Change "null" to null value

[lelwar]

Hello,
I have an application that sends through the rest API a Json to logstash and this is filtered and outputted to an Elasticsearch cluster. The json is nested, so I have flattened it using the "split" codec in logstash like the following:

mutate {
	  add_field => { "primary_nested" => "%{[primary][nested]}" }
}

It works well, but when the nested field is empty (null) the value given to a field will be the string: "%{[primary][nested]}" because it finds no value. Is there a way to filter it so that if the value comes as "null" it leaves it empty so that Elasticsearch can receive it as null?

regards,

Israel

[Badger]

Wrap it in this?

if [primary][nested] {
...
}