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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 an aggregation command specification from the view and options.
#
# @since 2.2.0
class Aggregation
extend Forwardable
# The mappings from ruby options to the aggregation options.
#
# @since 2.2.0
MAPPINGS = BSON::Document.new(
:allow_disk_use => 'allowDiskUse',
:max_time_ms => 'maxTimeMS',
# This is intentional; max_await_time_ms is an alias for maxTimeMS used on getmore
# commands for change streams.
:max_await_time_ms => 'maxTimeMS',
:explain => 'explain',
:bypass_document_validation => 'bypassDocumentValidation',
:collation => 'collation',
:hint => 'hint',
:comment => 'comment'
).freeze
def_delegators :@view, :collection, :database, :read, :write_concern
# @return [ Array<Hash> ] pipeline The pipeline.
attr_reader :pipeline
# @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.
# Aggregation.new(map, reduce, view, options)
#
# @param [ Array<Hash> ] pipeline The aggregation pipeline.
# @param [ Collection::View ] view The collection view.
# @param [ Hash ] options The map/reduce options.
#
# @since 2.2.0
def initialize(pipeline, view, options)
@pipeline = pipeline
@view = view
@options = options
end
# Get the specification to pass to the aggregation operation.
#
# @example Get the specification.
# builder.specification
#
# @return [ Hash ] The specification.
#
# @since 2.2.0
def specification
spec = {
selector: aggregation_command,
db_name: database.name,
read: read,
session: @options[:session]
}
write? ? spec.merge!(write_concern: write_concern) : spec
end
private
def write?
pipeline.any? { |operator| operator[:$out] || operator['$out'] }
end
def aggregation_command
command = BSON::Document.new(:aggregate => collection.name, :pipeline => pipeline)
command[:cursor] = cursor if cursor
command[:readConcern] = collection.read_concern if collection.read_concern
command.merge!(Options::Mapper.transform_documents(options, MAPPINGS))
command
end
def cursor
if options[:use_cursor] == true || options[:use_cursor].nil?
batch_size_doc
end
end
def batch_size_doc
(value = options[:batch_size] || view.batch_size) ? { :batchSize => value } : {}
end
end
end
end
end
end
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