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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
module Record
class HashModel
# The primary interface for finding records with {AWS::Record::HashModel}.
#
# ## Getting a Scope Object
#
# You should normally never need to construct a Scope object directly.
# Scope objects are returned from the AWS::Record::HashModel finder
# methods # (e.g. `shard` and `limit`).
#
# books = Book.limit(100)
# books.class #=> AWS::Record::HashModel::Scope
#
# Scopes are also returned from methods defined with the `scope` method.
#
# class Book < AWS::Record::HashModel
# scope :sampling, limit(10)
# end
#
# Book.sampling #=> returns a scope that limits to 10
#
# ## Chaining Scopes
#
# Scope objects represent a request, but do not actualy make a request
# until required. This allows you to chain requests
#
# # no request made by the following 2 statements
# books = Book.shard('books-1') # what table to search
# books = books.limit(10) # how many records to fetch
#
# books.each do |book|
# # yields up to 10 books from the table 'books-1'
# end
#
# The following methods returns a scope that can be chained.
#
# * {#shard}
# * {#limit}
#
# ## Terminating Scopes
#
# To terminate a scope you can enumerate it or call #first.
#
# # terminate a scope by enumerating
# Book.limit(10).each {|book| ... }
#
# # terminate a scope by getting the first record
# Book.shard('books-1').first
#
class Scope < Record::Scope
private
def _each_object &block
items = _item_collection
items.select(:limit => @options[:limit]).each do |item_data|
obj = base_class.new(:shard => _shard)
obj.send(:hydrate, item_data.attributes['id'], item_data.attributes)
yield(obj)
end
end
private
def _merge_scope scope
merged = self
scope.instance_variable_get('@options').each_pair do |opt_name,opt_value|
unless [nil, []].include?(opt_value)
merged = merged.send(opt_name, *opt_value)
end
end
merged
end
private
def _handle_options options
scope = self
options.each_pair do |method, args|
scope = scope.send(method, *args)
end
scope
end
private
def _item_collection
base_class.dynamo_db_table(_shard).items
end
end
end
end
end
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