Controller

Question 1

What is rails middleware?

Answer 1

Rails middleware allows you to catch request or response before it reaches Rails, and modify it. ( You are in the middle between Rack and Rails).

Question 2

How to add and include your custom middleware?

Answer 2

create app/middlewares/sample.rb

class Sample
  def initialize app
    @app = app
  end

  def call env
    puts "Middleware called"

@app.call(env)   end end

and include config/environments/development.rb

config.middleware.use Sample

Question 3

How to render a concrete template?

Answer 3

template path app/views/my_examples/sample.html.erb
def new
render ‘my_examples/sample’
end

Question 4

How to use a redirect?

Answer 4

redirect_to ‘/animals/new’

Question 5

What are the differences between render and redirect?

Answer 5

1) redirect is a new request, but render just draw the html

Question 6

Can you tell me 6 ways to render a concrete template?

Answer 6

# inside Product controller 
render '/products/index.html.erb'
render 'products/index.html.erb'
render 'products/index.html'
render 'products/index'
render 'index'
render :index

Question 7

How to render partial?

Answer 7

# app/views/my_examples/_partial.html.erb
render partial: '/my_examples/partial'

Question 8

What path returns the following code “render @animal” ?

Answer 8

# AnimalsController
app/views/animals/_animal.html.haml

Question 9

How to render json/xml/text/body/ruby_code/js/html in controller? ( 7 options )

Answer 9

• render json: {a: 1}
• render xml: {a: 1}
• render plain: “Hello” # text
• render body: ‘AAA’
• render html: “<h1> dad </h1>“.html_safe
• render inline: “#{1 + 1}” # ruby
• render js: “alert(‘h’)”

Question 10

How to add a new helper and use it inside the controller?

Answer 10

# app/helpers/sample_helper.rb
module SampleHelper
  def hello
    p 'Hello'
  end
end

inside contoller method
def new
helpers.hello
end

Question 11

How to return nothing? Just a status?

Answer 11

head :ok

Question 12

How to change layout? Or turn off layout?

Answer 12

# app/views/layouts/application.html.erb
render layout: 'sample'
# turn off
render layout: false

Question 13

How to change the response status?

Answer 13

render status: 401

Question 14

How to redirect and send a flash message?

Answer 14

redirect_to ‘/animals/new’, notice: ‘hello’

#

Question 15

How to add your own flash name for redirection?

Answer 15

class ApplicationController < ActionController::Base
  add_flash_types :my_notice
end

redirect_to ‘/animals/new’, my_notice: ‘hello’

#

Question 16

How to share variables between controller and view?

Answer 16

View creates a copy of all instance variables from the controller.

# controller
  def new
    @a = 1
  end
# view

Question 17

How to run something before/after action? (callback)

Answer 17

before_action :say_hello
after_action :say_hello

private

def say_hello
p ‘Hello’ * 100
end

Question 18

How to run something before before_action?

Answer 18

prepend_before_action :before_hello

prepend_after_action :before_hello

Question 19

What is a session?

Answer 19

A session is a concept to store data during one request that you can read during later requests. And typically the session only persists until the user shuts down their browser.

Question 20

What are cookies?

Answer 20

A cookie is a small text file stored in the browser.

Question 21

What are the differences between sessions and cookies?

Answer 21

Session the abstract concept of holding temporary data. Cookies one (common) way of doing it.

In rails they are similar but not the same. session is an entire hash that gets put in the secure session cookie that expires when the user closes the browser ( we store only one cookies which is secure this is session)

Question 22

Where we can store session?

Answer 22

1. Inside cookies
2. Inside the database (activerecord-session_store)
3. Inside the cache ( redis )

Question 23

How to create cookies/session?

Answer 23

# controller
    cookies[:sample] = 'Cookies Hello'
    session[:sample] = 'Session hello'
# view

= cookies[:sample]
= session[:sample]

Question 24

How to clear cookies/session?

Answer 24

cookies[:sample] = ‘Cookies Hello’
session[:sample] = ‘Session hello’

cookies. delete :sample
session. delete :sample

Question 25

What are the biggest disadvantages of using cookies?

Answer 25

1. You can only store about 4kb of data in a cookie.
2. Cookies are sent along with every request you make.
3. (security) If you accidentally expose your secret_key_base, your users can change the data you’ve put inside your cookie

Question 26

What should we include on the controller level?

Answer 26

• Security (authentication, authorization)
• Parsing and white-listing parameters
• Loading or instantiating the model ( or services )
• Deciding which view to render (
  or how are we going to show result and error )