Use build with has_one and belongs_to association

Suppose we have association between two models as has_one and belongs_to. We want to create the child record with parent record using build method than need to follow below easy steps.

eg. Class User < ActiveRecord::Base

        has_one :profile
      end

      

     Class Profile < ActiveRecord::Base

        belongs_to :user

     end

   

When we are creating the user than required to create associated profile by using below methods:

@user.build_profile or
@user.profile.build

It create associated profile record along with user.