Day 2 - Intro to Rails
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Introduction to Ruby on Rails from my Ruby on Rails and PostgreSQL - Intro to Advanced class in August 2014.
![Migrations
class 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](https://image.slidesharecdn.com/day2-introtorails-150401222139-conversion-gate01/85/Day-2-Intro-to-Rails-7-320.jpg)
![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]](https://image.slidesharecdn.com/day2-introtorails-150401222139-conversion-gate01/85/Day-2-Intro-to-Rails-8-320.jpg)
![NoSQL for great good [hanoi.rb talk]](https://cdn.slidesharecdn.com/ss_thumbnails/kvs-hanoirb-150728163935-lva1-app6891-thumbnail.jpg?width=560&fit=bounds)
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Day 2 - Intro to Rails
- 2. 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)
- 3. Request Flow
- 4. 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.
- 5. Before the Request • Configuration • Initializers • Gems • Environments • Asset Pipeline
- 6. 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
- 7. Migrations class 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
- 8. 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]
- 9. 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>
- 10. Generators • rails new . • rails g scaffold article name content:text published_on:date
- 11. LET’S WRITE SOME CODE!
Editor's Notes
- #4: This is a bad diagram because I tried to use the built in tools in power point. I need to update it. In reality the View arrow should be going back through Rack to the Browser.