Day 2 - Intro to Rails
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Intro to Rails
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Transcript of Day 2 - Intro to Rails
Intro to Rails
What do we look for in a framework?
• Please don’t suck– Rails does not suck
• Does it follow Model-View-Controller?– Yes – Since Rails 1 it’s been the standard bearer for how to do MVC on the web, copied in almost every language
• Does it help me avoid repeating myself (DRY)?– Yes
• Is it self documenting?– Yes, it has a set of rules that generally make most documentation unnecessary
• Is it flexible enough to bend to my application needs?– Yes
• Do other people use it?– Good gosh yes
• Will it work with my database?– Yes
• Is it still going to be around in X years?– Ruby has Rails– Python has Django– Groovy has Grails– C# has MVC– PHP has fragmented framework Hell (aka – who knows?)– Java has a few major players (Struts 2, Play, etc)
Request Flow
Rack
Watch this excellent walkthrough of Rack Middleware:
http://railscasts.com/episodes/151-rack-middleware
Summary: It’s a layer of ruby code that passes requests into your app and sends responses back out. You can add layers to do pre/post processing on all requests prior to beginning ANY of your application code.
Before the Request
• Configuration
• Initializers
• Gems
• Environments
• Asset Pipeline
Models / ActiveRecord
class Post < ActiveRecord::Base
belongs_to :category
has_many :tags, through: :posts_tags
validates :title, presence: true
before_save :create_slug, only: :create
scope :newest_first, order(‘created_at DESC’)
scope :active, where(‘active = ?’,true)
scope :newest_active, newest_first.active
scope :search, lambda do |text|
where(‘title LIKE ?’,”%#{text}%”)
end
def create_slug
self.slug = title.downcase.squish.sub(‘ ‘,’-’)
end
end
post = Post.new(title: ‘Some title’)
post.save!
OR
post = Post.create(title: ‘Some title’)
post.slug # some-title
post.id # 1
post.created_at # Created datetime
post.updated_at # Updated datetime
post.title = ‘New title’
post.save!
# Relations
post.tags.first
post.tags.count
post.category.name
post = Post.include(:tags) # Eager load
post =
Post.search(‘some’).newest_active.first
Migrationsclass CreateInitialTables < ActiveRecord::Migration
def up
create_table :posts do |t|
t.string :title
t.text :body
t.string :slug
t.integer :category_id
t.timestamps
end
# … create more tables…
add_index :tags, [:name,:something], unique: true
execute “UPDATE posts SET field = ‘value’ WHERE stuff = ‘happens’”
end
def down
drop_table :posts
end
def change
add_column :posts, :user_id, :integer
end
end$ rake db:migrate
Controllers and REST
Class PostsController < ApplicationController
before_filter :authenticate, only: :destroy
def index # GET /posts
end
def new # GET /posts/new
end
def create # POST /posts
end
def show # GET /posts/:id
end
def edit # GET /posts/:id/edit
end
def update # PUT /posts/:id
end
def destroy # DELETE /posts/:id
end
end
# Routes
resources :posts
OR limit it
resources :posts, only: [:create,:new]
Views
/app/views
/layouts
/application.html.erb
/posts
/new.html.slim
/new.json.rabl
/index.xml.erb
/_widget.html.erb
# slim example
.post
h2=post.title
.body.grid-8=post.body
# erb example
<div class=“post”>
<h2><%=post.title%></h2>
<div class=“body grid-8”>
<%=post.body%>
</div>
</div>
Generators
• rails new .
• rails g scaffold article name content:textpublished_on:date
LET’S WRITE SOME CODE!
