203 lines
8.1 KiB
Python
203 lines
8.1 KiB
Python
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# Copyright (c) 2012 Mitch Garnaat http://garnaat.org/
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# Copyright (c) 2012 Amazon.com, Inc. or its affiliates. All Rights Reserved
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#
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# Permission is hereby granted, free of charge, to any person obtaining a
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# copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish, dis-
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# tribute, sublicense, and/or sell copies of the Software, and to permit
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# persons to whom the Software is furnished to do so, subject to the fol-
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# lowing conditions:
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#
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# The above copyright notice and this permission notice shall be included
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# in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
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# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
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# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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# IN THE SOFTWARE.
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#
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from boto.dynamodb.exceptions import DynamoDBItemError
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class Item(dict):
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"""
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An item in Amazon DynamoDB.
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:ivar hash_key: The HashKey of this item.
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:ivar range_key: The RangeKey of this item or None if no RangeKey
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is defined.
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:ivar hash_key_name: The name of the HashKey associated with this item.
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:ivar range_key_name: The name of the RangeKey associated with this item.
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:ivar table: The Table this item belongs to.
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"""
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def __init__(self, table, hash_key=None, range_key=None, attrs=None):
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self.table = table
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self._updates = None
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self._hash_key_name = self.table.schema.hash_key_name
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self._range_key_name = self.table.schema.range_key_name
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if attrs is None:
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attrs = {}
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if hash_key is None:
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hash_key = attrs.get(self._hash_key_name, None)
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self[self._hash_key_name] = hash_key
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if self._range_key_name:
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if range_key is None:
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range_key = attrs.get(self._range_key_name, None)
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self[self._range_key_name] = range_key
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self._updates = {}
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for key, value in attrs.items():
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if key != self._hash_key_name and key != self._range_key_name:
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self[key] = value
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self.consumed_units = 0
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@property
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def hash_key(self):
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return self[self._hash_key_name]
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@property
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def range_key(self):
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return self.get(self._range_key_name)
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@property
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def hash_key_name(self):
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return self._hash_key_name
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@property
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def range_key_name(self):
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return self._range_key_name
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def add_attribute(self, attr_name, attr_value):
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"""
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Queue the addition of an attribute to an item in DynamoDB.
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This will eventually result in an UpdateItem request being issued
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with an update action of ADD when the save method is called.
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:type attr_name: str
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:param attr_name: Name of the attribute you want to alter.
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:type attr_value: int|long|float|set
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:param attr_value: Value which is to be added to the attribute.
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"""
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self._updates[attr_name] = ("ADD", attr_value)
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def delete_attribute(self, attr_name, attr_value=None):
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"""
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Queue the deletion of an attribute from an item in DynamoDB.
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This call will result in a UpdateItem request being issued
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with update action of DELETE when the save method is called.
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:type attr_name: str
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:param attr_name: Name of the attribute you want to alter.
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:type attr_value: set
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:param attr_value: A set of values to be removed from the attribute.
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This parameter is optional. If None, the whole attribute is
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removed from the item.
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"""
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self._updates[attr_name] = ("DELETE", attr_value)
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def put_attribute(self, attr_name, attr_value):
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"""
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Queue the putting of an attribute to an item in DynamoDB.
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This call will result in an UpdateItem request being issued
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with the update action of PUT when the save method is called.
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:type attr_name: str
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:param attr_name: Name of the attribute you want to alter.
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:type attr_value: int|long|float|str|set
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:param attr_value: New value of the attribute.
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"""
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self._updates[attr_name] = ("PUT", attr_value)
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def save(self, expected_value=None, return_values=None):
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"""
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Commits pending updates to Amazon DynamoDB.
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:type expected_value: dict
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:param expected_value: A dictionary of name/value pairs that
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you expect. This dictionary should have name/value pairs
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where the name is the name of the attribute and the value is
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either the value you are expecting or False if you expect
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the attribute not to exist.
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:type return_values: str
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:param return_values: Controls the return of attribute name/value pairs
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before they were updated. Possible values are: None, 'ALL_OLD',
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'UPDATED_OLD', 'ALL_NEW' or 'UPDATED_NEW'. If 'ALL_OLD' is
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specified and the item is overwritten, the content of the old item
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is returned. If 'ALL_NEW' is specified, then all the attributes of
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the new version of the item are returned. If 'UPDATED_NEW' is
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specified, the new versions of only the updated attributes are
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returned.
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"""
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return self.table.layer2.update_item(self, expected_value,
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return_values)
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def delete(self, expected_value=None, return_values=None):
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"""
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Delete the item from DynamoDB.
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:type expected_value: dict
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:param expected_value: A dictionary of name/value pairs that
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you expect. This dictionary should have name/value pairs
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where the name is the name of the attribute and the value
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is either the value you are expecting or False if you expect
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the attribute not to exist.
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:type return_values: str
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:param return_values: Controls the return of attribute
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name-value pairs before then were changed. Possible
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values are: None or 'ALL_OLD'. If 'ALL_OLD' is
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specified and the item is overwritten, the content
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of the old item is returned.
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"""
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return self.table.layer2.delete_item(self, expected_value,
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return_values)
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def put(self, expected_value=None, return_values=None):
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"""
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Store a new item or completely replace an existing item
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in Amazon DynamoDB.
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:type expected_value: dict
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:param expected_value: A dictionary of name/value pairs that
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you expect. This dictionary should have name/value pairs
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where the name is the name of the attribute and the value
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is either the value you are expecting or False if you expect
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the attribute not to exist.
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:type return_values: str
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:param return_values: Controls the return of attribute
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name-value pairs before then were changed. Possible
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values are: None or 'ALL_OLD'. If 'ALL_OLD' is
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specified and the item is overwritten, the content
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of the old item is returned.
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"""
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return self.table.layer2.put_item(self, expected_value, return_values)
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def __setitem__(self, key, value):
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"""Overrwrite the setter to instead update the _updates
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method so this can act like a normal dict"""
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if self._updates is not None:
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self.put_attribute(key, value)
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dict.__setitem__(self, key, value)
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def __delitem__(self, key):
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"""Remove this key from the items"""
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if self._updates is not None:
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self.delete_attribute(key)
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dict.__delitem__(self, key)
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# Allow this item to still be pickled
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def __getstate__(self):
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return self.__dict__
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def __setstate__(self, d):
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self.__dict__.update(d)
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