Why do we need organization?

• Code grows over time
• Code becomes unmanageable
• Simple Scripts Grow From 100 Lines to 4000 Lines

We need organization!

• Convention over configuration
• One less decision for you to make
• Allows you to work with other teams very easily
• A place for everything and everything in its place.

MVC The Rails Way

• Model
• View
• Controller

Models

• Represent "things" in our application
• Usually stored in the database
• Live in `app/models`

Model Example - Twitter

• What things do we need in a twitter application?
• Tweet
• Text
• user
• User
• Username
• Password

Tweet Model

class Tweet < ActiveRecord::Base
  belongs_to :user
end
          

class User < ActiveRecord::Base
  has_many :tweets
  has_many :followers
  has_many :followed_users

  def recent_tweets
    tweets.where("created_at > ?", 2.weeks.ago)
  end
end
          

Views

• Display our models!
• Use HTML for browser rendering.
• Used ERB to show anything from "code"
• Live in `app/views`

Tweet View

<h1>Tweet from <%= @tweet.username %></h1>
<p><%= @tweet.text %></p>
          

Combining Views

Controllers

• Traffic Cops
• Line up information and send it to the view

Example Controller

http://localhost:3000/tweets

class TweetsController < ApplicationController
  def index
    @tweets = Tweets.all
  end
end
          

The Flow

• User visits a URL
• Controller is activated; looks up the model
• Controller passes the model to the view
• View is rendered for the user to see

Recap

• Models represent data in the real world
• Views show your models
• Controllers connect models to views

Have fun!