Rails Quiz Correction

rails_quiz_correction.rb

# Q1 - How do you create a Rails app?
# TODO: rails?
rails new project-name --database=postgresql

# Q2 - How do you start coding a Rails project? Give the right sequence.
# '1. Coding the views?'
# '2. Coding the controllers?'
# '3. Coding the models?'
# TODO: 1, 2, 3?
3,2,1

# Q3 - How do you generate a Song model with a title and a year?
# TODO: rails?
rails g model song title:string year:integer
# What are the 2 created files?
# TODO:
1. app/models/song.rb
2. db/migrate/8765678909876_create_songs.rb

# What is the rails command you should type then?
# TODO: rails?
rails db:migrate

# Q4 - How do you add a category (ex: “rock” , “electro” , etc..) to your songs table using the right Rails generator?
# TODO: rails?
rails g migration AddCategoryToSongs category:string
# add_column :songs, :category, :string

# What is the created file?
# TODO:
timestamp_add_category_to_songs.rb

# What is the rails command you should type again?
# TODO: rails?
rails db:migrate

# Q5 - Add a presence validation on song titles & crash-test your model in the console
class Song < ApplicationRecord
  # TODO
  validates :title, presence: true
end

# Now crash-test your model:
# TODO:
new_song = Song.new(title: 'some title', category: 'blues')
new_song.valid? => true
test_song = Song.new(category: 'some title')
test_song.valid?
test_song.save
test_song.errors
# Q6 - What is the Rails flow you need to follow again and again? Give the correct order

# 1. The Router is routing the HTTP request to "controller#action".
# 2. The action is getting data from models.
# 3. Everything starts with an HTTP Request.
# 4. The action is rendering the view.

# TODO: 1, 2, 3, 4?
3,1,2,4

# Q7 - What are the 4 different parts inside an HTTP request?
verb/method # GET/POST/PUT/PATCH/DELETE
path # URL
headers
body

# Q8 - Are the HTTP requests in the following 2 routes the same? Why?
# get "/songs" => "songs#index"
# post "/songs" => "songs#create"

# TODO:
No - they share the same path, but have different verbs.

# Q9 - What’s the difference between a GET and a POST request?

# TODO:
get reads data and post sends data

# Q10 - Complete the controller code using the correct params key?
# GET /search?query=thriller
class SongsController < ApplicationController
  def search
    # TODO
    @songs = Song.where(title: params[:query])
  end
end

# Q11 - Complete the controller code using the correct params key?
# GET /songs/named/thriller
class SongsController < ApplicationController
  def search
    # TODO
    @songs = Song.where(title: params[:name])
  end
end

# Q12 - What are the 7 CRUD routes generated by the resources method in Rails?
get 'songs', to: 'songs#index'
get 'songs/:id', to: 'songs#show'
get 'songs/new', to: 'songs#new'
post 'songs', to: 'songs#create'
get 'songs/:id/edit', to: 'songs#edit'
patch 'songs/:id', to: 'songs#update'
delete 'songs/:id', to: 'songs#destroy'

# Q13 - How do you print your routes and their URL prefix helpers?
# TODO:
rails routes
# Q14 - How do you generate a controller for your songs?
# TODO: rails?
rails generate controller songs
# Q15 - Implement the Read actions in your songs controller?
class SongsController < ApplicationController
  # TODO: Implement the read actions
  def index
    @songs = Song.all
  end

  def show
    @song = Song.find(params[:id])
  end
end

# Q16 - What are the 2 requests needed to create a new song? Implement the songs#new and songs#create actions.
class SongsController < ApplicationController
  def new
    # TODO
    @song = Song.new
  end

  def create
    # TODO
    @song = Song.new(song_params)
    if @song.save
      redirect_to song_path(@song)
    else
      render :new
    end
  end

  private
  def song_params
    # TODO
    params.require(:song).permit(:title, :year, :category)
  end
end

# Q17 - Why do we have to filter parameters using “strong params” in the controller?
# TODO:
For security purposes, Rails will only permit identified params
# Q18 - Hard question: What is the HTML generated?
# @song = Song.new
# TODO:
Ruby object

# Now what is the HTML generated by?
# <%= form_for @song do |f| %>
#   <%= f.text_field :title %>
#   <%= f.submit %>
# <% end %>

# Fill in the blanks
<form action="songs/new" method="post">
  <input type="text" name="song[title]" value="">
  <input type="submit" value="Create song">
</form>

# Q19 - Hard question: What is the HTML generated?
# @song # => <#Song: id: 18, title: "Hey jude", year: 1968, category: "rock">

# <%= form_for @song do |f| %>
#   <%= f.text_field :title %>
#   <%= f.submit %>
# <% end %>

<form action="/songs/18" method="patch">
  <input type="text" name="song[title]" value="Hey Jude">
  <input type="submit" value="Update song">
</form>

# Q20 - Now you want to add reviews to your app. Here are some constraints
# Generate your Review model in the terminal. It should have only a content:string and a song:references (= the foreign key).
# TODO: rails?
rails g model review content:string song:references
# Run the migration
# TODO: rails?
rails db:migrate

# Add validation/associations

# - Add a validation for the presence of a content
# - Add associations between Review and Song

class Song < ApplicationRecord
  # TODO
  has_many :reviews
end

class Review < ApplicationRecord
  # TODO
  belongs_to :song
  validates :content, presence: true
end

# TODO: Generate the reviews controller
rails g controller reviews
# Add the necessary routes
resources :songs do
  # TODO
  resources :reviews, only: [:new, :create]
end

# Now code your controller
class ReviewsController < ApplicationController
  before_action :set_song
  def new
    # TODO
    @review = Review.new
  end

  def create
    # TODO
    @review = Review.new(review_params)
    @review.song = @song
    if @review.save
      redirect_to song_path(@song)
    else
      render :new
    end
  end

  private

  def set_song
    @song = Song.find(params[:song_id])
  end

  def review_params
    params.require(:review).permit(:content)
  end
end

# Add a song's review

<h1><%= @song.title %></h1>
<p><%= @song.year %></p>
<p><%= @song.category %></p>
<h2>Here are the reviews for this song:</h2>
<% @song.reviews.each do |review| %>
  <p><%= review.content %></p>
<% end %>