adding two ActiveRecord::Relation objects [duplicate]

Answer 1

You can add two ActiveRecord::Relation with Arel Constraints

constraints_1 = Model.matching_one.arel.constraints
constraints_2 = Model.matching_two.arel.constraints

Model.where(constraints_1.and(constraints_2)).class => ActiveRecord::Relation

You can use or operator too

Model.where(constraints_1.or(constraints_2)).class => ActiveRecord::Relation

Real example

constraints_1 = User.where(id: 1..5).arel.constraints
constraints_2 = User.where('id != 2').arel.constraints

User.where(constraints_1.and(constraints_2))

You can watch excellent screen cast about that http://railscasts.com/episodes/355-hacking-with-arel