Braintube

Installation

Since Rails is now in Debian Unstable(sid), not much to say about installation. It’s as easy as:

apt-get install rails

Database

The blog application needs two tables: posts, comments. Following the Rails recommended table and column naming conventions is a good idea and will save even more time later. Every table should be named in the plural, have a primary key called “id”, set as auto increment. Links to other tables should be in the form “singualOfForeignTableName_id”. Rails will automatically maintain fields called created_at/created_on and/or updated_at/updated_on(timestamp). A field called lock_version(integer default of 0) should also be included to allow Rails to do optimistic locking in a multi-user system.

Creating the Database and Tables

create database Blog;

CREATE TABLE `posts` (
    `id` smallint(5) unsigned NOT NULL auto_increment,
    `title` text NULL default '',
    `body` text NULL default '',
    `created_on` timestamp(14) NOT NULL,
    `updated_on` timestamp(14) NOT NULL,
    PRIMARY KEY (`id`)
    ) TYPE=MyISAM COMMENT='List of posts';

CREATE TABLE `comments` (
    `id` smallint(5) unsigned NOT NULL auto_increment,
    `title` text NULL default '',
    `body` text NULL default '',
    `post_id` smallint(5) unsigned NOT NULL,
    `created_on` timestamp(14) NOT NULL,
    `updated_on` timestamp(14) NOT NULL,
    PRIMARY KEY (`id`),
    INDEX `post_id` (`post_id`)
    ) TYPE=MyISAM COMMENT='List of comments';

Rails Setup

Rails generates a good bit of code for you. Now that we have our database/tables in place we can run the Rails script to create our initial Blog application shell. The following command will create a Blog subdirectory
and application shell.

$ rails Blog

Now we need to tell Rails how to connect to our database by editing the database.yml file.

$ cd Blog
$ vi config/database.yml

The file will look something list this:

development:
	adapter: mysql
 	database: rails_development
 	host: localhost
 	username: root
 	password: 

test:
 	adapter: mysql
 	database: rails_test
 	host: localhost
 	username: root
 	password:

production:
	adapter: mysql
	database: rails_production
	host: localhost
	username: root
	password:

You will need to edit the development section to something like this:

development:
	adapter: mysql
	database: Blog
	host: localhost
	username: root
	password:

change your database/host/username/password as appropriate.
Next we will run a few more code generation script to produce a model and controller shell for our posts table.

$ ruby script/generate model Post
$ ruby script/generate controller post

The model name must start with a capital letter and should be the singular name of the related table.
Now we need to link our controller to the model. Edit the post_controller.rb that was generated for you:

$ vi app/controllers/post_controller.rb

Adding model:

class PostController < ApplicationController
	model :post
end

We are now ready to test the application. Rails will run under Apache, but for this example we will use the build in WEBrick http server. In the /Blog directory:

$ ruby script/server

You should now be able to connect to your application from http://localhost:3000 and then access the application http://localhost:3000/post.

Unknown action

No action responded to index

Not very nice, but it’s working. Lets make it nicer by allowing Rails to fill in the details.
Edit post_controller.rb again and add “scaffold :post”.

class PostController < ApplicationController
	model :post
	scaffold :post
end

Now access http://localhost:3000/post/

Listing posts
Title 	Body 	Created on 	Updated on

New post

You’ve got a functioning application. More to come.