Rails 3

Application Setup

• create project with

rails new my_project
rails -d mysql new my_project  # if you don't want the default sqlite3

• add gem dependencies to Gemfile at the root level
• update config/application.rb to load needed dependencies and update defaults
• double-check /config/initializers and /config/environments
• edit config/database.yml to connect to your database

Notes

Files in lib/ are not automatically loaded, so you need to require them.

In config/environments/development.rb, set

config.action_mailer.perform_deliveries = false

No delivery attempt is performed, but you can still see the mail in the log file to check it looks good

Database Setup

• create database with

rake db:create

Create a table and its controller

rails generate model Article

Edit db/migrate/20100223220648_create_articles.rb to look like this:

class CreateArticles < ActiveRecord::Migration
    def self.up 
        create_table :articles do |t|
            t.string :title
            t.text :body
            t.datetime :published_at
            t.timestamps
        end
    end
    def self.down
        drop_table :articles
    end
end

To create/update the table:

rake db:migrate

To generate the controller:

rails generate controller articles

Make a scaffold

To make a scaffold for the table to allow easy create/update/delete in development:

rails generate scaffold Article title:string body:text published_at:datetime --skip-migration

Update table and scaffold

To modify the table, generate a custom migration:

rails generate migration add_excerpt_and_location_to_articles excerpt:string location:string

creates this migration file db/migrate/20100223232337_add_excerpt_and_location_to_articles.rb:

class AddExcerptAndLocationToArticles < ActiveRecord::Migration
    def self.up
        add_column :articles, :excerpt, :string
        add_column :articles, :location, :string
    end
    def self.down
        remove_column :articles,
        :excerpt remove_column :articles, :location
    end
end

Run rake db:migrate again to update the database.

Now update the scaffold:

rails generate scaffold Article title:string location:string excerpt:string body:text published_at:datetime --skip-migration

Add validations to the model

Edit app/models/article.rb:

class Article < ActiveRecord::Base
    validates :title, :presence => true
    validates :body, :presence => true
end

Other rails commands

rails console
rails dbconsole
rails server
rails runner

Routing

Configured in config/routes.rb

match 'products/:id' => 'products#show'

The url http://localhost:3000/products/8 will be mapped to the show action of the products controller with params[:id] set to 8

To create a link to this route (old way):

link_to "Products", :controller => "products", :action => "show", :id => 1

To restrict the HTTP method, use get or post instead of match:

get 'products/:id' => 'products#show'

To redirect:

match "/foo", :to => redirect("/bar")

Logging

Use these in models, views, controllers to send timestamped messages to the log.

logger.debug "debug message"
logger.info "info message"
logger.warn "something bad"
logger.error "something broke"
logger.fatal "application dead"