Truncate part of a value of a string field in Kibana?

[Kulasangar_Gowrisang (Kulasangar Gowrisangar)]

I'm having a field called userid (analyzed and the datatype is text) and all it's value pretend to be as follows:

sometext@something.super
newtext@something.super

So what I need is, to trim the above value so that I can only get the text in front of @something.super.

I tried writing a painless script in order to check whether the value contains the @something.super, if so then assign the value to an empty string but still no luck.

Is trimming possible for a string field in Kibana? Or

Is it possible to trim the value in elasticsearch itself if I'm to update the existing field?

Any help could be appreciated.

[spalger (Spencer Alger)]

You could probably use a custom analyzer with a pattern tokenizer to accomplish what you are looking for:

custom analyzer: https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-custom-analyzer.html
pattern tokenizer: https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-pattern-tokenizer.html