Trashable concern via http://stackoverflow.com/a/13299736/73779

20120625030355_add_deleted_at_to_user.rb

# db/migrate/20120625030355_add_deleted_at_to_user.rb

class AddDeletedAtToUser < ActiveRecord::Migration
  def change
    add_column :users, :deleted_at, :datetime
  end
end

trashable.rb

# app/models/concerns/trashable.rb

module Trashable
  extend ActiveSupport::Concern

  included do
    default_scope { where(deleted_at: nil) }
  end

  module ClassMethods
    def trashed
      self.unscoped.where(self.arel_table[:deleted_at].not_eq(nil))
    end
  end

  def destroy
    run_callbacks :destroy do
      update_column :deleted_at, Time.now
    end
  end

  def recover
    # update_column not appropriate here as it uses the default scope
    update_attribute :deleted_at, nil
  end
end

user.rb

# app/models/user.rb

class User < ActiveRecord::Base
  include Trashable
end