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# Copyright 2011-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.
module AWS
class DynamoDB
# Represents a DynamoDB item. An item is identified by simple or
# complex primary key (according to the table schema) and consists
# of a collection of attributes. Attributes are name/value pairs
# where the value may be a string, number, string set, or number
# set.
#
# Getting an item by hash key value:
#
# item = table.items['hash-key-value']
#
# Getting an item from a table with both hash and range keys:
#
# item = table.items['hash-key','range-key']
#
class Item < Core::Resource
extend Types
include Keys
include Expectations
# @return [Table] The table in which the item is stored.
attr_reader :table
# @return [String, Numeric] The hash key value of the item.
attr_reader :hash_value
# @return [String, Numeric, nil] The range key value of the
# item, or `nil` if the table has a simple primary key.
attr_reader :range_value
# @api private
def initialize(table, *args)
opts = args.pop if args.last.kind_of?(Hash)
(@hash_value, @range_value) = args
@table = table
super(table, opts)
end
# Deletes the item.
#
# @param [Hash] options Options for deleting the item.
#
# @option options [Hash] :if Designates a conditional delete.
# The operation will fail unless the item exists and has the
# attributes in the value for this option. For example:
#
# # throws DynamoDB::Errors::ConditionalCheckFailedException
# # unless the item has "color" set to "red"
# item.delete(:if => { :color => "red" })
#
# @option options [String, Symbol, Array] :unless_exists A name
# or collection of attribute names; if the item has a value
# for any of these attributes, this method will raise
# `DynamoDB::Errors::ConditionalCheckFailedException`. For
# example:
#
# item.delete(:unless_exists => "version")
def delete(options = {})
client_opts = item_key_options(self)
expected = expect_conditions(options)
client_opts[:expected] = expected unless expected.empty?
client_opts[:return_values] = options[:return].to_s.upcase if
options[:return]
resp = client.delete_item(client_opts)
values_from_response_hash(resp.data["Attributes"]) if
options[:return] and resp.data["Attributes"]
end
# @return [Boolean] True if the item exists.
def exists?(options = {})
client_opts = item_key_options(self, options)
client_opts[:attributes_to_get] = [table.hash_key.name]
resp = client.get_item(client_opts)
resp.data.key?("Item")
end
# @return [AttributeCollection] An object representing the
# attributes of the item.
def attributes
AttributeCollection.new(self)
end
# @api private
def self.new_from(op, response_object, table, *args)
config = args.last.is_a?(Hash) ? args.last : AWS.config
table.assert_schema!
hash_value =
value_from_response(response_object[table.hash_key.name])
range_value =
value_from_response(response_object[table.range_key.name]) if
table.range_key
raise "missing hash key value in put_item response" unless hash_value
raise "missing range key value in put_item response" unless
range_value || !table.range_key
super(op, response_object,
table, hash_value, range_value, *args)
end
protected
def resource_identifiers
[[:table_name, table.name],
[:hash_value, hash_value],
[:range_value, range_value]]
end
end
end
end
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