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Contents
# frozen_string_literal: true
require_relative 'plugins/simple_attributes'
module Aws
module DynamoDBStreams
# A utility class that translates DynamoDBStream events from Lambda
# functions into their simple attribute equivalents.
class AttributeTranslator
# Parse a DynamoDBStream event hash from Lambda that contains 1 or more
# records. When using the SDK to retrieve DynamoDB stream records, use the
# `simple_attributes: true` client option instead.
#
# @param [Hash] event A DynamoDBStream event.
#
# @example Parse a DynamoDB stream event from Lambda
# def lambda_handler(event:, context:)
# records = Aws::DynamoDBStreams::AttributeTranslator.from_event(event)
# records.each do |record|
# puts record.dynamodb.new_image
# # => { "size" => 123, "enabled" => true, ... }
# end
# end
def self.from_event(event)
return unless event.is_a?(Hash)
# TODO: This implementation is slow and inefficient. It would be
# better to write a switch-case that has similar logic to AttributeValue
# used in the ValueTranslator. This implementation however provides
# consistency between both DynamoDB and DynamoDBStreams. The translator
# only works with shapes and structs and not a regular Ruby hash.
shape_ref = ClientApi::Shapes::ShapeRef.new(
shape: ClientApi::GetRecordsOutput
)
translator = Plugins::SimpleAttributes::ValueTranslator.new(
shape_ref, :unmarshal
)
parser = Aws::Json::Parser.new(shape_ref)
input = parser.parse(Aws::Json.dump(event))
translator.apply(input).records
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems