Add model validation section to Getting Started guide

guides/code/getting_started/app/assets/javascripts/comments.js.coffee

@@ -1,3 +0,0 @@
-# Place all the behaviors and hooks related to the matching controller here.
-# All this logic will automatically be available in application.js.
-# You can use CoffeeScript in this file: http://jashkenas.github.com/coffee-script/

guides/code/getting_started/app/assets/javascripts/home.js.coffee

@@ -1,3 +0,0 @@
-# Place all the behaviors and hooks related to the matching controller here.
-# All this logic will automatically be available in application.js.
-# You can use CoffeeScript in this file: http://jashkenas.github.com/coffee-script/

guides/code/getting_started/app/assets/javascripts/posts.js.coffee

@@ -1,3 +0,0 @@
-# Place all the behaviors and hooks related to the matching controller here.
-# All this logic will automatically be available in application.js.
-# You can use CoffeeScript in this file: http://jashkenas.github.com/coffee-script/

guides/code/getting_started/app/assets/stylesheets/comments.css.scss

@@ -1,3 +0,0 @@
-// Place all the styles related to the Comments controller here.
-// They will automatically be included in application.css.
-// You can use Sass (SCSS) here: http://sass-lang.com/

guides/code/getting_started/app/assets/stylesheets/home.css.scss

@@ -1,3 +0,0 @@
-// Place all the styles related to the home controller here.
-// They will automatically be included in application.css.
-// You can use Sass (SCSS) here: http://sass-lang.com/

guides/code/getting_started/app/assets/stylesheets/posts.css.scss

@@ -1,3 +0,0 @@
-// Place all the styles related to the Posts controller here.
-// They will automatically be included in application.css.
-// You can use Sass (SCSS) here: http://sass-lang.com/

guides/code/getting_started/app/assets/stylesheets/scaffolds.css.scss

@@ -1,56 +0,0 @@
-body {
-  background-color: #fff;
-  color: #333;
-  font-family: verdana, arial, helvetica, sans-serif;
-  font-size: 13px;
-  line-height: 18px; }
-
-p, ol, ul, td {
-  font-family: verdana, arial, helvetica, sans-serif;
-  font-size: 13px;
-  line-height: 18px; }
-
-pre {
-  background-color: #eee;
-  padding: 10px;
-  font-size: 11px; }
-
-a {
-  color: #000;
-  &:visited {
-    color: #666; }
-  &:hover {
-    color: #fff;
-    background-color: #000; } }
-
-div {
-  &.field, &.actions {
-    margin-bottom: 10px; } }
-
-#notice {
-  color: green; }
-
-.field_with_errors {
-  padding: 2px;
-  background-color: red;
-  display: table; }
-
-#error_explanation {
-  width: 450px;
-  border: 2px solid red;
-  padding: 7px;
-  padding-bottom: 0;
-  margin-bottom: 20px;
-  background-color: #f0f0f0;
-  h2 {
-    text-align: left;
-    font-weight: bold;
-    padding: 5px 5px 5px 15px;
-    font-size: 12px;
-    margin: -7px;
-    margin-bottom: 0px;
-    background-color: #c00;
-    color: #fff; }
-  ul li {
-    font-size: 12px;
-    list-style: square; } }

guides/code/getting_started/app/controllers/posts_controller.rb

@@ -14,7 +14,10 @@ class PostsController < ApplicationController
   def create
     @post = Post.new(params[:post])
 
-    @post.save
-    redirect_to :action => :show, :id => @post.id
+    if @post.save
+      redirect_to :action => :show, :id => @post.id
+    else
+      render 'new'
+    end
   end
 end

guides/source/getting_started.textile

@@ -655,25 +655,11 @@ TIP: If you want to link to an action in the same controller, you don't
 need to specify the +:controller+ option, as Rails will use the current
 controller by default.
 
-h4. Working with Posts in the Browser
-
-Now you're ready to start working with posts. To do that, navigate to
-"http://localhost:3000":http://localhost:3000/ and then click the "My Blog"
-link:
-
-!images/posts_index.png(Posts Index screenshot)!
-
-This is the result of Rails rendering the +index+ view of your posts. There
-aren't currently any posts in the database, but if you click the +New Post+ link
-you can create one. After that, you'll find that you can edit posts, look at
-their details, or destroy them. All of the logic and HTML to handle this was
-built by the single +rails generate scaffold+ command.
-
 TIP: In development mode (which is what you're working in by default), Rails
 reloads your application with every browser request, so there's no need to stop
 and restart the web server.
 
-Congratulations, you're riding the rails! Now it's time to see how it all works.
+Congratulations, you're riding the rails! Now it’s time to see how it all works.
 
 h4. The Model
 
@@ -697,17 +683,99 @@ Open the +app/models/post.rb+ file and edit it:
 
 <ruby>
 class Post < ActiveRecord::Base
-  validates :name,  :presence => true
   validates :title, :presence => true,
                     :length => { :minimum => 5 }
 end
 </ruby>
 
-These changes will ensure that all posts have a name and a title, and that the
-title is at least five characters long. Rails can validate a variety of
-conditions in a model, including the presence or uniqueness of columns, their
+These changes will ensure that all posts have a title that is at least five characters long.
+Rails can validate a variety of conditions in a model, including the presence or uniqueness of columns, their
 format, and the existence of associated objects. Validations are covered in detail
-in "Active Record Validations and Callbacks":active_record_validations_callbacks.html#validations-overview
+in "Active Record Validations and
+Callbacks":active_record_validations_callbacks.html#validations-overview
+
+If you open +posts_controller+ again, you'll notice that we don't check
+the result of calling +@post.save+, but now if we don't pass a valid
+title, +save+ will return false and we need to show the form back to the
+user. To do that, modify the +create+ action to look like the following:
+
+<ruby>
+def new
+  @post = Post.new
+end
+
+def create
+  @post = Post.new(params[:post])
+
+  if @post.save
+    redirect_to :action => :show, :id => @post.id
+  else
+    render 'new'
+  end
+end
+</ruby>
+
+Notice that I've also added +@post = Post.new+ to the +new+ action. I'll
+explain why I did that in the next section.
+
+Now, if validations fail and +save+ returns false, we show the form back
+to the user. Note that we use +render+ instead of +redirect_to+. We do
+that because +render+ will pass the +@post+ variable back to the form,
+which contains the error information that we need.
+
+If you reload
+"http://localhost:3000/posts/new":http://localhost:3000/posts/new and
+try to save a post without a title, Rails will send you back to the
+form, but that's not very useful. You need to tell the user that
+something went wrong. To do that, you'll modify
++app/views/posts/index.html.erb+ to check for error messages:
+
+<erb>
+<%= form_for :post do |f| %>
+  <% if @post.errors.any? %>
+  <div id="errorExplanation">
+    <h2><%= pluralize(@post.errors.count, "error") %> prohibited
+	    this post from being saved:</h2>
+    <ul>
+    <% @post.errors.full_messages.each do |msg| %>
+      <li><%= msg %></li>
+    <% end %>
+    </ul>
+  </div>
+  <% end %>
+  <p>
+    <%= f.label :title %><br>
+    <%= f.text_field :title %>
+  </p>
+
+  <p>
+    <%= f.label :text %><br>
+    <%= f.text_area :text %>
+  </p>
+
+  <p>
+    <%= f.submit %>
+  </p>
+<% end %>
+
+<%= link_to 'Back', :action => :index %>
+</erb>
+
+A few things are going on. We check if there are any errors with
++@post.errors.any?+, and if that returns true we show the list of all
+errors with +@post.errors.full_messages+. +pluralize+ is a rails helper
+that takes a number and a string as its arguments. If the number is
+greater than one, the string will be automatically pluralized.
+
+The reason why we added +@post = Post.new+ in +posts_controller+ is that
+otherwise +@post+ would be +nil+ in our view, and calling
++@post.errors.any?+ would throw an error.
+
+TIP: Rails automatically wraps fields that contain an error with a div
+with class +field_with_errors+. You can define a css rule to make them
+standout.
+
+
 
 h4. Using the Console