Pattern matching sangat powerful terutama untuk handling input dari external, bisa type checking + variable binding dalam satu step.
Awalnya cuma ada di bahasa functional seperti Erlang, Elixir, Scala, dsb., sekarang ada di Ruby sejak 3.0.
https://docs.ruby-lang.org/en/3.0/syntax/pattern_matching_rdoc.html
| def parse_event(sqs_message) | |
| JSON.parse(sqs_message.body) => Hash => parsed_sqs_body | |
| parsed_sqs_body["Message"] => String => raw_sns_message | |
| JSON.parse(raw_sns_message) => Hash => parsed_sns_message | |
| parsed_sns_message["AutoScalingGroupName"] => String => asg | |
| parsed_sns_message["EC2InstanceId"] => String => instance_id | |
| parsed_sns_message["Event"] => String => event | |
| Environment.where(autoscaling_group: asg).pick(:environment_name) => String => environment_name | |
| [ event, { environment_name: environment_name, instance_id: instance_id } ] | |
| rescue NoMatchingPatternError | |
| nil | |
| rescue JSON::ParserError => e | |
| Rails.logger.error "Failed to parse message: #{e.message}" | |
| nil | |
| end |
| def parse_event(sqs_message) | |
| message_body = JSON.parse(sqs_message.body) | |
| return nil unless message_body.is_a?(Hash) | |
| return nil unless message_body["Message"].is_a?(String) | |
| sns_message = JSON.parse(message_body["Message"]) | |
| return nil unless sns_message.is_a?(Hash) | |
| environment_name = Environment.where(autoscaling_group: sns_message["AutoScalingGroupName"]) | |
| .pick(:environment_name) | |
| return nil unless environment_name | |
| [ sns_message["Event"], { environment_name: environment_name, instance_id: sns_message["EC2InstanceId"] } ] | |
| rescue JSON::ParserError => e | |
| Rails.logger.error "Failed to parse message: #{e.message}" | |
| nil | |
| end |