Multiple attrs update

docs/conditional.rst

@@ -103,7 +103,7 @@ This example will update a `Thread` item, if the `forum_name` attribute equals '
 
 .. code-block:: python
 
-    thread_item.update_item(
+    thread_item.update(
         conditional_operator='or',
         forum_name__eq='Some Forum',
         subject__null=False)

docs/tutorial.rst

@@ -275,7 +275,26 @@ You can update an item with the latest data from your table:
     >>> thread_item.refresh()
 
 Updates to table items are supported too, even atomic updates. Here is an example of
-atomically updating the view count of an item:
+atomically updating the view count of an item + updating the value of the last post.
+
+.. code-block:: python
+
+    >>> thread_item.update({
+            'views': {
+                'action': 'add',
+                'value': 1,
+            },
+            'last_post_datetime': {
+                'action': 'put',
+                'value': datetime.now(),
+            },
+        })
+
+
+.. deprecated:: 2.0
+
+    :func:`update_item` is replaced with :func:`update`
+
 
 .. code-block:: python
 

examples/model.py

@@ -180,6 +180,18 @@ class Meta:
     subject__null=False)
 )
 
+# DynamoDB will atomically update the attributes `replies` (increase value by 1),
+# and `last_post_datetime` (set value to the current datetime)
+print(thread_item.update({
+    'replies': {
+        'action': 'add',
+        'value': 1,
+    },
+    'last_post_datetime': {
+        'action': 'put',
+        'value': datetime.now(),
+    },
+}))
 
 # DynamoDB will delete the item, only if the views attribute is equal to one
 print(thread_item.delete(views__eq=1))

pynamodb/constants.py

@@ -93,8 +93,11 @@
 BINARY_SET = 'BinarySet'
 MAP = 'Map'
 LIST = 'List'
+NULL = 'NULL'
+NULL_SHORT = 'NULL'
+
 SHORT_ATTR_TYPES = [STRING_SHORT, STRING_SET_SHORT, NUMBER_SHORT, NUMBER_SET_SHORT,
-                    BINARY_SHORT, BINARY_SET_SHORT, MAP_SHORT, LIST_SHORT, BOOLEAN_SHORT]
+                    BINARY_SHORT, BINARY_SET_SHORT, MAP_SHORT, LIST_SHORT, BOOLEAN_SHORT, NULL_SHORT]
 ATTR_TYPE_MAP = {
     STRING: STRING_SHORT,
     STRING_SET: STRING_SET_SHORT,
@@ -110,7 +113,8 @@
     BINARY_SET_SHORT: BINARY_SET,
     MAP: MAP_SHORT,
     LIST: LIST_SHORT,
-    BOOLEAN: BOOLEAN_SHORT
+    BOOLEAN: BOOLEAN_SHORT,
+    NULL: NULL_SHORT,
 }
 # Constants needed for creating indexes
 LOCAL_SECONDARY_INDEX = 'LocalSecondaryIndex'
@@ -162,7 +166,6 @@
 # These are the valid select values for the Scan operation
 # See: http://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Scan.html#DDB-Scan-request-Select
 NOT_NULL = 'NOT_NULL'
-NULL = 'NULL'
 CONTAINS = 'CONTAINS'
 NOT_CONTAINS = 'NOT_CONTAINS'
 ALL_ATTRIBUTES = 'ALL_ATTRIBUTES'
@@ -246,4 +249,3 @@
 AND = 'AND'
 OR = 'OR'
 CONDITIONAL_OPERATORS = [AND, OR]
-

pynamodb/models.py

@@ -6,6 +6,8 @@
 import six
 import copy
 import logging
+import warnings
+
 from six import with_metaclass
 from pynamodb.exceptions import DoesNotExist, TableDoesNotExist, TableError
 from pynamodb.throttle import NoThrottle
@@ -323,6 +325,8 @@ def update_item(self, attribute, value=None, action=None, conditional_operator=N
         :param action: The action to take if this item already exists.
             See: http://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html#DDB-UpdateItem-request-AttributeUpdate
         """
+        warnings.warn("`Model.update_item` is deprecated in favour of `Model.update` now")
+
         self._conditional_operator_check(conditional_operator)
         args, save_kwargs = self._get_save_args(null_check=False)
         attribute_cls = None
@@ -357,6 +361,52 @@ def update_item(self, attribute, value=None, action=None, conditional_operator=N
                 setattr(self, name, attr.deserialize(value.get(ATTR_TYPE_MAP[attr.attr_type])))
         return data
 
+
+    def update(self, attributes,  conditional_operator=None, **expected_values):
+        """
+        Updates an item using the UpdateItem operation.
+
+        :param attributes: A dictionary of attributes to update in the following format
+                            {
+                                attr_name: {'value': 10, 'action': 'ADD'},
+                                next_attr: {'value': True, 'action': 'PUT'},
+                            }
+        """
+        if not isinstance(attributes, dict):
+            raise TypeError("the value of `attributes` is expected to be a dictionary")
+
+        self._conditional_operator_check(conditional_operator)
+        args, save_kwargs = self._get_save_args(null_check=False)
+        kwargs = {
+            pythonic(RETURN_VALUES):  ALL_NEW,
+            pythonic(ATTR_UPDATES): {},
+            'conditional_operator': conditional_operator,
+        }
+
+        if pythonic(RANGE_KEY) in save_kwargs:
+            kwargs[pythonic(RANGE_KEY)] = save_kwargs[pythonic(RANGE_KEY)]
+
+        if expected_values:
+            kwargs['expected'] = self._build_expected_values(expected_values, UPDATE_FILTER_OPERATOR_MAP)
+
+        attrs = self._get_attributes()
+        for attr, params in attributes.items():
+            attribute_cls = attrs[attr]
+            action = params['action'] and params['action'].upper()
+            attr_values = {ACTION: action}
+            if action != DELETE:
+                attr_values[VALUE] = self._serialize_value(attribute_cls, params['value'])
+
+            kwargs[pythonic(ATTR_UPDATES)][attribute_cls.attr_name] = attr_values
+
+        data = self._get_connection().update_item(*args, **kwargs)
+        self._throttle.add_record(data.get(CONSUMED_CAPACITY))
+        for name, value in data[ATTRIBUTES].items():
+            attr = self._get_attributes().get(name)
+            if attr:
+                setattr(self, name, attr.deserialize(value.get(ATTR_TYPE_MAP[attr.attr_type])))
+        return data
+
     def save(self, conditional_operator=None, **expected_values):
         """
         Save this object to dynamodb
@@ -1189,7 +1239,7 @@ def _deserialize(self, attrs):
 
     def _serialize(self, attr_map=False, null_check=True):
         """
-        Serializes a value for use with DynamoDB
+        Serializes all model attributes for use with DynamoDB
 
         :param attr_map: If True, then attributes are returned
         :param null_check: If True, then attributes are checked for null
@@ -1198,33 +1248,48 @@ def _serialize(self, attr_map=False, null_check=True):
         attrs = {attributes: {}}
         for name, attr in self._get_attributes().aliased_attrs():
             value = getattr(self, name)
-            if value is None:
-                if attr.null:
-                    continue
-                elif null_check:
-                    raise ValueError("Attribute '{0}' cannot be None".format(attr.attr_name))
             if isinstance(value, MapAttribute):
                 if not value.validate():
                     raise ValueError("Attribute '{0}' is not correctly typed".format(attr.attr_name))
                 value = value.get_values()
-            serialized = attr.serialize(value)
-            if serialized is None:
+
+            serialized = self._serialize_value(attr, value, null_check)
+            if NULL in serialized:
                 continue
+
             if attr_map:
-                attrs[attributes][attr.attr_name] = {
-                    ATTR_TYPE_MAP[attr.attr_type]: serialized
-                }
+                attrs[attributes][attr.attr_name] = serialized
             else:
                 if attr.is_hash_key:
-                    attrs[HASH] = serialized
+                    attrs[HASH] = serialized[ATTR_TYPE_MAP[attr.attr_type]]
                 elif attr.is_range_key:
-                    attrs[RANGE] = serialized
+                    attrs[RANGE] = serialized[ATTR_TYPE_MAP[attr.attr_type]]
                 else:
-                    attrs[attributes][attr.attr_name] = {
-                        ATTR_TYPE_MAP[attr.attr_type]: serialized
-                    }
+                    attrs[attributes][attr.attr_name] = serialized
+
         return attrs
 
+    @classmethod
+    def _serialize_value(cls, attr, value, null_check=True):
+        """
+        Serializes a value for use with DynamoDB
+
+        :param attr: an instance of `Attribute` for serialization
+        :param value: a value to be serialized
+        :param null_check: If True, then attributes are checked for null
+        """
+        if value is None:
+            serialized = None
+        else:
+            serialized = attr.serialize(value)
+
+        if serialized is None:
+            if not attr.null and null_check:
+                raise ValueError("Attribute '{0}' cannot be None".format(attr.attr_name))
+            return {NULL: True}
+
+        return {ATTR_TYPE_MAP[attr.attr_type]: serialized}
+
     @classmethod
     def _serialize_keys(cls, hash_key, range_key=None):
         """

pynamodb/tests/test_model.py

@@ -189,6 +189,7 @@ class Meta:
     icons = BinarySetAttribute()
     views = NumberAttribute(null=True)
     is_active = BooleanAttribute(null=True)
+    signature = UnicodeAttribute(null=True)
 
 
 class ThrottledUserModel(Model):
@@ -810,6 +811,74 @@ def test_delete(self):
             args = req.call_args[0][1]
             deep_eq(args, params, _assert=True)
 
+    def test_update(self):
+        """
+        Model.update
+        """
+        with patch(PATCH_METHOD) as req:
+            req.return_value = SIMPLE_MODEL_TABLE_DATA
+            item = SimpleUserModel('foo', is_active=True, email='foo@example.com', signature='foo')
+
+        with patch(PATCH_METHOD) as req:
+            req.return_value = {}
+            item.save()
+
+        with patch(PATCH_METHOD) as req:
+            req.return_value = {
+                ATTRIBUTES: {
+                    "email": {
+                        "S": "foo@example.com",
+                    },
+                    "is_active": {
+                        "NULL": None,
+                    },
+                }
+            }
+            item.update({
+                'email': {'value': 'foo@example.com', 'action': 'put'},
+                'views': {'action': 'delete'},
+                'is_active': {'value': None, 'action': 'put'},
+                'signature': {'value': None, 'action': 'put'},
+            })
+
+            args = req.call_args[0][1]
+            params = {
+                'TableName': 'SimpleModel',
+                'ReturnValues': 'ALL_NEW',
+                'Key': {
+                    'user_name': {
+                        'S': 'foo'
+                    }
+                },
+                'AttributeUpdates': {
+                    'email': {
+                        'Action': 'PUT',
+                        'Value': {
+                            'S': 'foo@example.com',
+                        },
+                    },
+                    'views': {
+                        'Action': 'DELETE',
+                    },
+                    'is_active': {
+                        'Action': 'PUT',
+                        'Value': {
+                            'NULL': True,
+                        },
+                    },
+                    'signature': {
+                        'Action': 'PUT',
+                        'Value': {
+                            'NULL': True,
+                        },
+                    },
+                },
+                'ReturnConsumedCapacity': 'TOTAL'
+            }
+            deep_eq(args, params, _assert=True)
+
+            assert item.views is None
+
     def test_update_item(self):
         """
         Model.update_item