Get the Value of an array, in the output config

Hi,

I have the corresponding config file :

input {
  elasticsearch {
    hosts => "localhost"
    index => "articles"
    add_field => { "[@metadata][kafka_topics]" => ["test1", "test2"] }
  }
}
output {
  stdout { codec => rubydebug{
      metadata => true
    } }
  kafka {
    topic_ids => "%{[@metadata][kafka_topics]}"
  }
}

I have changed the output plugin for kafka so now it is supporting arrays .
topic_ids => ["test1","test2"] works smoothly.
but when I try to access the value of the variable it is treated as a string no matter what I try.

Yes, I don't think there's a way around this. Logstash's configuration language is primitive.

yes,
Is there a way to split the string by ',' in the output config ?
else, can I do something to change how the "%{}" works?

I ended up splitting the array inside the kafka's output plugin.
thanks for the help.