I don't really understand this behavior

mongo_visitor.rb

relation = base_relation.restrict do |r|
  r.name.eq "Cologne"
end.sort_by do |r|
  [ r.name, r.country ]
end

mongo_visitor = Veritas::Adapter::Mongo::Visitor.new relation

p mongo_visitor.query
#=> {:name=>"Cologne"}

@moonglum btw, you can also write the restrict part like base_relation.restrict(:name => 'Cologne'), this is a short cut for the common case where you just want to do an equality match of one or more attributes.