punch.rb

class Punch < ActiveRecord::Base
   attr_accessible :clock_in, :clock_out
   belongs_to :user
end

punches_controller

class PunchesController < ApplicationController
  before_filter :authenticate_user!
  
  def clock_in
    @punch = current_user.punches.new clock_in: Time.zone.now
    @punch.save
  end
  
  def clock_out
    @punch = current_user.punches.last
    @punch.clock_out = Time.zone.now
    @punch.save

    respond_to do |format|
        format.html { redirect_to punches_path }
    end
  end
end

schema

# encoding: UTF-8
# This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# Note that this schema.rb definition is the authoritative source for your
# database schema. If you need to create the application database on another
# system, you should be using db:schema:load, not running all the migrations
# from scratch. The latter is a flawed and unsustainable approach (the more migrations
# you'll amass, the slower it'll run and the greater likelihood for issues).
#
# It's strongly recommended to check this file into your version control system.

ActiveRecord::Schema.define(:version => 20120904142435) do

  create_table "models", :force => true do |t|
    t.string   "email",                  :default => "", :null => false
    t.string   "encrypted_password",     :default => "", :null => false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          :default => 0
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.datetime "created_at",                             :null => false
    t.datetime "updated_at",                             :null => false
  end

  add_index "models", ["email"], :name => "index_models_on_email", :unique => true
  add_index "models", ["reset_password_token"], :name => "index_models_on_reset_password_token", :unique => true

  create_table "punches", :force => true do |t|
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
    t.datetime "clock_in"
    t.datetime "clock_out"
    t.integer  "user_id"
  end

  create_table "users", :force => true do |t|
    t.string   "email",                  :default => "", :null => false
    t.string   "encrypted_password",     :default => "", :null => false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          :default => 0
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.datetime "created_at",                             :null => false
    t.datetime "updated_at",                             :null => false
    t.string   "username"
  end

  add_index "users", ["email"], :name => "index_users_on_email", :unique => true
  add_index "users", ["reset_password_token"], :name => "index_users_on_reset_password_token", :unique => true

end

user.rb

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :token_authenticatable, :confirmable,
  # :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable, :timeoutable
  
  has_many :punches

  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :password, :password_confirmation, :remember_me
  # attr_accessible :title, :body
end