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# frozen_string_literal: true
# rubocop:todo all
# Copyright (C) 2015-2020 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',
bypass_document_validation: 'bypassDocumentValidation',
explain: 'explain',
collation: 'collation',
comment: 'comment',
hint: 'hint',
let: 'let',
# This is intentional; max_await_time_ms is an alias for maxTimeMS
# used on getMore commands for change streams.
max_await_time_ms: 'maxTimeMS',
max_time_ms: 'maxTimeMS',
).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.
#
# @param [ Array<Hash> ] pipeline The aggregation pipeline.
# @param [ Collection::View ] view The collection view.
# @param [ Hash ] options The map/reduce and read preference 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: @options[:read_preference] || view.read_preference,
session: @options[:session],
collation: @options[:collation],
}
if write?
spec.update(write_concern: write_concern)
end
spec
end
private
def write?
pipeline.any? do |operator|
operator[:$out] || operator['$out'] ||
operator[:$merge] || operator['$merge']
end
end
def aggregation_command
command = BSON::Document.new
# aggregate must be the first key in the command document
if view.is_a?(Collection::View)
command[:aggregate] = collection.name
elsif view.is_a?(Database::View)
command[:aggregate] = 1
else
raise ArgumentError, "Unknown view class: #{view}"
end
command[:pipeline] = pipeline
if read_concern = view.read_concern
command[:readConcern] = Options::Mapper.transform_values_to_strings(
read_concern)
end
command[:cursor] = batch_size_doc
command.merge!(Options::Mapper.transform_documents(options, MAPPINGS))
command
end
def batch_size_doc
value = options[:batch_size] || view.batch_size
if value == 0 && write?
{}
elsif value
{ :batchSize => value }
else
{}
end
end
end
end
end
end
end
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