class RefreshAssignedSamplesCounters < ActiveRecord::Migration[4.2] def up # Reset the counters for assigned samples Sample.find_each do |sample| sample.update(nr_of_modules_assigned_to: sample.my_modules.count) end MyModule.find_each do |my_module| my_module.update(nr_of_assigned_samples: my_module.samples.count) end end end