Grouping on field with multiple values

Webix JS
#1

I have a field with multiple values. I want to group on that field. Currently the grouping will show a group row for every combination of mixed values for that field as in this example: https://snippet.webix.com/06i3u1qe
As you can see for the group “1999” only the movies that have a SINGLE value of 1999 are being listed.
Is there some way to group on the individual values as a separate group?
So in the example above, can we have the group “1999” list any movie that was in 1999 (single value or multiple values)?

#2

Hello @peaceofmind ,

A custom grouping functor can be declared as a function of any complexity:

// short declaration without data mapping or other options
$group : function( obj ){ return obj.year }

// detailed configuration
$group : {
   by:function(obj){ return obj.year  },
   map:{  votes:["votes", "sum"]  }
}

Please note that the functor handles each date item separately.
Here’s an example of a custom grouping: https://snippet.webix.com/bnfaw7iv
Any condition is applicable, so here’s also grouping by the 1st item of multiple values: https://snippet.webix.com/w96ipgfo