intro to rails

rails basics

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how do browsers work?

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what does rails do?

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MODELS, Views, Controllers

rMVC

(and routes)

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router

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ROUTER

the router looks at the incoming request and sends it to the right controller.

Example:

myapp.com/users/1/edit

goes to the users controller, edit action(and sends a ‘parameter’ for user_id=1 as )

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ROUTER

/users users#index list all users

/users/1 users#show show user with id 1

/users/new users#new make a new user

/users/1/edit users#edit edit user with id 1

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SAMPLE ROUTE

RedditDemo::Application.routes.draw  do    match  'users/'  =>  'users#index'    root  to:  'users#index'end

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controller

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CONTROLLER

The controller orchestrates the request.

It communicates with models to gather and manipulate data.

It then passes that data to the view.

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CONTROLLER ACTIONS

Controllers have multiple actions.

The standard ‘restful’ actions are:

indexshowcreateneweditupdatedestroy

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SAMPLE CONTROLLER

class  UsersController  <  ActionController::Base    def  index        @users  =  User.all    endend

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models

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MODELS

Models represent the nouns and data in your application.

They make sure stored data is valid, and perform calculations/analysis.

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DATABASES

•Store our model data (in rows), and define the attributes (columns).

•We manage changes in our database with migrations.

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MIGRATION

>> rails generate migration CreateUsers

class CreateUsers < ActiveRecord::Migration

def change

create_table :users do |t|

t.string :first_name

t.string :last_name

t.string :netid

t.timestamps

end

end

end

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DATABASE

id first_name last_name netid

1

2

3

Adam Bray alb64

Vladimir The Bear vtb39

Charlie The Horse cth44

users

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DATABASE

id first_name last_name netid

1

2

3

Adam Bray alb64

Vladimir The Bear vtb39

Charlie The Horse cth44

users

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ADDING ANOTHER COLUMN

rails generate migration AddClassYearToUsers class_year:integer

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DATABASE

id first_name last_name netid class_year

1

2

3

Adam Bray alb64 1995

Vladimir The Bear vtb39 2015

Charlie The Horse cth44 2016

users

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SAMPLE MODEL

class  User  <  ActiveRecord::Baseend

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views

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VIEWS

Views are templates for how your web pages look.

Variables created in the respective controller are used to insert relevant information into the template.

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VIEWS

Views use Embedded RuBy (ERB) to substitute data into the template.

<% #ruby here is run, but not output %>

<%= #ruby here is run and output %>

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SAMPLE VIEW

<%  @users.each  do  |user|  %>    <%=  user.name  %><%  end  %>

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