MVC

How the web works (recap)

(browser makes a request, server responds with a response, usually HTML). Repeat
From sinatra to Rails, this remains the same. The changes are only inside the server

What is MVC

Models, you already know them
Views, you already know them, but there are new things in Rails
Controllers: handle user requests, by interacting with models, and rendering views to generate the final HTML response

Routes

Routes go in config/routes.rb, and link to controller actions

get '/', to: 'test#my_action' links to TestController#my_action

Route convetions

In sinatra you did something like this:

* GET  /users            (index)
* GET  /users/:id        (show)
* POST /users            (create)
* POST /users/:id/edit   (edit)
* POST /users/:id/delete (destroy)

LIVE DEMO: sinatra-almost-rails app

Introduce PUT and DELETE

Introducing PUT and DELETE, you can shorten this to:

* GET    /users     (index)
* GET    /users/:id (show)
* PUT    /users/:id (update)
* DELETE /users/:id (destroy)

Now, we usually want the following pages:

a list of users
show a single user
show a form to create a new user (which goes to POST when submitting)
show a form to edit an existing user (which goes to PUT when submitting)
(delete action, which does not require a page)

How could we model this?

* GET    /users          (index)
* GET    /users/new      (new)
* POST   /users          (create)
* GET    /users/:id      (show)
* GET    /users/:id/edit (edit)
* PUT    /users/:id      (update)
* DELETE /users/:id      (destroy)

So how about we follow this convention all the time?

get  '/users',          to: 'users#index'
get  '/users/new',      to: 'users#new'
post '/users',          to: 'users#create'
get  '/users/:id',      to: 'users#show'
get  '/users/:id/edit', to: 'users#edit'
put  '/users/:id',      to: 'users#update'
delete '/users/:id',    to: 'users#destroy'

Which in rails translates to:

resources :users

Convention over Configuration

Some you have already seen from ActiveRecord:

User model relates to the users table
belongs_to :user refers to a user_id column, and links to an instance of the User model
has_many :users, is the plural form of :user, so it links to instances of the User model

Some other conventions:

UsersController should handle the User model
Resource actions are [:index, :show, :new, :create, :edit, :update, :destroy]
views are in app/views/controller_name/action_name.erb
main layout is in app/views/layouts/application.html.erb

How to create a Rails project

$ gem install rails
$ rails new my_project

Rails Structure

(explain this directories for a bit)

* app/
  * assets/
  * controllers/
  * models/
  * views/
* config/
  * initializers/
  * routes.rb
  * database.yml
* db/ # (same as before)
* lib/

Route helpers

You currently do this:

<a href="/posts/<%= post.id %>">Post Title</a>

But Rails routes make this easier:

<a href="<%= post_path(post) %>Post Title</a>"

Some other helpers:

get  '/users',          to: 'users#index'    => users_path
get  '/users/new',      to: 'users#new'      => new_user_path
post '/users',          to: 'users#create'   => users_path (and method: :post)
get  '/users/:id',      to: 'users#show'     => user_path(user)
get  '/users/:id/edit', to: 'users#edit'     => edit_user_path(user)
put  '/users/:id',      to: 'users#update'   => user_path(user) (and method: :put)
delete '/users/:id',    to: 'users#destroy'  => user_path(user) (and method: :delete)

or any other:

get '/something', to: 'my_controller#my_action', as: :custom

custom_path
#=> '/something'

naps62/cs2015-rails-presentation.md

MVC