Rails-Talk.md

Rails

Getting Started

rails new Dema
bundle install

rails server

• Show terminal during GET request
• Leave running on another desktop

Important Files

File	use
Gemfile	Shows what gems need to be loaded to run the application
config/environments/*	Environment specific variables for the development, test and production environments
config/routes.rb	Associates each route with an action
config/secrets.yml	YAML file containing things like private keys and api keys
db/schema	Stores the database schema, should not be edited
db/migrations/*	Scripts to migrate the database, i.e. add, modify or remove tables

app Directory Layout

Directory	use
assets	images, javascripts, stylesheets, etc.
controllers	Classes used to define actions for routes
helpers	utility classes, usually to help the view and controller
models	Database objects
views	Page layout written in eruby

MVC

Model (ActiveRecord)

• Contains data for the application (often linked to a database)
• Contains state of the application (e.g. what orders a customer has)

View (ActionView)

• Presentation of data
• Generates the user interface which presents data to the user
• Does not do any additional work

Controller (ActionController)

• Directs traffic
• Receive events from the outside world (usually through views)
• Interact with the model
• Displays the appropriate view to the user

Model

rails generate scaffold user name:string email:string student_number:integer

See what it generates

less db/schema.rb
less db/migrations/

Run sql

rails db

.tables
.schema users
select * from users;

open rails console

User.create(name: 'Conor Loney', email: 'thescratchguy@scratch.mit.edu', student_number: 12)

conor = User.find_by name: 'Conor Loney'
conor.name

conor.update student_number: 2

Ruby Syntax

def hello_world
  puts("Hello, World!")
  puts "Hello, World!"
end

xs = [1,2,3]
xs.map do |x|
  x = x + 1
  x = x * x
end

xs.map {|x| x = x * x}

Controllers

rails generate controller pizza

vi app/controllers/pizza_controller.rb

# app/controllers/pizza_controller.rb 
class PizzaController < ApplicationController
    def index

    end
end

# app/views/pizza/index.html.erb
<h1>Pizza</h1>

<h3><%= link_to 'Just Eat', 'ttp://www.just-eat.ie' %></h3>

Views

Template Engine

app/views/application.html.erb