models def self.by_letter(letter) where("lastname LIKE ?", "#{letter}%").order(:lastname) end controller def index if params[:letter] @contacts = Contact.by_letter(params[:letter]) else @contacts = Contact.order('lastname, firstname') end …

app/models/hoge.rb def name [firstname, lastname].join(' ') end #もしくは def name firstname + lastname end

app/models/contact.rb class Contact < ActiveRecord::Base has_many phones phoneモデルで同じcontact_idは持てないようにuniqunessな制約をつけると実現できる。 app/models/phone.rb class Phone < ActiveRecord::Base belongs_to :contact validates :p…