RESTful resource routes in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does RESTful resource routing in Rails do?

It automatically creates standard routes for common actions like showing, creating, updating, and deleting resources, following REST principles.

beginner

Name the 7 standard RESTful actions Rails generates for a resource.

index, show, new, create, edit, update, destroy

beginner

What HTTP verb and path does the 'create' action use in RESTful routes?

POST request to /resources (e.g., POST /articles)

beginner

How do you define RESTful routes for a resource named 'books' in Rails?

Use resources :books in the config/routes.rb file.

beginner

What URL and HTTP verb does the 'edit' action use for a resource with id 5?

GET request to /resources/5/edit (e.g., GET /books/5/edit)

Which HTTP verb is used to update a resource in RESTful routes?

A PATCH

B GET

C POST

D DELETE

The PATCH verb is used to update an existing resource partially or fully.

What route helper does Rails generate for the 'show' action of a resource named 'posts'?

A posts_path

B post_path(id)

C new_post_path

D edit_post_path(id)

The 'show' action uses post_path(id) to show a single post.

Which RESTful action corresponds to the URL '/articles/new'?

A index

B show

C new

D edit

The '/articles/new' URL shows the form to create a new article.

What does the 'destroy' action do in RESTful routes?

A Deletes a resource

B Shows a resource

C Creates a resource

D Edits a resource

The 'destroy' action deletes a resource from the database.

How do you limit RESTful routes to only 'index' and 'show' actions in Rails?

A resource :items, only: [:index, :show]

B resources :items, except: [:index, :show]

C resources :items, limit: [:index, :show]

D resources :items, only: [:index, :show]

Use the 'only' option to specify which actions to generate routes for.

Explain how RESTful resource routes in Rails map HTTP verbs and URLs to controller actions.

Think about how Rails uses 'resources' to create these routes automatically.

Describe how you would customize RESTful routes in Rails to only include certain actions.

Look at the options you can pass to 'resources' in routes.rb.

Practice

1. What does the resources :books line do in a Rails routes file?

easy

A. Creates all standard RESTful routes for the books resource automatically.

B. Creates only the index and show routes for books.

C. Creates a single custom route named books.

D. Deletes all routes related to books.

Solution

1. Step 1: Understand the resources method

   The resources method in Rails automatically generates all seven standard RESTful routes (index, show, new, create, edit, update, destroy) for a given resource.

2. Step 2: Apply to resources :books

   Using resources :books creates all these routes for the books controller, enabling standard CRUD actions.

3. Final Answer:

   Creates all standard RESTful routes for the books resource automatically. -> Option A

4. Quick Check:

   resources :books = all RESTful routes [OK]

Hint: Remember: resources creates all standard routes by default [OK]

Common Mistakes:

• Thinking it creates only some routes
• Confusing resources with resource (singular)
• Assuming it deletes routes

2. Which of the following is the correct syntax to create only the index and show routes for a resource named articles?

easy

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

B. resources :articles, except: [:index, :show]

C. resource :articles, only: [:index, :show]

D. resources :articles, only: index, show

Solution

1. Step 1: Use resources with only option

   To limit routes to specific actions, use only: [:index, :show] with resources.

2. Step 2: Check syntax correctness

   resources :articles, only: [:index, :show] correctly uses symbols in an array with only. resources :articles, except: [:index, :show] uses except which excludes actions, not includes. resource :articles, only: [:index, :show] uses singular resource which is for single objects, not collections. resources :articles, only: index, show syntax is invalid because only expects an array.

3. Final Answer:

   resources :articles, only: [:index, :show] -> Option A

4. Quick Check:

   Limit routes with only and array [OK]

Hint: Use only: with an array of symbols to limit routes [OK]

Common Mistakes:

• Using except instead of only
• Using singular resource for collections
• Incorrect syntax without brackets

3. Given the route declaration resources :users, except: [:destroy], which HTTP verb and path will NOT be available?

medium

A. GET /users/:id/edit

B. DELETE /users/:id

C. POST /users

D. GET /users

Solution

1. Step 1: Understand except: [:destroy]

   The except option removes the specified action routes. Here, destroy is excluded, so no route for deleting a user is created.

2. Step 2: Identify the HTTP verb and path for destroy

   The destroy action corresponds to the HTTP DELETE verb on the path /users/:id. This route will be missing.

3. Final Answer:

   DELETE /users/:id -> Option B

4. Quick Check:

   except: [:destroy] removes DELETE route [OK]

Hint: Destroy action uses DELETE verb; except removes it [OK]

Common Mistakes:

• Confusing except with only
• Thinking GET routes are removed
• Mixing HTTP verbs with wrong actions

4. Identify the error in this routes file snippet:

resources :products, only: :show, :edit

medium

A. The only option should list all seven RESTful actions.

B. The resources method cannot use only option.

C. The resource name products should be singular.

D. The only option should be an array of symbols, not separate symbols.

Solution

1. Step 1: Check syntax of only option

   The only option expects an array of symbols like only: [:show, :edit]. Writing only: :show, :edit passes :show as the only option and :edit is outside the hash, causing syntax error.

2. Step 2: Verify other options

   resources supports only. The resource name should be plural for collections. Listing all actions is optional.

3. Final Answer:

   The only option should be an array of symbols, not separate symbols. -> Option D

4. Quick Check:

   only needs array syntax [OK]

Hint: Use brackets for multiple actions in only: [:show, :edit] [OK]

Common Mistakes:

• Omitting brackets for multiple actions
• Using singular resource for collections
• Thinking only must list all actions

5. You want to create RESTful routes for a resource orders but only allow index, show, and create actions. Additionally, you want a custom member route cancel that responds to POST requests. Which routes file code is correct?

hard

A. resources :orders, except: [:edit, :update, :destroy] do\n post 'cancel', on: :member\nend

B. resources :orders, only: [:index, :show, :create] do\n get 'cancel', on: :collection\nend

C. resources :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend

D. resource :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend

Solution

1. Step 1: Limit routes to index, show, create

   Use only: [:index, :show, :create] to restrict routes to these actions.

2. Step 2: Add custom member route for cancel

   Use a block with post 'cancel', on: :member to add a POST route for cancel on individual orders.

3. Step 3: Check other options

   resources :orders, only: [:index, :show, :create] do\n get 'cancel', on: :collection\nend uses GET and collection which is incorrect for cancel on a single order. resources :orders, except: [:edit, :update, :destroy] do\n post 'cancel', on: :member\nend uses except which is less clear and includes extra routes. resource :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend uses singular resource which is wrong for collections.

4. Final Answer:

   resources :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend -> Option C

5. Quick Check:

   Use only with member block for custom POST route [OK]

Hint: Use member block with post for single resource custom action [OK]

Common Mistakes:

• Using collection instead of member for single resource
• Using singular resource for collections
• Using wrong HTTP verb for custom action