class VProduct
  include Mongoid::Document
  include Mongoid::Timestamps
  include Tire::Model::Search
  include Tire::Model::Callbacks

  field :vid, :type=>Integer   
  field :name                   # name -        Bezeichnung

  index :vid, unique: true

when I set vid to a String, the doc is valid and i can save it. (and the string gets saved instead of an integer)

shouldnt vid only accept Integers in this case?

In my case i use the gem tire for elasticsearch. and it won't index documents which don't have an integer set for vid.