Kibana scripted field url formatting with a string

I love new kibana 4 feature that allows me to create URL based on variables. It's brilliant thank for that.
It works just fine when I use number value doc['variable'].value or like this _source.variable

But when I reference string value I get errors.
Is there any other way apart from duplicating the variable in elasticsearch and formatting it directly as new_variable
to achieve something like that ?

Thanks & regards

The default language for Kibana scripted fields is Lucene expressions, which can only work with integers at this time.

You can instead use Groovy scripts, which can operate on strings, but take care to do so in a secure manner (dynamic scripts are insecure, so you must use static scripts). More on that in this thread: Calling groovy script from Kibana