Route definition in routes.rb in Ruby on Rails - Mini Project: Build & Apply

Route definition in routes.rb

📖 Scenario: You are building a simple blog application using Ruby on Rails. You need to define routes so that users can visit pages to see all posts, view a single post, create a new post, and edit existing posts.

🎯 Goal: Define routes in the config/routes.rb file to connect URL paths to controller actions for posts.

📋 What You'll Learn

Create a root route that points to the posts#index action

Define a route for GET /posts to list all posts

Define a route for GET /posts/:id to show a single post

Define a route for GET /posts/new to show the new post form

Define a route for GET /posts/:id/edit to show the edit form

💡 Why This Matters

🌍 Real World

Defining routes is essential in Rails apps to connect URLs to the code that handles requests, like showing pages or submitting forms.

💼 Career

Rails developers must know how to configure routes to build web applications that respond correctly to user navigation and actions.

1

Set up the root route

In the config/routes.rb file, write a line to set the root route to the posts#index action.

Ruby on Rails

# Your code here to set root route

Hint

The root route uses the root method followed by the controller and action in quotes.

2

Add route for listing all posts

Add a route for GET /posts that maps to the posts#index action using the get method.

Ruby on Rails

Rails.application.routes.draw do
  root 'posts#index'
  # Add route for GET /posts here

Hint

Use get '/posts', to: 'posts#index' to define this route.

3

Add routes for showing, creating, and editing posts

Add routes for these paths and actions using get:

• GET /posts/:id to posts#show
• GET /posts/new to posts#new
• GET /posts/:id/edit to posts#edit

Ruby on Rails

Rails.application.routes.draw do
  root 'posts#index'
  get '/posts', to: 'posts#index'
  # Add routes for show, new, and edit actions here

Hint

Use get with the path and to: option for each route.

4

Complete the routes file

Ensure the config/routes.rb file has all the routes inside the Rails.application.routes.draw do ... end block exactly as specified.

Ruby on Rails

Rails.application.routes.draw do
  root 'posts#index'
  get '/posts', to: 'posts#index'
  get '/posts/:id', to: 'posts#show'
  get '/posts/new', to: 'posts#new'
  get '/posts/:id/edit', to: 'posts#edit'
  # Confirm all routes are inside the block

Hint

Make sure all routes are inside the Rails.application.routes.draw do ... end block.

Practice

1. What is the purpose of defining routes in the routes.rb file in a Rails application?

easy

A. To manage user sessions

B. To write database queries

C. To style the web pages

D. To connect URLs to specific controller actions

Solution

1. Step 1: Understand the role of routes in Rails

   Routes define how incoming web requests are matched to controller actions.

2. Step 2: Identify the correct purpose

   Connecting URLs to controller actions allows the app to respond correctly to user requests.

3. Final Answer:

   To connect URLs to specific controller actions -> Option D

4. Quick Check:

   Routes link URLs to actions [OK]

Hint: Routes map URLs to controller actions [OK]

Common Mistakes:

• Confusing routes with database queries
• Thinking routes handle styling
• Assuming routes manage sessions

2. Which of the following is the correct syntax to define a GET route for the URL /home that maps to the index action of the pages controller?

easy

A. route get '/home' => 'pages#index'

B. get 'pages#index', to: '/home'

C. get '/home', to: 'pages#index'

D. post '/home', to: 'pages#index'

Solution

1. Step 1: Recall the syntax for GET routes in Rails

   The correct syntax is get 'url', to: 'controller#action'.

2. Step 2: Match the URL and controller#action correctly

   get '/home', to: 'pages#index' correctly uses get '/home', to: 'pages#index'.

3. Final Answer:

   get '/home', to: 'pages#index' -> Option C

4. Quick Check:

   GET route syntax = get 'url', to: 'controller#action' [OK]

Hint: Use get 'url', to: 'controller#action' for GET routes [OK]

Common Mistakes:

• Swapping URL and controller#action positions
• Using post instead of get for GET routes
• Incorrect syntax like 'route get'

3. Given the following route definition in routes.rb:

resources :articles, only: [:index, :show]

What URLs will be available and which controller actions will they map to?

medium

A. /articles (GET) -> articles#index and /articles/:id (GET) -> articles#show

B. /articles/new (GET) -> articles#new and /articles/:id/edit (GET) -> articles#edit

C. /articles (POST) -> articles#create and /articles/:id (PATCH) -> articles#update

D. /articles/:id (DELETE) -> articles#destroy and /articles (GET) -> articles#index

Solution

1. Step 1: Understand the resources with only option

   It limits routes to only index and show actions.

2. Step 2: Identify URLs and actions for index and show

   index maps to GET /articles, show maps to GET /articles/:id.

3. Final Answer:

   /articles (GET) -> articles#index and /articles/:id (GET) -> articles#show -> Option A

4. Quick Check:

   resources with only index, show = GET /articles and GET /articles/:id [OK]

Hint: Only index and show create GET /collection and GET /collection/:id [OK]

Common Mistakes:

• Assuming all RESTful routes are created
• Confusing HTTP verbs for actions
• Mixing up new/edit with index/show

4. Identify the error in this route definition:

get '/profile', controller: 'users', action: 'show'

medium

A. URL should not start with a slash

B. Missing 'to:' keyword before controller#action

C. Should use 'post' instead of 'get'

D. Controller name should be capitalized

Solution

1. Step 1: Check correct syntax for get route with controller and action

   The correct syntax uses to: 'controller#action', not separate keys.

2. Step 2: Identify the missing 'to:' keyword

   The given code misses to: and incorrectly uses separate keys.

3. Final Answer:

   Missing 'to:' keyword before controller#action -> Option B

4. Quick Check:

   Use get '/url', to: 'controller#action' [OK]

Hint: Use 'to:' keyword for controller#action in routes [OK]

Common Mistakes:

• Omitting 'to:' keyword
• Using wrong HTTP verb
• Incorrect URL format

5. You want to create routes for a blog with posts and nested comments. Which route definition correctly creates RESTful routes for posts and nested comments inside routes.rb?

hard

A. resources :posts do
resources :comments
end

B. resources :posts, comments: true

C. resource :posts do
resource :comments
end

D. get '/posts/:post_id/comments', to: 'comments#index' only

Solution

1. Step 1: Understand nested resources syntax

   Nested resources are defined by placing one resources block inside another.

2. Step 2: Identify correct nested syntax for posts and comments

   resources :posts do resources :comments end correctly nests comments inside posts using a block.

3. Final Answer:

   resources :posts do resources :comments end -> Option A

4. Quick Check:

   Nested resources use block syntax [OK]

Hint: Nest resources inside block for nested routes [OK]

Common Mistakes:

• Using singular 'resource' instead of plural 'resources'
• Trying to pass nested resources as options
• Defining only one route manually