Select on DropDownList click

Hello
I have a table with cities Cities associated to a table Regions that holds Region information, so there are specific cities for each specific Region
It’s a One to One association

I want to have an editor screen where I have a dropdownlist with the Regions and when I select one…, the second DropDownList with cities shows only the cities associated to that selected Region on the first dropdownlist.

Any ideas on how to achieve this?

Many thanks!

https://demo.jmix.io/sampler/#main/0/sample?id=cascading-dropdowns