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diff --git a/guides/source/getting_started.textile b/guides/source/getting_started.textile index 59b12b49e5..44f3b978db 100644 --- a/guides/source/getting_started.textile +++ b/guides/source/getting_started.textile @@ -10,7 +10,7 @@ you should be familiar with: endprologue. -WARNING. This Guide is based on Rails 3.1. Some of the code shown here will not +WARNING. This Guide is based on Rails 3.2. Some of the code shown here will not work in earlier versions of Rails. WARNING: The Edge version of this guide is currently being re-worked. Please excuse us while we re-arrange the place. @@ -27,8 +27,8 @@ prerequisites installed: TIP: Note that Ruby 1.8.7 p248 and p249 have marshaling bugs that crash Rails 3.0. Ruby Enterprise Edition have these fixed since release 1.8.7-2010.02 though. On the 1.9 front, Ruby 1.9.1 is not usable because it outright segfaults -on Rails 3.0, so if you want to use Rails 3 with 1.9.x jump on 1.9.2 for smooth -sailing. +on Rails 3.0, so if you want to use Rails 3 with 1.9.x jump on 1.9.2 or +1.9.3 for smooth sailing. * The "RubyGems":http://rubyforge.org/frs/?group_id=126 packaging system ** If you want to learn more about RubyGems, please read the "RubyGems User Guide":http://docs.rubygems.org/read/book/1 @@ -45,10 +45,6 @@ internet for learning Ruby, including: h3. What is Rails? -TIP: This section goes into the background and philosophy of the Rails framework -in detail. You can safely skip this section and come back to it at a later time. -Section 3 starts you on the path to creating your first Rails application. - Rails is a web application development framework written in the Ruby language. It is designed to make programming web applications easier by making assumptions about what every developer needs to get started. It allows you to write less @@ -73,9 +69,11 @@ h3. Creating a New Rails Project The best way to use this guide is to follow each step as it happens, no code or step needed to make this example application has been left out, so you can -literally follow along step by step. You can get the complete code "here":https://github.com/lifo/docrails/tree/master/guides/code/getting_started. +literally follow along step by step. You can get the complete code +"here":https://github.com/lifo/docrails/tree/master/guides/code/getting_started. -By following along with this guide, you'll create a Rails project called <tt>blog</tt>, a +By following along with this guide, you'll create a Rails project called ++blog+, a (very) simple weblog. Before you can start building the application, you need to make sure that you have Rails itself installed. @@ -97,7 +95,7 @@ To verify that you have everything installed correctly, you should be able to ru $ rails --version </shell> -If it says something like "Rails 3.2.2" you are ready to continue. +If it says something like "Rails 3.2.3" you are ready to continue. h4. Creating the Blog Application @@ -111,7 +109,8 @@ $ rails new blog This will create a Rails application called Blog in a directory called blog. -TIP: You can see all of the switches that the Rails application builder accepts by running <tt>rails new -h</tt>. +TIP: You can see all of the command line options that the Rails +application builder accepts by running +rails new -h+. After you create the blog application, switch to its folder to continue work directly in that application: @@ -119,7 +118,10 @@ After you create the blog application, switch to its folder to continue work dir $ cd blog </shell> -The +rails new blog+ command we ran above created a folder in your working directory called <tt>blog</tt>. The <tt>blog</tt> directory has a number of auto-generated files and folders that make up the structure of a Rails application. Most of the work in this tutorial will happen in the <tt>app/</tt> folder, but here's a basic rundown on the function of each of the files and folders that Rails created by default: +The +rails new blog+ command we ran above created a folder in your +working directory called +blog+. The +blog+ directory has a number of +auto-generated files and folders that make up the structure of a Rails +application. Most of the work in this tutorial will happen in the +app/+ folder, but here's a basic rundown on the function of each of the files and folders that Rails created by default: |_.File/Folder|_.Purpose| |app/|Contains the controllers, models, views, helpers, mailers and assets for your application. You'll focus on this folder for the remainder of this guide.| @@ -140,7 +142,7 @@ The +rails new blog+ command we ran above created a folder in your working direc h3. Hello, Rails! -One of the traditional places to start with a new language is by getting some text up on screen quickly. To do this, you need to get your Rails application server running. +To begin with, let's get some text up on screen quickly. To do this, you need to get your Rails application server running. h4. Starting up the Web Server @@ -152,7 +154,7 @@ $ rails server TIP: Compiling CoffeeScript to JavaScript requires a JavaScript runtime and the absence of a runtime will give you an +execjs+ error. Usually Mac OS X and Windows come with a JavaScript runtime installed. Rails adds the +therubyracer+ gem to Gemfile in a commented line for new apps and you can uncomment if you need it. +therubyrhino+ is the recommended runtime for JRuby users and is added by default to Gemfile in apps generated under JRuby. You can investigate about all the supported runtimes at "ExecJS":https://github.com/sstephenson/execjs#readme. -This will fire up an instance of a webserver built into Ruby called WEBrick by default. To see your application in action, open a browser window and navigate to "http://localhost:3000":http://localhost:3000. You should see the Rails default information page: +This will fire up WEBrick, a webserver built into Ruby by default. To see your application in action, open a browser window and navigate to "http://localhost:3000":http://localhost:3000. You should see the Rails default information page: !images/rails_welcome.png(Welcome Aboard screenshot)! @@ -164,7 +166,7 @@ h4. Say "Hello", Rails To get Rails saying "Hello", you need to create at minimum a _controller_ and a _view_. -A controller's purpose is to receive specific requests for the application. What controller receives what request is determined by the _routing_. There is very often more than one route to each controller, and different routes can be served by different _actions_. Each action's purpose is to collect information to provide it to a view. +A controller's purpose is to receive specific requests for the application. _Routing_ decides which controller receives which requests. Often, there is more than one route to each controller, and different routes can be served by different _actions_. Each action's purpose is to collect information to provide it to a view. A view's purpose is to display this information in a human readable format. An important distinction to make is that it is the _controller_, not the view, where information is collected. The view should just display that information. By default, view templates are written in a language called ERB (Embedded Ruby) which is converted by the request cycle in Rails before being sent to the user. @@ -225,7 +227,6 @@ h4. Laying down the ground work The first thing that you are going to need to create a new post within the application is a place to do that. A great place for that would be at +/posts/new+. If you attempt to navigate to that now -- by visiting "http://localhost:3000/posts/new":http://localhost:3000/posts/new -- Rails will give you a routing error: - !images/getting_started/routing_error_no_route_matches.png(A routing error, no route matches /posts/new)! This is because there is nowhere inside the routes for the application -- defined inside +config/routes.rb+ -- that defines this route. By default, Rails has no routes configured at all, and so you must define your routes as you need them. @@ -240,7 +241,7 @@ This route is a super-simple route: it defines a new route that only responds to With the route defined, requests can now be made to +/posts/new+ in the application. Navigate to "http://localhost:3000/posts/new":http://localhost:3000/posts/new and you'll see another routing error: -!images/getting_started/routing_error_no_controller.png(Another routing error, uninitialized constant PostsController) +!images/getting_started/routing_error_no_controller.png(Another routing error, uninitialized constant PostsController)! This error is happening because this route need a controller to be defined. The route is attempting to find that controller so it can serve the request, but with the controller undefined, it just can't do that. The solution to this particular problem is simple: you need to create a controller called +PostsController+. You can do this by running this command: @@ -259,7 +260,7 @@ A controller is simply a class that is defined to inherit from +ApplicationContr If you refresh "http://localhost:3000/posts/new":http://localhost:3000/posts/new now, you'll get a new error: -!images/getting_started/unknown_action_new_for_posts.png(Unknown action new for PostsController!) +!images/getting_started/unknown_action_new_for_posts.png(Unknown action new for PostsController!)! This error indicates that Rails cannot find the +new+ action inside the +PostsController+ that you just generated. This is because when controllers are generated in Rails they are empty by default, unless you tell it you wanted actions during the generation process. @@ -272,7 +273,7 @@ end With the +new+ method defined in +PostsController+, if you refresh "http://localhost:3000/posts/new":http://localhost:3000/posts/new you'll see another error: -!images/getting_started/template_is_missing_posts_new.png(Template is missing for posts/new) +!images/getting_started/template_is_missing_posts_new.png(Template is missing for posts/new)! You're getting this error now because Rails expects plain actions like this one to have views associated with them to display their information. With no view available, Rails errors out. @@ -302,7 +303,9 @@ When you refresh "http://localhost:3000/posts/new":http://localhost:3000/posts/n h4. The first form -To create a form within this template, you will use a _form builder_. The primary form builder for Rails is provided by a helper method called +form_for+. To use this method, write this code into +app/views/posts/new.html.erb+: +To create a form within this template, you will use a <em>form +builder</em>. The primary form builder for Rails is provided by a helper +method called +form_for+. To use this method, add this code into +app/views/posts/new.html.erb+: <erb> <%= form_for :post do |f| %> @@ -346,7 +349,7 @@ By using the +post+ method rather than the +get+ method, Rails will define a rou With the form and the route for it defined now, you will be able to fill in the form and then click the submit button to begin the process of creating a new post, so go ahead and do that. When you submit the form, you should see a familiar error: -!images/getting_started/unknown_action_create_for_posts(Unknown action create for PostsController)! +!images/getting_started/unknown_action_create_for_posts.png(Unknown action create for PostsController)! You will now need to create the +create+ action within the +PostsController+ for this to work. @@ -385,25 +388,43 @@ If you re-submit the form one more time you'll now no longer get the missing tem This action is now displaying the parameters for the post that are coming in from the form. However, this isn't really all that helpful. Yes, you can see the parameters but nothing in particular is being done with them. +h4. Creating the Post model + +Models in Rails use a singular name, and their corresponding database tables use +a plural name. Rails provides a generator for creating models, which +most Rails developers tend to use when creating new models. +To create the new model, run this command in your terminal: + +<shell> +$ rails generate model Post title:string text:text +</shell> + +With that command we told Rails that we want a +Post+ model, which in +turn should have a title attribute of type string, and a text attribute +of type text. Rails in turn responded by creating a bunch of files. For +now, we're only interested in +app/models/post.rb+ and ++db/migrate/20120419084633_create_posts.rb+. The latter is responsible +for creating the database structure, which is what we'll look at next. + h4. Running a Migration -One of the products of the +rails generate scaffold+ command is a _database -migration_. Migrations are Ruby classes that are designed to make it simple to +As we've just seen, +rails generate model+ created a _database +migration_ file inside the +db/migrate+ directory. +Migrations are Ruby classes that are designed to make it simple to create and modify database tables. Rails uses rake commands to run migrations, and it's possible to undo a migration after it's been applied to your database. Migration filenames include a timestamp to ensure that they're processed in the order that they were created. -If you look in the +db/migrate/20100207214725_create_posts.rb+ file (remember, +If you look in the +db/migrate/20120419084633_create_posts.rb+ file (remember, yours will have a slightly different name), here's what you'll find: <ruby> class CreatePosts < ActiveRecord::Migration def change create_table :posts do |t| - t.string :name t.string :title - t.text :content + t.text :text t.timestamps end @@ -415,7 +436,7 @@ The above migration creates a method named +change+ which will be called when yo run this migration. The action defined in this method is also reversible, which means Rails knows how to reverse the change made by this migration, in case you want to reverse it later. When you run this migration it will create a -+posts+ table with two string columns and a text column. It also creates two ++posts+ table with one string column and a text column. It also creates two timestamp fields to allow Rails to track post creation and update times. More information about Rails migrations can be found in the "Rails Database Migrations":migrations.html guide. @@ -440,43 +461,193 @@ NOTE. Because you're working in the development environment by default, this command will apply to the database defined in the +development+ section of your +config/database.yml+ file. If you would like to execute migrations in another environment, for instance in production, you must explicitly pass it when -invoking the command: <tt>rake db:migrate RAILS_ENV=production</tt>. +invoking the command: +rake db:migrate RAILS_ENV=production+. + +h4. Saving data in the controller + +Back in +posts_controller+, we need to change the +create+ action +to use the new +Post+ model to save data in the database. Open that file +and change the +create+ action to look like the following: + +<ruby> +def create + @post = Post.new(params[:post]) + + @post.save + redirect_to :action => :show, :id => @post.id +end +</ruby> + +Here's what's going on: every Rails model can be initialized with its +respective attributes, which are automatically mapped to its +database columns. In the first line we do just that (remember that ++params[:post]+ contains the attributes we're interested in). Then, ++@post.save+ is responsible for saving the model in the database. +Finally, on the last line we redirect the user to the +show+ action, +wich we have not defined yet. + +TIP: As we'll see later, +@post.save+ returns a boolean indicating +wherever the model was saved or not, and you can (and usually do) take +different actions depending on the result of calling +@post.save+. + +h4. Showing posts + +Before trying to create a new post, let's add the +show+ action, which +will be responsible for showing our posts. Open +config/routes.rb+ +and add the following route: + +<ruby> +get "posts/:id" => "posts#show" +</ruby> + +The special syntax +:id+ tells rails that this route expects an +:id+ +parameter, which in our case will be the id of the post. Note that this +time we had to specify the actual mapping, +posts#show+ because +otherwise Rails would not know which action to render. + +As we did before, we need to add the +show+ action in the ++posts_controller+ and its respective view. + +<ruby> +def show + @post = Post.find(params[:id]) +end +</ruby> + +A couple of things to note. We use +Post.find+ to find the post we're +interested in. We also use an instance variable (prefixed by +@+) to +hold a reference to the post object. We do this because Rails will pass all instance +variables to the view. + +Now, create a new file +app/view/posts/show.html.erb+ with the following +content: + +<erb> +<p> + <strong>Title:</strong> + <%= @post.title %> +</p> + +<p> + <strong>Text:</strong> + <%= @post.text %> +</p> +</erb> + +Finally, if you now go to +"http://localhost:3000/posts/new":http://localhost:3000/posts/new you'll +be able to create a post. Try it! -h4. Adding a Link +!images/getting_started/show_action_for_posts.png(Show action for posts)! -To hook the posts up to the home page you've already created, you can add a link -to the home page. Open +app/views/welcome/index.html.erb+ and modify it as follows: +h4. Listing all posts + +We still need a way to list all our posts, so let's do that. As usual, +we'll need a route, a controller action, and a view: + +<ruby> +# Add to config/routes.rb +get "posts" => "posts#index" + +# Add to app/controllers/posts_controller.rb +def index + @posts = Post.all +end +</ruby> + ++app/view/posts/index.html.erb+: + +<erb> +<h1>Listing posts</h1> + +<table> + <tr> + <th>Title</th> + <th>Text</th> + </tr> + +<% @posts.each do |post| %> + <tr> + <td><%= post.title %></td> + <td><%= post.text %></td> + </tr> +<% end %> +</table> +</erb> + +h4. Adding links + +You can now create, show, and list posts. Now let's add some links to +navigate through pages. + +Open +app/views/welcome/index.html.erb+ and modify it as follows: <ruby> <h1>Hello, Rails!</h1> -<%= link_to "My Blog", posts_path %> +<%= link_to "My Blog", :controller => "posts" %> </ruby> The +link_to+ method is one of Rails' built-in view helpers. It creates a hyperlink based on text to display and where to go - in this case, to the path for posts. -h4. Working with Posts in the Browser +Let's add links to the other views as well. + +<erb> +# app/views/posts/index.html.erb + +<h1>Listing posts</h1> + +<%= link_to 'New post', :action => :new %> + +<table> + <tr> + <th>Title</th> + <th>Text</th> + <th></th> + </tr> + +<% @posts.each do |post| %> + <tr> + <td><%= post.title %></td> + <td><%= post.text %></td> + <td><%= link_to 'Show', :action => :show, :id => post.id %></td> + </tr> +<% end %> +</table> + +# app/views/posts/new.html.erb + +<%= form_for :post do |f| %> + ... +<% end %> + +<%= link_to 'Back', :action => :index %> -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: +# app/views/posts/show.html.erb -!images/posts_index.png(Posts Index screenshot)! +<p> + <strong>Title:</strong> + <%= @post.title %> +</p> -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. +<p> + <strong>Text:</strong> + <%= @post.text %> +</p> + +<%= link_to 'Back', :action => :index %> +</erb> + +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. 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. +and restart the web server when a change is made. -h4. The Model +h4. Adding Some Validation The model file, +app/models/post.rb+ is about as simple as it can get: @@ -491,208 +662,279 @@ your Rails models for free, including basic database CRUD (Create, Read, Update, Destroy) operations, data validation, as well as sophisticated search support and the ability to relate multiple models to one another. -h4. Adding Some Validation - Rails includes methods to help you validate the data that you send to models. 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 -h4. Using the Console +If you open +posts_controller+ again, you'll notice that we don't check +the result of calling +@post.save+. We need to change its behavior to +show the form back to the user if any error occur: -To see your validations in action, you can use the console. The console is a -command-line tool that lets you execute Ruby code in the context of your -application: +<ruby> +def new + @post = Post.new +end -<shell> -$ rails console -</shell> +def create + @post = Post.new(params[:post]) -TIP: The default console will make changes to your database. You can instead -open a console that will roll back any changes you make by using <tt>rails console ---sandbox</tt>. + if @post.save + redirect_to :action => :show, :id => @post.id + else + render 'new' + end +end +</ruby> -After the console loads, you can use it to work with your application's models: +Notice that I've also added +@post = Post.new+ to the +new+ action. I'll +explain why I did that in the next section, for now add that to your +controller as well. -<shell> ->> p = Post.new(:content => "A new post") -=> #<Post id: nil, name: nil, title: nil, - content: "A new post", created_at: nil, - updated_at: nil> ->> p.save -=> false ->> p.errors.full_messages -=> ["Name can't be blank", "Title can't be blank", "Title is too short (minimum is 5 characters)"] -</shell> +Also notice that we use +render+ instead of +redirect_to+ when +save+ +returns false. We can use +render+ so that the +@post+ object is passed +back to the view. + +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, :url => { :action => :create } 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 in that case we show a 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. + +Now you'll get a nice error message when saving a post without title: -This code shows creating a new +Post+ instance, attempting to save it and -getting +false+ for a return value (indicating that the save failed), and -inspecting the +errors+ of the post. +!images/getting_started/form_with_errors.png(Form With Errors)! -When you're finished, type +exit+ and hit +return+ to exit the console. +h4. Updating Posts -TIP: Unlike the development web server, the console does not automatically load -your code afresh for each line. If you make changes to your models (in your editor) -while the console is open, type +reload!+ at the console prompt to load them. +We've covered the "CR" part of CRUD. Now let's focus on the "U" part, +updating posts. -h4. Listing All Posts +The first step we'll take is adding a +edit+ action to ++posts_controller+. -Let's dive into the Rails code a little deeper to see how the application is -showing us the list of Posts. Open the file -+app/controllers/posts_controller.rb+ and look at the -+index+ action: +Start by adding a route to +config/routes.rb+: <ruby> -def index - @posts = Post.all +get "posts/:id/edit" => "posts#edit" +</ruby> + +And then add the controller action: + +<ruby> +def edit + @post = Post.find(params[:id]) +end +</ruby> + +The view will contain a form similar to the one we used when creating +new posts. Create a file called +app/views/posts/edit.html.erb+ and make +it look as follows: + +<erb> +<h1>Editing post</h1> + +<%= form_for :post, :url => { :action => :update, :id => @post.id }, +:method => :put 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> + +This time we point the form to the +update+ action (not defined yet). +The +:method => :put+ option tells Rails that we want this form to be +submitted via +put+, which is the http method you're expected to use to +*update* resources according to the REST protocol. + +TIP: By default forms built with the +form_for_ helper are sent via +POST+. + +Moving on, we need to add the +update+ action. The file ++config/routes.rb+ will need just one more line: - respond_to do |format| - format.html # index.html.erb - format.json { render :json => @posts } +<ruby> +put "posts/:id" => "posts#update" +</ruby> + +And the +update+ action in +posts_controller+ itself should not look too complicated by now: + +<ruby> +def update + @post = Post.find(params[:id]) + + if @post.update_attributes(params[:post]) + redirect_to :action => :show, :id => @post.id + else + render 'edit' end end </ruby> -+Post.all+ returns all of the posts currently in the database as an array -of +Post+ records that we store in an instance variable called +@posts+. +The new method +update_attributes+ is used when you want to update a record +that already exists, and it accepts an hash containing the attributes +that you want to update. As before, if there was an error updating the +post we want to show the form back to the user. -TIP: For more information on finding records with Active Record, see "Active -Record Query Interface":active_record_querying.html. +TIP: you don't need to pass all attributes to +update_attributes+. For +example, if you'd call +@post.update_attributes(:title => 'A new title')+ +Rails would only update the +title+ attribute, leaving all other +attributes untouched. -The +respond_to+ block handles both HTML and JSON calls to this action. If you -browse to "http://localhost:3000/posts.json":http://localhost:3000/posts.json, -you'll see a JSON containing all of the posts. The HTML format looks for a view -in +app/views/posts/+ with a name that corresponds to the action name. Rails -makes all of the instance variables from the action available to the view. -Here's +app/views/posts/index.html.erb+: +Finally, we want to show a link to the +edit+ action in the +index+ and ++show+ views: <erb> -<h1>Listing posts</h1> +# app/view/posts/index.html.erb <table> <tr> - <th>Name</th> <th>Title</th> - <th>Content</th> - <th></th> + <th>Text</th> <th></th> <th></th> </tr> <% @posts.each do |post| %> <tr> - <td><%= post.name %></td> <td><%= post.title %></td> - <td><%= post.content %></td> - <td><%= link_to 'Show', post %></td> - <td><%= link_to 'Edit', edit_post_path(post) %></td> - <td><%= link_to 'Destroy', post, :confirm => 'Are you sure?', - :method => :delete %></td> + <td><%= post.text %></td> + <td><%= link_to 'Show', :action => :show, :id => post.id %></td> + <td><%= link_to 'Edit', :action => :edit, :id => post.id %></td> </tr> <% end %> </table> -<br /> - -<%= link_to 'New post', new_post_path %> -</erb> +# app/view/posts/show.html.erb -This view iterates over the contents of the +@posts+ array to display content -and links. A few things to note in the view: +... -* +link_to+ builds a hyperlink to a particular destination -* +edit_post_path+ and +new_post_path+ are helpers that Rails provides as part of RESTful routing. You'll see a variety of these helpers for the different actions that the controller includes. +<%= link_to 'Back', :action => :index %> +| <%= link_to 'Edit', :action => :edit, :id => @post.id %> +</erb> -NOTE. In previous versions of Rails, you had to use +<%=h post.name %>+ so -that any HTML would be escaped before being inserted into the page. In Rails -3 and above, this is now the default. To get unescaped HTML, you now use <tt><%= raw post.name %></tt>. +And here's how our app looks so far: -TIP: For more details on the rendering process, see "Layouts and Rendering in -Rails":layouts_and_rendering.html. +!images/getting_started/index_action_with_edit_link.png(Index action +with edit link)! -h4. Customizing the Layout +h4. Using partials to clean up duplication in views -The view is only part of the story of how HTML is displayed in your web browser. -Rails also has the concept of +layouts+, which are containers for views. When -Rails renders a view to the browser, it does so by putting the view's HTML into -a layout's HTML. In previous versions of Rails, the +rails generate scaffold+ -command would automatically create a controller specific layout, like -+app/views/layouts/posts.html.erb+, for the posts controller. However this has -been changed in Rails 3. An application specific +layout+ is used for all the -controllers and can be found in +app/views/layouts/application.html.erb+. Open -this layout in your editor and modify the +body+ tag to include the style directive -below: ++partials+ are what Rails uses to remove duplication in views. Here's a +simple example: <erb> -<!DOCTYPE html> -<html> -<head> - <title>Blog</title> - <%= stylesheet_link_tag "application" %> - <%= javascript_include_tag "application" %> - <%= csrf_meta_tags %> -</head> -<body style="background-color: #EEEEEE;"> - -<%= yield %> - -</body> -</html> -</erb> - -Now when you refresh the +/posts+ page, you'll see a gray background to the -page. This same gray background will be used throughout all the views. +# app/views/user/show.html.erb -h4. Creating New Posts +<h1><%= @user.name %></h1> -Creating a new post involves two actions. The first is the +new+ action, which -instantiates an empty +Post+ object: +<%= render 'user_details' %> -<ruby> -def new - @post = Post.new - - respond_to do |format| - format.html # new.html.erb - format.json { render :json => @post } - end -end -</ruby> +# app/views/user/_user_details.html.erb -The +new.html.erb+ view displays this empty Post to the user: +<%= @user.location %> -<erb> -<h1>New post</h1> +<%= @user.about_me %> +</erb> -<%= render 'form' %> +The +show+ view will automatically include the content of the ++_user_details+ view. Note that partials are prefixed by an underscore, +as to not be confused with regular views. However, you don't include the +underscore when including them with the +helper+ method. -<%= link_to 'Back', posts_path %> -</erb> +TIP: You can read more about partials in the "Layouts and Rendering in +Rails":layouts_and_rendering.html guide. -The +<%= render 'form' %>+ line is our first introduction to _partials_ in -Rails. A partial is a snippet of HTML and Ruby code that can be reused in -multiple locations. In this case, the form used to make a new post is basically -identical to the form used to edit a post, both having text fields for the name and -title, a text area for the content, and a button to create the new post or to update -the existing one. +Our +edit+ action looks very similar to the +new+ action, in fact they +both share the same code for displaying the form. Lets clean them up by +using a +_form+ partial. -If you take a look at +views/posts/_form.html.erb+ file, you will see the -following: +Create a new file +app/views/posts/_form.html.erb+ with the following +content: <erb> -<%= form_for(@post) do |f| %> +<%= form_for @post do |f| %> <% if @post.errors.any? %> <div id="errorExplanation"> <h2><%= pluralize(@post.errors.count, "error") %> prohibited @@ -704,230 +946,218 @@ following: </ul> </div> <% end %> - - <div class="field"> - <%= f.label :name %><br /> - <%= f.text_field :name %> - </div> - <div class="field"> - <%= f.label :title %><br /> + <p> + <%= f.label :title %><br> <%= f.text_field :title %> - </div> - <div class="field"> - <%= f.label :content %><br /> - <%= f.text_area :content %> - </div> - <div class="actions"> + </p> + + <p> + <%= f.label :text %><br> + <%= f.text_area :text %> + </p> + + <p> <%= f.submit %> - </div> + </p> <% end %> </erb> -This partial receives all the instance variables defined in the calling view -file. In this case, the controller assigned the new +Post+ object to +@post+, -which will thus be available in both the view and the partial as +@post+. +Everything except for the +form_for+ declaration remained the same. I'll +explain later how +form_for+ can figure out the right +action+ and ++method+ attributes when building the form, for now let's update the ++new+ and +edit+ views: -For more information on partials, refer to the "Layouts and Rendering in -Rails":layouts_and_rendering.html#using-partials guide. +<erb> +# app/views/posts/new.html.erb -The +form_for+ block is used to create an HTML form. Within this block, you have -access to methods to build various controls on the form. For example, -+f.text_field :name+ tells Rails to create a text input on the form and to hook -it up to the +name+ attribute of the instance being displayed. You can only use -these methods with attributes of the model that the form is based on (in this -case +name+, +title+, and +content+). Rails uses +form_for+ in preference to -having you write raw HTML because the code is more succinct, and because it -explicitly ties the form to a particular model instance. +<h1>New post</h1> -The +form_for+ block is also smart enough to work out if you are doing a _New -Post_ or an _Edit Post_ action, and will set the form +action+ tags and submit -button names appropriately in the HTML output. +<%= render 'form' %> -TIP: If you need to create an HTML form that displays arbitrary fields, not tied -to a model, you should use the +form_tag+ method, which provides shortcuts for -building forms that are not necessarily tied to a model instance. +<%= link_to 'Back', :action => :index %> -When the user clicks the +Create Post+ button on this form, the browser will -send information back to the +create+ action of the controller (Rails knows to -call the +create+ action because the form is sent with an HTTP POST request; -that's one of the conventions that were mentioned earlier): -<ruby> -def create - @post = Post.new(params[:post]) +# app/views/posts/edit.html.erb - respond_to do |format| - if @post.save - format.html { redirect_to(@post, - :notice => 'Post was successfully created.') } - format.json { render :json => @post, - :status => :created, :location => @post } - else - format.html { render :action => "new" } - format.json { render :json => @post.errors, - :status => :unprocessable_entity } - end - end -end -</ruby> +<h1>Edit post</h1> -The +create+ action instantiates a new Post object from the data supplied by the -user on the form, which Rails makes available in the +params+ hash. After -successfully saving the new post, +create+ returns the appropriate format that -the user has requested (HTML in our case). It then redirects the user to the -resulting post +show+ action and sets a notice to the user that the Post was -successfully created. - -If the post was not successfully saved, due to a validation error, then the -controller returns the user back to the +new+ action with any error messages so -that the user has the chance to fix the error and try again. - -The "Post was successfully created." message is stored in the Rails -+flash+ hash (usually just called _the flash_), so that messages can be carried -over to another action, providing the user with useful information on the status -of their request. In the case of +create+, the user never actually sees any page -rendered during the post creation process, because it immediately redirects to -the new +Post+ as soon as Rails saves the record. The Flash carries over a message to -the next action, so that when the user is redirected back to the +show+ action, -they are presented with a message saying "Post was successfully created." - -h4. Showing an Individual Post - -When you click the +show+ link for a post on the index page, it will bring you -to a URL like +http://localhost:3000/posts/1+. Rails interprets this as a call -to the +show+ action for the resource, and passes in +1+ as the +:id+ parameter. -Here's the +show+ action: +<%= render 'form' %> -<ruby> -def show - @post = Post.find(params[:id]) +<%= link_to 'Back', :action => :index %> +</erb> - respond_to do |format| - format.html # show.html.erb - format.json { render :json => @post } - end -end -</ruby> +Point your browser to +"http://localhost:3000/posts/new":http://localhost:3000/posts/new and +try creating a new post. Everything still works. Now try editing the +post and you'll receive the following error: + +!images/getting_started/undefined_method_post_path.png(Undefined method +post_path)! + +To understand this error, you need to understand how +form_for+ works. +When you pass an object to +form_for+ and you don't specify a +:url+ +option, Rails will try to guess the +action+ and +method+ options by +checking if the passed object is a new record or not. Rails follows the +REST convention, so to create a new +Post+ object it will look for a +route named +posts_path+, and to update a +Post+ object it will look for +a route named +post_path+ and pass the current object. Similarly, rails +knows that it should create new objects via POST and update them via +PUT. + +If you run +rake routes+ from the console you'll see that we already +have a +posts_path+ route, which was created automatically by Rails. +However, we don't have a +post_path+ yet, which is the reason why we +received an error before. -The +show+ action uses +Post.find+ to search for a single record in the database -by its id value. After finding the record, Rails displays it by using -+app/views/posts/show.html.erb+: +<shell> +# rake routes + + posts GET /posts(.:format) posts#index + posts_new GET /posts/new(.:format) posts#new +posts_create POST /posts/create(.:format) posts#create + GET /posts/:id(.:format) posts#show + GET /posts/:id/edit(.:format) posts#edit + PUT /posts/:id(.:format) posts#update + root / welcome#index +</shell> -<erb> -<p id="notice"><%= notice %></p> +To fix this, open +config/routes.rb+ and modify the +get "posts/:id"+ +line like this: -<p> - <b>Name:</b> - <%= @post.name %> -</p> +<ruby> +get "posts/:id" => "posts#show", :as => :post +</ruby> -<p> - <b>Title:</b> - <%= @post.title %> -</p> +Now you'll be able to update posts again. -<p> - <b>Content:</b> - <%= @post.content %> -</p> +h4. Deleting Posts +We're now ready to cover the "D" part of CRUD, deleting posts from the +database. Following the REST convention, we're going to add a route for +deleting posts: -<%= link_to 'Edit', edit_post_path(@post) %> | -<%= link_to 'Back', posts_path %> -</erb> +<ruby> +# config/routes.rb -h4. Editing Posts +delete "posts/:id" => "posts#destroy" +</ruby> -Like creating a new post, editing a post is a two-part process. The first step -is a request to +edit_post_path(@post)+ with a particular post. This calls the -+edit+ action in the controller: +We use the +delete+ method for destroying resources, which is mapped to +the +destroy+ action, which is provided below: <ruby> -def edit +# app/controllers/posts_controller.rb + +def destroy @post = Post.find(params[:id]) + @post.destroy + + redirect_to :action => :index end </ruby> -After finding the requested post, Rails uses the +edit.html.erb+ view to display -it: +You can call +destroy+ on Active Record objects when you want to delete +them from the dabase. Note that we don't need to add a view for this +action since we're redirecting to the +index+ action. -<erb> -<h1>Editing post</h1> +Finally, add a 'destroy' link to your +index+ action to wrap everything +together. -<%= render 'form' %> +<erb> +<table> + <tr> + <th>Title</th> + <th>Text</th> + <th></th> + <th></th> + <th></th> + </tr> -<%= link_to 'Show', @post %> | -<%= link_to 'Back', posts_path %> +<% @posts.each do |post| %> + <tr> + <td><%= post.title %></td> + <td><%= post.text %></td> + <td><%= link_to 'Show', :action => :show, :id => post.id %></td> + <td><%= link_to 'Edit', :action => :edit, :id => post.id %></td> + <td><%= link_to 'Destroy', { :action => :destroy, :id => post.id }, :method => :delete, :confirm => 'Are you sure?' %></td> + </tr> +<% end %> +</table> </erb> -Again, as with the +new+ action, the +edit+ action is using the +form+ partial. -This time, however, the form will do a PUT action to the +PostsController+ and the -submit button will display "Update Post". +Here we're using +link_to+ in a different way. We wrap the ++:action+ and +:id+ attributes in a hash so that we can pass other +arguments to +link_to+. The +:method+ and +:confirm+ +options are used as html5 attributes so that when the click is linked, +Rails will first show a confirm dialog to the user, and then submit the +link with method +delete+. This is done via javascript automatically. -Submitting the form created by this view will invoke the +update+ action within -the controller: +!images/getting_started/confirm_dialog.png(Confirm Dialog)! -<ruby> -def update - @post = Post.find(params[:id]) +Congratulations, you can now create, show, list, update and destroy +posts. In the next section will see how Rails can aid us when creating +REST applications, and how we can refactor our Blog app to take +advantage of it. - respond_to do |format| - if @post.update_attributes(params[:post]) - format.html { redirect_to(@post, - :notice => 'Post was successfully updated.') } - format.json { head :no_content } - else - format.html { render :action => "edit" } - format.json { render :json => @post.errors, - :status => :unprocessable_entity } - end - end -end -</ruby> +h4. Going Deeper into REST -In the +update+ action, Rails first uses the +:id+ parameter passed back from -the edit view to locate the database record that's being edited. The -+update_attributes+ call then takes the +post+ parameter (a hash) from the request -and applies it to this record. If all goes well, the user is redirected to the -post's +show+ action. If there are any problems, it redirects back to the +edit+ action to -correct them. +We've now covered all the CRUD actions of a REST app. We did so by +declaring separate routes with the appropriate verbs into ++config/routes.rb+. Here's how that file looks so far: -h4. Destroying a Post +<ruby> +get "posts" => "posts#index" +get "posts/new" +post "posts/create" +get "posts/:id" => "posts#show", :as => :post +get "posts/:id/edit" => "posts#edit" +put "posts/:id" => "posts#update" +delete "posts/:id" => "posts#destroy" +</ruby> -Finally, clicking one of the +destroy+ links sends the associated id to the -+destroy+ action: +That's a lot to type for covering a single *resource*. Fortunately, +Rails provides a +resources+ method which can be used to declare a +standard REST resource. Here's how +config/routes/rb+ looks after the +cleanup: <ruby> -def destroy - @post = Post.find(params[:id]) - @post.destroy +Blog::Application.routes.draw do - respond_to do |format| - format.html { redirect_to posts_url } - format.json { head :no_content } - end + resources :posts + + root :to => "welcome#index" end </ruby> -The +destroy+ method of an Active Record model instance removes the -corresponding record from the database. After that's done, there isn't any -record to display, so Rails redirects the user's browser to the index action of -the controller. +If you run +rake routes+, you'll see that all the routes that we +declared before are still available, and the app still works as before. + +<shell> +# rake routes + posts GET /posts(.:format) posts#index + POST /posts(.:format) posts#create + new_post GET /posts/new(.:format) posts#new +edit_post GET /posts/:id/edit(.:format) posts#edit + post GET /posts/:id(.:format) posts#show + PUT /posts/:id(.:format) posts#update + DELETE /posts/:id(.:format) posts#destroy + root / welcome#index +</shell> + +TIP: In general, Rails encourages the use of resources objects in place +of declaring routes manually. For more information about routing, see +"Rails Routing from the Outside In":routing.html. h3. Adding a Second Model -Now that you've seen what a model built with scaffolding looks like, it's time to -add a second model to the application. The second model will handle comments on +It's time to add a second model to the application. The second model will handle comments on blog posts. h4. Generating a Model -Models in Rails use a singular name, and their corresponding database tables use -a plural name. For the model to hold comments, the convention is to use the name -+Comment+. Even if you don't want to use the entire apparatus set up by -scaffolding, most Rails developers still use generators to make things like -models and controllers. To create the new model, run this command in your -terminal: +We're going to se the same generator that we used before when creating +the +Post+ model. This time we'll create a +Comment+ model to hold +reference of post comments. Run this command in your terminal: <shell> $ rails generate model Comment commenter:string body:text post:references @@ -1015,7 +1245,6 @@ You'll need to edit the +post.rb+ file to add the other side of the association: <ruby> class Post < ActiveRecord::Base - validates :name, :presence => true validates :title, :presence => true, :length => { :minimum => 5 } @@ -1034,9 +1263,7 @@ h4. Adding a Route for Comments As with the +welcome+ controller, we will need to add a route so that Rails knows where we would like to navigate to see +comments+. Open up the -+config/routes.rb+ file again. Near the top, you will see the entry for +posts+ -that was added automatically by the scaffold generator: <tt>resources -:posts</tt>. Edit it as follows: ++config/routes.rb+ file again, and edit it as follows: <ruby> resources :posts do @@ -1054,7 +1281,7 @@ In":routing.html guide. h4. Generating a Controller With the model in hand, you can turn your attention to creating a matching -controller. Again, there's a generator for this: +controller. Again, we'll use the same generator we used before: <shell> $ rails generate controller Comments @@ -1081,40 +1308,33 @@ So first, we'll wire up the Post show template (+/app/views/posts/show.html.erb+) to let us make a new comment: <erb> -<p id="notice"><%= notice %></p> - -<p> - <b>Name:</b> - <%= @post.name %> -</p> - <p> - <b>Title:</b> + <strong>Title:</strong> <%= @post.title %> </p> <p> - <b>Content:</b> - <%= @post.content %> + <strong>Text:</strong> + <%= @post.texthttp://beginningruby.org/ %> </p> <h2>Add a comment:</h2> <%= form_for([@post, @post.comments.build]) do |f| %> - <div class="field"> + <p> <%= f.label :commenter %><br /> <%= f.text_field :commenter %> - </div> - <div class="field"> + </p> + <p> <%= f.label :body %><br /> <%= f.text_area :body %> - </div> - <div class="actions"> + </p> + <p> <%= f.submit %> - </div> + </p> <% end %> <%= link_to 'Edit Post', edit_post_path(@post) %> | -<%= link_to 'Back to Posts', posts_path %> | +<%= link_to 'Back to Posts', posts_path %> </erb> This adds a form on the +Post+ show page that creates a new comment by @@ -1489,6 +1709,7 @@ class Post < ActiveRecord::Base has_many :comments, :dependent => :destroy has_many :tags + attr_protected :tags accepts_nested_attributes_for :tags, :allow_destroy => :true, :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } } |