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# Copyright (C) 2015-2017 MongoDB, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License 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 Mongo
class Collection
class View
module Builder
# Builds a map/reduce specification from the view and options.
#
# @since 2.2.0
class MapReduce
extend Forwardable
# The mappings from ruby options to the map/reduce options.
#
# @since 2.2.0
MAPPINGS = BSON::Document.new(
finalize: 'finalize',
js_mode: 'jsMode',
out: 'out',
scope: 'scope',
verbose: 'verbose',
bypass_document_validation: 'bypassDocumentValidation',
collation: 'collation'
).freeze
def_delegators :@view, :collection, :database, :filter, :read, :write_concern
# @return [ String ] map The map function.
attr_reader :map
# @return [ String ] reduce The reduce function.
attr_reader :reduce
# @return [ Collection::View ] view The collection view.
attr_reader :view
# @return [ Hash ] options The map/reduce specific options.
attr_reader :options
# Initialize the builder.
#
# @example Initialize the builder.
# MapReduce.new(map, reduce, view, options)
#
# @param [ String ] map The map function.
# @param [ String ] reduce The reduce function.
# @param [ Collection::View ] view The collection view.
# @param [ Hash ] options The map/reduce options.
#
# @since 2.2.0
def initialize(map, reduce, view, options)
@map = map
@reduce = reduce
@view = view
@options = options
end
# Get the specification for issuing a find command on the map/reduce
# results.
#
# @example Get the command specification.
# builder.command_specification
#
# @return [ Hash ] The specification.
#
# @since 2.2.0
def command_specification
{
selector: find_command,
db_name: query_database,
read: read,
session: options[:session]
}
end
# Get the specification for the document query after a map/reduce.
#
# @example Get the query specification.
# builder.query_specification
#
# @return [ Hash ] The specification.
#
# @since 2.2.0
def query_specification
{ selector: {}, options: {}, db_name: query_database, coll_name: query_collection }
end
# Get the specification to pass to the map/reduce operation.
#
# @example Get the specification.
# builder.specification
#
# @return [ Hash ] The specification.
#
# @since 2.2.0
def specification
spec = {
selector: map_reduce_command,
db_name: database.name,
read: read,
session: options[:session]
}
write?(spec) ? spec.merge!(write_concern: write_concern) : spec
end
private
OUT_ACTIONS = [ :replace, :merge, :reduce ].freeze
def write?(spec)
if out = spec[:selector][:out]
out.is_a?(String) ||
(out.respond_to?(:keys) && out.keys.first.to_s.downcase != View::MapReduce::INLINE)
end
end
def find_command
BSON::Document.new('find' => query_collection, 'filter' => {})
end
def map_reduce_command
command = BSON::Document.new(
:mapreduce => collection.name,
:map => map,
:reduce => reduce,
:query => filter,
:out => { inline: 1 }
)
command[:readConcern] = collection.read_concern if collection.read_concern
command.merge!(view_options)
command.merge!(Options::Mapper.transform_documents(options, MAPPINGS))
command
end
def query_database
options[:out].respond_to?(:keys) && options[:out][:db] ? options[:out][:db] : database.name
end
def query_collection
if options[:out].respond_to?(:keys)
options[:out][OUT_ACTIONS.find { |action| options[:out][action] }]
end || options[:out]
end
def view_options
@view_options ||= (opts = view.options.dup
opts.delete(:session)
opts)
end
end
end
end
end
end
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