Add some validations to User and errors to form

app/models/user.rb

@@ -1,13 +1,13 @@
 class User < ActiveRecord::Base
   has_many :orders
-  before_save :init
 
+  validates :name, presence: true
+  validates :last_name, presence: true
+  validates :nickname, presence: true, uniqueness: true
 
-
-  def init
-    self.balance ||= 0
+  def full_name
+    "#{name} #{last_name}"
   end
 
-
   has_secure_password
 end

app/views/application/_errors.html.erb

@@ -0,0 +1,5 @@
+<ul>
+  <% model.errors.full_messages.each do |e| %>
+    <%= content_tag(:li, e) %>
+  <% end %>
+</ul>

app/views/users/new.html.erb

@@ -3,6 +3,8 @@
 <div class="row">
   <div class="col-md-6 col-md-offset-3">
     <%= form_for(@user) do |f| %>
+      <%= render partial: 'errors', locals: { model: @user } %>
+
       <%= f.label :nickname %>
       <%= f.text_field :nickname %>
 

db/migrate/20141125102501_add_default_value_balance_to_users.rb

@@ -0,0 +1,5 @@
+class AddDefaultValueBalanceToUsers < ActiveRecord::Migration
+  def change
+    change_column :users, :balance, :integer, default: 0
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20141124091707) do
+ActiveRecord::Schema.define(version: 20141125102501) do
 
   create_table "orders", force: true do |t|
     t.integer  "user_id"
@@ -36,7 +36,7 @@ ActiveRecord::Schema.define(version: 20141124091707) do
   create_table "users", force: true do |t|
     t.string   "name"
     t.string   "last_name"
-    t.integer  "balance"
+    t.integer  "balance",         default: 0
     t.string   "nickname"
     t.string   "password_digest"
     t.datetime "created_at"