Manipulating Nested Fields

Elastic Stack Logstash
1

Hi,
Given a field [field][sub-field], how can I move the value from "sub-field" to field? That is, convert this from an object to a string?

I've tried:

mutate {
    covert => { "field" => "string" }
}

and:

 mutate {
    copy => { [field][subfield] => "new_field" }
}

Neither has worked.

Thx
D

2

If you want convert:

mutate {
    covert => { "[field][sub-field]" => "string" }
}

Copy:

 mutate {
    copy => { "[field][subfield]" => "new_field" }
}