Creating a Ruby Weblog in 10 Minutes

Contributed by Brian Leonard, maintained by Gail Chappell
December 2007 [Revision number: V6.0-6]

In this tutorial, you use the Ruby support in the NetBeans IDE to create and run a simple web application. The example shows how to create a Ruby web log. You follow the basic workflow of creating the model, adding a controller, and creating a view.

Contents

-	Tutorial Requirements
-	Creating the Sample Database
-	Creating the Ruby on Rails Project
-	Configuring the Database Environment
-	Creating the Model
-	Migrating the Database
-	Creating a Controller
-	Running the Application
-	Doing More: Adding Another Field
-	Doing More: Validating Input
-	Doing More: Making the List Look More Like a Blog

Tutorial Requirements

This tutorial requires the following technologies and resources:

• A database server
• NetBeans IDE 6.0 with Ruby support

Note: This tutorial, which is written for Rails 1.2.5, involves scaffolding. As of Rails 2.0, scaffolding is no longer supported.

Creating the Sample Database

Note: This tutorial uses the MySQL database server. See the Installing and Configuring Ruby Support article for information about using a MySQL database server in a Ruby application. The article also describes how to use the Java DB database server instead.

Before you create the Ruby on Rails project, create a rubyweblog_development database, as described below.

1. Open a command window.
2. If it has not already been started, start the MySQL database server.
3. Type the following command to create the development database and press Enter.

   mysqladmin -u root -p create rubyweblog_development

   Note: If the root user does not have a required password, omit the -p argument.

Creating the Ruby on Rails Project

You begin by creating a Ruby on Rails project. By default, the application is created in a directory structure that conforms to the Ruby on Rails project conventions for applications.

1. In the NetBeans IDE, choose File > New Project.

2. Select Ruby in the Categories field and Ruby on Rails Application in the Projects field. Click Next.

   Note: The first time that you create a Ruby project in the IDE, the IDE checks if you have any other Ruby installations in addition to the bundled JRuby software. If you do, the IDE displays a dialog box asking you to select which software to use. Choose JRuby if you want to use the bundled JRuby interpreter, or choose your Ruby installation if you prefer to use it instead. For more information, see Configuring the IDE to Use Your Own Ruby Installation in the Installing and Configuring Ruby tutorial.
3. Type rubyweblog in the Project Name field. Accept all the other default settings.

4. Click Finish to create the new project.

   The IDE creates the project directory with the same name as your project. You see the following:

   • The basic categories of the application in the Projects window. Of particular interest are the Controllers, Models, and Views nodes. In this tutorial, you follow the basic workflow of creating the model, adding a controller, and creating a view.
   • A list of files that are part of the application in the Output window. You can click a link in the Output window to open a file in the editing area.
   • The database.yml file in the editing area.

Configuring the Database Environment

The next step is to edit the file database.yml, which is already configured to use the MySQL adapter and the development database. You do not need to do any configuration unless the root user requires a password.

1. In the editing area, edit the database.yml by providing the password in the development configuration.

2. Save and close the database.yml file.

   Note: If your operating system's host file does not contain localhost, use 127.0.0.1 instead.

Creating the Model

Here you use the Rails Generator to create a model for the application. The rubyweblog application requires a Post model for storing instances of blog posts.

1. In the Projects window, right-click the Models node and choose Generate.

2. In the Rails Generator dialog box, type Post title:string in the Arguments field and click OK.

   The Rails Generator creates a model named Post. The Output window lists the files that are created as part of the model generation:

   • app/models/post.rb. A file that holds the methods for the Post model. This file is also opened in the editing area.
   • test/unit/post_test.rb. A unit test for checking the Post model.
   • test/fixtures/posts.yml. A test fixture for populating the model.
   • db/migrate/migrate/001_create_posts.rb. A migration file for defining the initial structure of the database.

Migrating the Database

The file that you work with next is the migration file, 001_create_posts.rb.

1. In the Output window, click the link for the 001_create_posts.rb file.

   The file opens to show the self.up method, which creates a table called posts, and the self.down method, which tears the posts table down, as shown in the following code sample:

   Code Sample 1: Code for 001_create_posts.rb

   class CreatePosts < ActiveRecord::Migration
     def self.up
       create_table :posts do |t|
         t.column :title, :string
       end
     end
   
     def self.down
       drop_table :posts
     end
   end

   
   

2. In the Projects window, right-click the rubyweblog node and choose Migrate Database > To Current Version.

   This action updates the the database to include the posts table. The Output window indicates when the migration is complete.

Creating a Controller

Now you use the Rails Generator to create a controller to interact with the Post model. In this tutorial, you add scaffolding code, which provides a simple CRUD interface for creating, reading, updating, and deleting entries in the blog.

1. In the Projects window, right-click the Controllers node and choose Generate.

2. In the Rails Generator dialog box, type Blog in the Name field. Leave the Views field blank. Click OK.

   This action creates the file blog_controller.rb and opens the file in the editing area. A blog_controller.rb node is added under the Controllers node in the Projects window.

3. Edit blog_controller.rb by adding the following scaffolding code, which provides a simple CRUD application around the Post model:

   Code Sample 2: Code for blog_controller.rb

   class BlogController < ApplicationController
     scaffold :post
   end

Running the Application

Now test the application.

1. Under the Configuration node, open routes.rb. Find the line:

   # map.connect '', :controller => "welcome"
   	

2. Edit the line by removing the comment sign (#) and changing welcome to blog.

3. Expand the Public node, right-click index.html and choose Delete.

   index.html displays a default Welcome page, which is not what you want. By deleting index.html, Rails looks in routes.rb to figure out what page to display, which you set to the blog in the previous step.

4. Choose File > Save All.

5. Click the Run Main Project button in the toolbar.

   This action starts the WEBrick server, which is part of the Ruby on Rails framework, and launches the web browser. Following is the first page of the application.

   Figure 1: rubyweblog Home Page

   
   

6. Click the New post link to display the second page of the application, shown below.

   Figure 2: Page for Creating a New Post

   
   

7. Enter a title and click Create.

   Following is a sample blog post.

   Figure 3: Successful Creation of Blog Post

   

Doing More: Adding Another Field

Here you add another field so that, in addition to the Title field, the posts table includes a Body column for providing the text of the blog. The steps for creating a field should be familiar by now.

1. Right-click the Database Migrations node and choose Generate. In the Rails Generator dialog box, type AddBody in the Arguments field and click OK.

   The IDE creates the versioned migration script 002_add_body.rb and opens the file in the editing area.

2. Open up a line under def self.up, type mcol, and press Tab.

   The IDE replaces the mcol trigger with the following code template with 3 parameters:

   add_column :table, :column, :string

3. Type posts to replace the first parameter, then press Tab. Type body and press Tab again. Then type text to replace the third parameter. The line should look like the following statement:

   add_column :posts, :body, :text

   This migration adds a body column to the posts table.
4. Choose File > Save All.

5. Right-click the rubyweblog node and choose Migrate Database > To Current Version.

   Alternatively, right-click in the source file and choose Run from the pop-up menu.

6. Return to the browser and click the New Post link to see how Ruby recognizes the new body field, shown in the following figure.

   Figure 4: New Post With Body Field

   

7. Create a few more blog entries. For example:

   Figure 5: More Blog Posts

   

Doing More: Validating Input

Here, you add code to the Post class to ensure that the users provide values for both the title and the body fields.

1. In the Projects window, expand the Models node and double-click post.rb to open the file in the editor.

2. Open up a line inside the Class definition, type vp, then press Tab.

   The IDE replaces vp trigger with the following code template:

   validates_presence_of :attribute

3. Type title, :body. The code should look like the following statement:

   validates_presence_of :title, :body

4. Run the application, click New Post, and click Create.

   The application now reports that the title and body cannot be blank.

Doing More: Making the List Look More Like a Blog

So far, the scaffold method used in the BlogController created a basic CRUD application that enabled you to easily test the Post model. Now, you generate the same views used by the scaffold method so that you can customize the user interface.

1. In the Projects window, right-click the Views node and choose Generate.
2. In the Rails Generator dialog box, choose scaffold from the Generate drop-down list.

3. Type Post in the Model Name field and Blog in the Controller Name field. Leave the Actions field blank. Select Overwrite to force the BlogController to be regenerated, and then click OK.

   The IDE creates a view for the Post model and lists the contents in the Output window.

4. Expand Views > blog and open list.rhtml, which is used to show the list of blog entries. Delete the <h1> and <table> tags and replace them with the following code:

   Code Sample 4: Code for list.rhtml

   <h1>The Ruby Blog</h1>
   
   <% @posts.each do |post| %>
     <h2><%= post.title %></h2>
     <p><%= post.body %></p>
     <small> <%= link_to 'Permalink', :action => 'show', :id => post %></small>
     <hr>
   <% end %>

   
   

   For each instance of a post action, this code produces a title, body, and Permalink, as shown in Figure 6.

   Tip: liai (link with an action and index) is the trigger for the following code template:

   <%= link_to "link text...", :action => "edit", :id => @item %>

5. Run the application to see the new interface for the Post model.

   Figure 6: New and Improved Model Interface

   

6. To display the blog with the most recent entry first, reverse the sort order by adding .reverse to the end of @posts in list.rhtml:

   	  <% @posts.reverse.each do |post| %>
   	  

   When you save the file and refresh your browser, the blog displays as shown in the following figure.

   Figure 7: Blog Posts in Reverse Order

   

Next Steps

• To continue with the Ruby web log tutorial and learn more about Ruby support in the NetBeans IDE, go to Building Relationships Between Rails Models.

• To obtain support and stay informed of the latest changes to the NetBeans Ruby development features, join the users@ruby.netbeans.org and dev@ruby.netbeans.org mailing lists.

• To submit your own NetBeans Ruby tutorial, visit the NetBeans Community Docs page.