',
@@ -2145,7 +2145,7 @@ def test_index_queries(self):
                     'foo',
                     filter_condition=CustomAttrNameModel.overidden_user_name.startswith('bar'),
                     limit=2):
-                queried.append(item._serialize())
+                queried.append(item.serialize())
 
             params = {
                 'KeyConditionExpression': '#0 = :0',
@@ -2789,7 +2789,7 @@ def test_explicit_raw_map_serialize_pass(self):
         map_native = {'foo': 'bar'}
         map_serialized = {'M': {'foo': {'S': 'bar'}}}
         instance = ExplicitRawMapModel(map_attr=map_native)
-        serialized = instance._serialize()
+        serialized = instance.serialize()
         self.assertEqual(serialized['map_attr'], map_serialized)
 
     def test_raw_map_serialize_fun_one(self):
@@ -2805,7 +2805,7 @@ def test_raw_map_serialize_fun_one(self):
                'bool_type': {'BOOL': True}}}
 
         instance = ExplicitRawMapModel(map_attr=map_native)
-        serialized = instance._serialize()
+        serialized = instance.serialize()
         actual = serialized['map_attr']
         self.assertEqual(expected, actual)
 
@@ -2827,7 +2827,7 @@ def test_raw_map_deserializes(self):
             }
         }
         instance = ExplicitRawMapModel()
-        instance._deserialize({'map_attr': map_serialized})
+        instance.deserialize({'map_attr': map_serialized})
         actual = instance.map_attr
         for k, v in map_native.items():
             self.assertEqual(v, actual[k])
@@ -2866,7 +2866,7 @@ def test_raw_map_as_sub_map_serialize_pass(self):
                 map_field=map_native
             )
         )
-        serialized = instance._serialize()
+        serialized = instance.serialize()
         self.assertEqual(serialized['sub_attr']['M']['map_field'], map_serialized)
 
     def _get_raw_map_as_sub_map_test_data(self):