805 lines
33 KiB
Python
805 lines
33 KiB
Python
# Copyright (c) 2011 Mitch Garnaat http://garnaat.org/
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# Copyright (c) 2011 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.layer1 import Layer1
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from boto.dynamodb.table import Table
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from boto.dynamodb.schema import Schema
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from boto.dynamodb.item import Item
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from boto.dynamodb.batch import BatchList, BatchWriteList
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from boto.dynamodb.types import get_dynamodb_type, Dynamizer, \
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LossyFloatDynamizer
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class TableGenerator(object):
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"""
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This is an object that wraps up the table_generator function.
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The only real reason to have this is that we want to be able
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to accumulate and return the ConsumedCapacityUnits element that
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is part of each response.
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:ivar last_evaluated_key: A sequence representing the key(s)
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of the item last evaluated, or None if no additional
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results are available.
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:ivar remaining: The remaining quantity of results requested.
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:ivar table: The table to which the call was made.
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"""
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def __init__(self, table, callable, remaining, item_class, kwargs):
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self.table = table
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self.callable = callable
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self.remaining = -1 if remaining is None else remaining
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self.item_class = item_class
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self.kwargs = kwargs
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self._consumed_units = 0.0
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self.last_evaluated_key = None
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self._count = 0
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self._scanned_count = 0
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self._response = None
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@property
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def count(self):
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"""
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The total number of items retrieved thus far. This value changes with
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iteration and even when issuing a call with count=True, it is necessary
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to complete the iteration to assert an accurate count value.
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"""
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self.response
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return self._count
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@property
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def scanned_count(self):
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"""
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As above, but representing the total number of items scanned by
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DynamoDB, without regard to any filters.
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"""
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self.response
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return self._scanned_count
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@property
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def consumed_units(self):
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"""
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Returns a float representing the ConsumedCapacityUnits accumulated.
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"""
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self.response
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return self._consumed_units
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@property
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def response(self):
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"""
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The current response to the call from DynamoDB.
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"""
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return self.next_response() if self._response is None else self._response
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def next_response(self):
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"""
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Issue a call and return the result. You can invoke this method
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while iterating over the TableGenerator in order to skip to the
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next "page" of results.
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"""
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# preserve any existing limit in case the user alters self.remaining
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limit = self.kwargs.get('limit')
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if (self.remaining > 0 and (limit is None or limit > self.remaining)):
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self.kwargs['limit'] = self.remaining
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self._response = self.callable(**self.kwargs)
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self.kwargs['limit'] = limit
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self._consumed_units += self._response.get('ConsumedCapacityUnits', 0.0)
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self._count += self._response.get('Count', 0)
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self._scanned_count += self._response.get('ScannedCount', 0)
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# at the expense of a possibly gratuitous dynamize, ensure that
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# early generator termination won't result in bad LEK values
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if 'LastEvaluatedKey' in self._response:
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lek = self._response['LastEvaluatedKey']
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esk = self.table.layer2.dynamize_last_evaluated_key(lek)
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self.kwargs['exclusive_start_key'] = esk
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lektuple = (lek['HashKeyElement'],)
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if 'RangeKeyElement' in lek:
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lektuple += (lek['RangeKeyElement'],)
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self.last_evaluated_key = lektuple
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else:
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self.last_evaluated_key = None
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return self._response
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def __iter__(self):
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while self.remaining != 0:
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response = self.response
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for item in response.get('Items', []):
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self.remaining -= 1
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yield self.item_class(self.table, attrs=item)
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if self.remaining == 0:
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break
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if response is not self._response:
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break
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else:
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if self.last_evaluated_key is not None:
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self.next_response()
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continue
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break
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if response is not self._response:
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continue
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break
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class Layer2(object):
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def __init__(self, aws_access_key_id=None, aws_secret_access_key=None,
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is_secure=True, port=None, proxy=None, proxy_port=None,
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debug=0, security_token=None, region=None,
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validate_certs=True, dynamizer=LossyFloatDynamizer):
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self.layer1 = Layer1(aws_access_key_id, aws_secret_access_key,
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is_secure, port, proxy, proxy_port,
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debug, security_token, region,
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validate_certs=validate_certs)
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self.dynamizer = dynamizer()
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def use_decimals(self):
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"""
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Use the ``decimal.Decimal`` type for encoding/decoding numeric types.
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By default, ints/floats are used to represent numeric types
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('N', 'NS') received from DynamoDB. Using the ``Decimal``
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type is recommended to prevent loss of precision.
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"""
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# Eventually this should be made the default dynamizer.
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self.dynamizer = Dynamizer()
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def dynamize_attribute_updates(self, pending_updates):
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"""
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Convert a set of pending item updates into the structure
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required by Layer1.
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"""
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d = {}
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for attr_name in pending_updates:
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action, value = pending_updates[attr_name]
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if value is None:
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# DELETE without an attribute value
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d[attr_name] = {"Action": action}
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else:
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d[attr_name] = {"Action": action,
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"Value": self.dynamizer.encode(value)}
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return d
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def dynamize_item(self, item):
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d = {}
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for attr_name in item:
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d[attr_name] = self.dynamizer.encode(item[attr_name])
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return d
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def dynamize_range_key_condition(self, range_key_condition):
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"""
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Convert a layer2 range_key_condition parameter into the
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structure required by Layer1.
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"""
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return range_key_condition.to_dict()
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def dynamize_scan_filter(self, scan_filter):
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"""
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Convert a layer2 scan_filter parameter into the
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structure required by Layer1.
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"""
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d = None
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if scan_filter:
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d = {}
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for attr_name in scan_filter:
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condition = scan_filter[attr_name]
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d[attr_name] = condition.to_dict()
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return d
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def dynamize_expected_value(self, expected_value):
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"""
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Convert an expected_value parameter into the data structure
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required for Layer1.
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"""
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d = None
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if expected_value:
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d = {}
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for attr_name in expected_value:
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attr_value = expected_value[attr_name]
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if attr_value is True:
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attr_value = {'Exists': True}
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elif attr_value is False:
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attr_value = {'Exists': False}
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else:
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val = self.dynamizer.encode(expected_value[attr_name])
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attr_value = {'Value': val}
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d[attr_name] = attr_value
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return d
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def dynamize_last_evaluated_key(self, last_evaluated_key):
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"""
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Convert a last_evaluated_key parameter into the data structure
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required for Layer1.
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"""
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d = None
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if last_evaluated_key:
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hash_key = last_evaluated_key['HashKeyElement']
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d = {'HashKeyElement': self.dynamizer.encode(hash_key)}
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if 'RangeKeyElement' in last_evaluated_key:
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range_key = last_evaluated_key['RangeKeyElement']
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d['RangeKeyElement'] = self.dynamizer.encode(range_key)
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return d
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def build_key_from_values(self, schema, hash_key, range_key=None):
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"""
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Build a Key structure to be used for accessing items
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in Amazon DynamoDB. This method takes the supplied hash_key
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and optional range_key and validates them against the
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schema. If there is a mismatch, a TypeError is raised.
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Otherwise, a Python dict version of a Amazon DynamoDB Key
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data structure is returned.
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:type hash_key: int|float|str|unicode|Binary
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:param hash_key: The hash key of the item you are looking for.
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The type of the hash key should match the type defined in
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the schema.
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:type range_key: int|float|str|unicode|Binary
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:param range_key: The range key of the item your are looking for.
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This should be supplied only if the schema requires a
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range key. The type of the range key should match the
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type defined in the schema.
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"""
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dynamodb_key = {}
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dynamodb_value = self.dynamizer.encode(hash_key)
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if dynamodb_value.keys()[0] != schema.hash_key_type:
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msg = 'Hashkey must be of type: %s' % schema.hash_key_type
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raise TypeError(msg)
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dynamodb_key['HashKeyElement'] = dynamodb_value
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if range_key is not None:
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dynamodb_value = self.dynamizer.encode(range_key)
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if dynamodb_value.keys()[0] != schema.range_key_type:
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msg = 'RangeKey must be of type: %s' % schema.range_key_type
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raise TypeError(msg)
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dynamodb_key['RangeKeyElement'] = dynamodb_value
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return dynamodb_key
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def new_batch_list(self):
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"""
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Return a new, empty :class:`boto.dynamodb.batch.BatchList`
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object.
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"""
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return BatchList(self)
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def new_batch_write_list(self):
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"""
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Return a new, empty :class:`boto.dynamodb.batch.BatchWriteList`
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object.
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"""
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return BatchWriteList(self)
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def list_tables(self, limit=None):
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"""
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Return a list of the names of all tables associated with the
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current account and region.
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:type limit: int
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:param limit: The maximum number of tables to return.
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"""
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tables = []
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start_table = None
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while not limit or len(tables) < limit:
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this_round_limit = None
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if limit:
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this_round_limit = limit - len(tables)
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this_round_limit = min(this_round_limit, 100)
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result = self.layer1.list_tables(limit=this_round_limit, start_table=start_table)
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tables.extend(result.get('TableNames', []))
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start_table = result.get('LastEvaluatedTableName', None)
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if not start_table:
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break
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return tables
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def describe_table(self, name):
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"""
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Retrieve information about an existing table.
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:type name: str
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:param name: The name of the desired table.
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"""
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return self.layer1.describe_table(name)
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def table_from_schema(self, name, schema):
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"""
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Create a Table object from a schema.
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This method will create a Table object without
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making any API calls. If you know the name and schema
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of the table, you can use this method instead of
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``get_table``.
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Example usage::
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table = layer2.table_from_schema(
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'tablename',
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Schema.create(hash_key=('foo', 'N')))
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:type name: str
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:param name: The name of the table.
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:type schema: :class:`boto.dynamodb.schema.Schema`
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:param schema: The schema associated with the table.
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:rtype: :class:`boto.dynamodb.table.Table`
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:return: A Table object representing the table.
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"""
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return Table.create_from_schema(self, name, schema)
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def get_table(self, name):
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"""
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Retrieve the Table object for an existing table.
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:type name: str
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:param name: The name of the desired table.
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:rtype: :class:`boto.dynamodb.table.Table`
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:return: A Table object representing the table.
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"""
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response = self.layer1.describe_table(name)
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return Table(self, response)
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lookup = get_table
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def create_table(self, name, schema, read_units, write_units):
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"""
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Create a new Amazon DynamoDB table.
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:type name: str
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:param name: The name of the desired table.
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:type schema: :class:`boto.dynamodb.schema.Schema`
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:param schema: The Schema object that defines the schema used
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by this table.
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:type read_units: int
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:param read_units: The value for ReadCapacityUnits.
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:type write_units: int
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:param write_units: The value for WriteCapacityUnits.
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:rtype: :class:`boto.dynamodb.table.Table`
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:return: A Table object representing the new Amazon DynamoDB table.
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"""
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response = self.layer1.create_table(name, schema.dict,
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{'ReadCapacityUnits': read_units,
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'WriteCapacityUnits': write_units})
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return Table(self, response)
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def update_throughput(self, table, read_units, write_units):
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"""
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Update the ProvisionedThroughput for the Amazon DynamoDB Table.
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:type table: :class:`boto.dynamodb.table.Table`
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:param table: The Table object whose throughput is being updated.
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:type read_units: int
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:param read_units: The new value for ReadCapacityUnits.
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:type write_units: int
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:param write_units: The new value for WriteCapacityUnits.
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"""
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response = self.layer1.update_table(table.name,
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{'ReadCapacityUnits': read_units,
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'WriteCapacityUnits': write_units})
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table.update_from_response(response)
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def delete_table(self, table):
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"""
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Delete this table and all items in it. After calling this
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the Table objects status attribute will be set to 'DELETING'.
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:type table: :class:`boto.dynamodb.table.Table`
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:param table: The Table object that is being deleted.
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"""
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response = self.layer1.delete_table(table.name)
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table.update_from_response(response)
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def create_schema(self, hash_key_name, hash_key_proto_value,
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range_key_name=None, range_key_proto_value=None):
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"""
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Create a Schema object used when creating a Table.
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:type hash_key_name: str
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:param hash_key_name: The name of the HashKey for the schema.
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:type hash_key_proto_value: int|long|float|str|unicode|Binary
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:param hash_key_proto_value: A sample or prototype of the type
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of value you want to use for the HashKey. Alternatively,
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you can also just pass in the Python type (e.g. int, float, etc.).
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:type range_key_name: str
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:param range_key_name: The name of the RangeKey for the schema.
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This parameter is optional.
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:type range_key_proto_value: int|long|float|str|unicode|Binary
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:param range_key_proto_value: A sample or prototype of the type
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of value you want to use for the RangeKey. Alternatively,
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you can also pass in the Python type (e.g. int, float, etc.)
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This parameter is optional.
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"""
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hash_key = (hash_key_name, get_dynamodb_type(hash_key_proto_value))
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if range_key_name and range_key_proto_value is not None:
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range_key = (range_key_name,
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get_dynamodb_type(range_key_proto_value))
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else:
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range_key = None
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return Schema.create(hash_key, range_key)
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def get_item(self, table, hash_key, range_key=None,
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attributes_to_get=None, consistent_read=False,
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item_class=Item):
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"""
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Retrieve an existing item from the table.
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:type table: :class:`boto.dynamodb.table.Table`
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:param table: The Table object from which the item is retrieved.
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:type hash_key: int|long|float|str|unicode|Binary
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:param hash_key: The HashKey of the requested item. The
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type of the value must match the type defined in the
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schema for the table.
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:type range_key: int|long|float|str|unicode|Binary
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:param range_key: The optional RangeKey of the requested item.
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The type of the value must match the type defined in the
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schema for the table.
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:type attributes_to_get: list
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:param attributes_to_get: A list of attribute names.
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If supplied, only the specified attribute names will
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be returned. Otherwise, all attributes will be returned.
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:type consistent_read: bool
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:param consistent_read: If True, a consistent read
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request is issued. Otherwise, an eventually consistent
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request is issued.
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:type item_class: Class
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:param item_class: Allows you to override the class used
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to generate the items. This should be a subclass of
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:class:`boto.dynamodb.item.Item`
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"""
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key = self.build_key_from_values(table.schema, hash_key, range_key)
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response = self.layer1.get_item(table.name, key,
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attributes_to_get, consistent_read,
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object_hook=self.dynamizer.decode)
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item = item_class(table, hash_key, range_key, response['Item'])
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if 'ConsumedCapacityUnits' in response:
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item.consumed_units = response['ConsumedCapacityUnits']
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return item
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def batch_get_item(self, batch_list):
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"""
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Return a set of attributes for a multiple items in
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multiple tables using their primary keys.
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:type batch_list: :class:`boto.dynamodb.batch.BatchList`
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:param batch_list: A BatchList object which consists of a
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list of :class:`boto.dynamoddb.batch.Batch` objects.
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Each Batch object contains the information about one
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batch of objects that you wish to retrieve in this
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request.
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"""
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request_items = batch_list.to_dict()
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return self.layer1.batch_get_item(request_items,
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object_hook=self.dynamizer.decode)
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|
|
def batch_write_item(self, batch_list):
|
|
"""
|
|
Performs multiple Puts and Deletes in one batch.
|
|
|
|
:type batch_list: :class:`boto.dynamodb.batch.BatchWriteList`
|
|
:param batch_list: A BatchWriteList object which consists of a
|
|
list of :class:`boto.dynamoddb.batch.BatchWrite` objects.
|
|
Each Batch object contains the information about one
|
|
batch of objects that you wish to put or delete.
|
|
"""
|
|
request_items = batch_list.to_dict()
|
|
return self.layer1.batch_write_item(request_items,
|
|
object_hook=self.dynamizer.decode)
|
|
|
|
def put_item(self, item, expected_value=None, return_values=None):
|
|
"""
|
|
Store a new item or completely replace an existing item
|
|
in Amazon DynamoDB.
|
|
|
|
:type item: :class:`boto.dynamodb.item.Item`
|
|
:param item: The Item to write to Amazon DynamoDB.
|
|
|
|
:type expected_value: dict
|
|
:param expected_value: A dictionary of name/value pairs that you expect.
|
|
This dictionary should have name/value pairs where the name
|
|
is the name of the attribute and the value is either the value
|
|
you are expecting or False if you expect the attribute not to
|
|
exist.
|
|
|
|
:type return_values: str
|
|
:param return_values: Controls the return of attribute
|
|
name-value pairs before then were changed. Possible
|
|
values are: None or 'ALL_OLD'. If 'ALL_OLD' is
|
|
specified and the item is overwritten, the content
|
|
of the old item is returned.
|
|
"""
|
|
expected_value = self.dynamize_expected_value(expected_value)
|
|
response = self.layer1.put_item(item.table.name,
|
|
self.dynamize_item(item),
|
|
expected_value, return_values,
|
|
object_hook=self.dynamizer.decode)
|
|
if 'ConsumedCapacityUnits' in response:
|
|
item.consumed_units = response['ConsumedCapacityUnits']
|
|
return response
|
|
|
|
def update_item(self, item, expected_value=None, return_values=None):
|
|
"""
|
|
Commit pending item updates to Amazon DynamoDB.
|
|
|
|
:type item: :class:`boto.dynamodb.item.Item`
|
|
:param item: The Item to update in Amazon DynamoDB. It is expected
|
|
that you would have called the add_attribute, put_attribute
|
|
and/or delete_attribute methods on this Item prior to calling
|
|
this method. Those queued changes are what will be updated.
|
|
|
|
:type expected_value: dict
|
|
:param expected_value: A dictionary of name/value pairs that you
|
|
expect. This dictionary should have name/value pairs where the
|
|
name is the name of the attribute and the value is either the
|
|
value you are expecting or False if you expect the attribute
|
|
not to exist.
|
|
|
|
:type return_values: str
|
|
:param return_values: Controls the return of attribute name/value pairs
|
|
before they were updated. Possible values are: None, 'ALL_OLD',
|
|
'UPDATED_OLD', 'ALL_NEW' or 'UPDATED_NEW'. If 'ALL_OLD' is
|
|
specified and the item is overwritten, the content of the old item
|
|
is returned. If 'ALL_NEW' is specified, then all the attributes of
|
|
the new version of the item are returned. If 'UPDATED_NEW' is
|
|
specified, the new versions of only the updated attributes are
|
|
returned.
|
|
|
|
"""
|
|
expected_value = self.dynamize_expected_value(expected_value)
|
|
key = self.build_key_from_values(item.table.schema,
|
|
item.hash_key, item.range_key)
|
|
attr_updates = self.dynamize_attribute_updates(item._updates)
|
|
|
|
response = self.layer1.update_item(item.table.name, key,
|
|
attr_updates,
|
|
expected_value, return_values,
|
|
object_hook=self.dynamizer.decode)
|
|
item._updates.clear()
|
|
if 'ConsumedCapacityUnits' in response:
|
|
item.consumed_units = response['ConsumedCapacityUnits']
|
|
return response
|
|
|
|
def delete_item(self, item, expected_value=None, return_values=None):
|
|
"""
|
|
Delete the item from Amazon DynamoDB.
|
|
|
|
:type item: :class:`boto.dynamodb.item.Item`
|
|
:param item: The Item to delete from Amazon DynamoDB.
|
|
|
|
:type expected_value: dict
|
|
:param expected_value: A dictionary of name/value pairs that you expect.
|
|
This dictionary should have name/value pairs where the name
|
|
is the name of the attribute and the value is either the value
|
|
you are expecting or False if you expect the attribute not to
|
|
exist.
|
|
|
|
:type return_values: str
|
|
:param return_values: Controls the return of attribute
|
|
name-value pairs before then were changed. Possible
|
|
values are: None or 'ALL_OLD'. If 'ALL_OLD' is
|
|
specified and the item is overwritten, the content
|
|
of the old item is returned.
|
|
"""
|
|
expected_value = self.dynamize_expected_value(expected_value)
|
|
key = self.build_key_from_values(item.table.schema,
|
|
item.hash_key, item.range_key)
|
|
return self.layer1.delete_item(item.table.name, key,
|
|
expected=expected_value,
|
|
return_values=return_values,
|
|
object_hook=self.dynamizer.decode)
|
|
|
|
def query(self, table, hash_key, range_key_condition=None,
|
|
attributes_to_get=None, request_limit=None,
|
|
max_results=None, consistent_read=False,
|
|
scan_index_forward=True, exclusive_start_key=None,
|
|
item_class=Item, count=False):
|
|
"""
|
|
Perform a query on the table.
|
|
|
|
:type table: :class:`boto.dynamodb.table.Table`
|
|
:param table: The Table object that is being queried.
|
|
|
|
:type hash_key: int|long|float|str|unicode|Binary
|
|
:param hash_key: The HashKey of the requested item. The
|
|
type of the value must match the type defined in the
|
|
schema for the table.
|
|
|
|
:type range_key_condition: :class:`boto.dynamodb.condition.Condition`
|
|
:param range_key_condition: A Condition object.
|
|
Condition object can be one of the following types:
|
|
|
|
EQ|LE|LT|GE|GT|BEGINS_WITH|BETWEEN
|
|
|
|
The only condition which expects or will accept two
|
|
values is 'BETWEEN', otherwise a single value should
|
|
be passed to the Condition constructor.
|
|
|
|
:type attributes_to_get: list
|
|
:param attributes_to_get: A list of attribute names.
|
|
If supplied, only the specified attribute names will
|
|
be returned. Otherwise, all attributes will be returned.
|
|
|
|
:type request_limit: int
|
|
:param request_limit: The maximum number of items to retrieve
|
|
from Amazon DynamoDB on each request. You may want to set
|
|
a specific request_limit based on the provisioned throughput
|
|
of your table. The default behavior is to retrieve as many
|
|
results as possible per request.
|
|
|
|
:type max_results: int
|
|
:param max_results: The maximum number of results that will
|
|
be retrieved from Amazon DynamoDB in total. For example,
|
|
if you only wanted to see the first 100 results from the
|
|
query, regardless of how many were actually available, you
|
|
could set max_results to 100 and the generator returned
|
|
from the query method will only yeild 100 results max.
|
|
|
|
:type consistent_read: bool
|
|
:param consistent_read: If True, a consistent read
|
|
request is issued. Otherwise, an eventually consistent
|
|
request is issued.
|
|
|
|
:type scan_index_forward: bool
|
|
:param scan_index_forward: Specified forward or backward
|
|
traversal of the index. Default is forward (True).
|
|
|
|
:type count: bool
|
|
:param count: If True, Amazon DynamoDB returns a total
|
|
number of items for the Query operation, even if the
|
|
operation has no matching items for the assigned filter.
|
|
If count is True, the actual items are not returned and
|
|
the count is accessible as the ``count`` attribute of
|
|
the returned object.
|
|
|
|
:type exclusive_start_key: list or tuple
|
|
:param exclusive_start_key: Primary key of the item from
|
|
which to continue an earlier query. This would be
|
|
provided as the LastEvaluatedKey in that query.
|
|
|
|
:type item_class: Class
|
|
:param item_class: Allows you to override the class used
|
|
to generate the items. This should be a subclass of
|
|
:class:`boto.dynamodb.item.Item`
|
|
|
|
:rtype: :class:`boto.dynamodb.layer2.TableGenerator`
|
|
"""
|
|
if range_key_condition:
|
|
rkc = self.dynamize_range_key_condition(range_key_condition)
|
|
else:
|
|
rkc = None
|
|
if exclusive_start_key:
|
|
esk = self.build_key_from_values(table.schema,
|
|
*exclusive_start_key)
|
|
else:
|
|
esk = None
|
|
kwargs = {'table_name': table.name,
|
|
'hash_key_value': self.dynamizer.encode(hash_key),
|
|
'range_key_conditions': rkc,
|
|
'attributes_to_get': attributes_to_get,
|
|
'limit': request_limit,
|
|
'count': count,
|
|
'consistent_read': consistent_read,
|
|
'scan_index_forward': scan_index_forward,
|
|
'exclusive_start_key': esk,
|
|
'object_hook': self.dynamizer.decode}
|
|
return TableGenerator(table, self.layer1.query,
|
|
max_results, item_class, kwargs)
|
|
|
|
def scan(self, table, scan_filter=None,
|
|
attributes_to_get=None, request_limit=None, max_results=None,
|
|
exclusive_start_key=None, item_class=Item, count=False):
|
|
"""
|
|
Perform a scan of DynamoDB.
|
|
|
|
:type table: :class:`boto.dynamodb.table.Table`
|
|
:param table: The Table object that is being scanned.
|
|
|
|
:type scan_filter: A dict
|
|
:param scan_filter: A dictionary where the key is the
|
|
attribute name and the value is a
|
|
:class:`boto.dynamodb.condition.Condition` object.
|
|
Valid Condition objects include:
|
|
|
|
* EQ - equal (1)
|
|
* NE - not equal (1)
|
|
* LE - less than or equal (1)
|
|
* LT - less than (1)
|
|
* GE - greater than or equal (1)
|
|
* GT - greater than (1)
|
|
* NOT_NULL - attribute exists (0, use None)
|
|
* NULL - attribute does not exist (0, use None)
|
|
* CONTAINS - substring or value in list (1)
|
|
* NOT_CONTAINS - absence of substring or value in list (1)
|
|
* BEGINS_WITH - substring prefix (1)
|
|
* IN - exact match in list (N)
|
|
* BETWEEN - >= first value, <= second value (2)
|
|
|
|
:type attributes_to_get: list
|
|
:param attributes_to_get: A list of attribute names.
|
|
If supplied, only the specified attribute names will
|
|
be returned. Otherwise, all attributes will be returned.
|
|
|
|
:type request_limit: int
|
|
:param request_limit: The maximum number of items to retrieve
|
|
from Amazon DynamoDB on each request. You may want to set
|
|
a specific request_limit based on the provisioned throughput
|
|
of your table. The default behavior is to retrieve as many
|
|
results as possible per request.
|
|
|
|
:type max_results: int
|
|
:param max_results: The maximum number of results that will
|
|
be retrieved from Amazon DynamoDB in total. For example,
|
|
if you only wanted to see the first 100 results from the
|
|
query, regardless of how many were actually available, you
|
|
could set max_results to 100 and the generator returned
|
|
from the query method will only yeild 100 results max.
|
|
|
|
:type count: bool
|
|
:param count: If True, Amazon DynamoDB returns a total
|
|
number of items for the Scan operation, even if the
|
|
operation has no matching items for the assigned filter.
|
|
If count is True, the actual items are not returned and
|
|
the count is accessible as the ``count`` attribute of
|
|
the returned object.
|
|
|
|
:type exclusive_start_key: list or tuple
|
|
:param exclusive_start_key: Primary key of the item from
|
|
which to continue an earlier query. This would be
|
|
provided as the LastEvaluatedKey in that query.
|
|
|
|
:type item_class: Class
|
|
:param item_class: Allows you to override the class used
|
|
to generate the items. This should be a subclass of
|
|
:class:`boto.dynamodb.item.Item`
|
|
|
|
:rtype: :class:`boto.dynamodb.layer2.TableGenerator`
|
|
"""
|
|
if exclusive_start_key:
|
|
esk = self.build_key_from_values(table.schema,
|
|
*exclusive_start_key)
|
|
else:
|
|
esk = None
|
|
kwargs = {'table_name': table.name,
|
|
'scan_filter': self.dynamize_scan_filter(scan_filter),
|
|
'attributes_to_get': attributes_to_get,
|
|
'limit': request_limit,
|
|
'count': count,
|
|
'exclusive_start_key': esk,
|
|
'object_hook': self.dynamizer.decode}
|
|
return TableGenerator(table, self.layer1.scan,
|
|
max_results, item_class, kwargs)
|