How do to access an ActiveRecord relation ship using a string name of the relationship?

Question

I have an active record class that looks like

class User < ApplicationRecord
  has_many :audiobooks
  has_many :ebooks
  has_many :physicalbooks
end

I want to get/set the relations using the names. How can I do that?

A probable example of the operation I want to perform:

books =  [ :audiobooks, :ebooks, physicalbooks] 
books.each do |b|
  user[b].build(...)
end

How can I do this in ActiveRecord.

Answer 1

You can use send method, like so:

user.send(b)