Logstash aggregation overwrite

[fuzes]

I don't know why aggregation is overwritten by last one
following is my logstash code

filter {
  aggregate {
    task_id => "%{code}"
      code => "
        map['code'] = event.get('code')
        map[event.get('language')] ||= {
            'name' => event.get('name')
            ...
        }
      push_previous_map_as_event => true
      push_map_as_event_on_timeout => true
      timeout_task_id_field => "task_id"
      timeout => 3000
  }
  mutate {
    copy => { "code" => "[@metadata][_id]" }
    remove_field => ["code", "@version", "unix_ts_in_secs"]
  }
}

and following is mysql result...

mysql rows =
["code" "language", "name"] = [[10345, "jp", "test1"], [10345, "th", "test2]]

i want to

jp:  {
 name: "test1"
}
th: {
  name: "test2"
}

but result have always just last language data

th: {
   name: "test2"
}

i don't know why aggregation doesn't work well

[Badger]

@fuzes

        map[event.get('language')] ||= {
            'name' => event.get('name')
            ...
        }

That only sets map["10345"] if it is nil. I think what you want is

    map[event.get('language')] ||= []
    map[event.get('language')] << { 'name' => event.get('name') }