RESTful resource routes in Ruby on Rails - Step-by-Step Execution

Concept Flow - RESTful resource routes

Client sends HTTP request

↓

Rails router matches URL + HTTP verb

↓

Select controller and action

↓

Controller processes request

↓

Render view or redirect

↓

Send HTTP response back to client

Rails uses the URL and HTTP method to pick the right controller action, which then handles the request and sends back a response.

Execution Sample

Ruby on Rails

resources :books

# GET /books -> books#index
# POST /books -> books#create
# GET /books/:id -> books#show
# PATCH /books/:id -> books#update
# DELETE /books/:id -> books#destroy

Defines standard RESTful routes for a 'books' resource, mapping HTTP verbs and URLs to controller actions.

Execution Table

Step	HTTP Verb	URL	Controller#Action	Purpose
1	GET	/books	books#index	Show list of all books
2	GET	/books/new	books#new	Show form to create a new book
3	POST	/books	books#create	Create a new book
4	GET	/books/:id	books#show	Show details of one book
5	GET	/books/:id/edit	books#edit	Show form to edit a book
6	PATCH	/books/:id	books#update	Update a book
7	PUT	/books/:id	books#update	Update a book (alternative)
8	DELETE	/books/:id	books#destroy	Delete a book
9	-	-	-	No more routes, routing ends

💡 All standard RESTful routes for 'books' resource are matched and handled.

Variable Tracker

Variable	Start	After Step 1	After Step 3	After Step 6	Final
params[:id]	nil	nil	nil	42	42
request.method	nil	GET	POST	PATCH	PATCH
controller_action	nil	books#index	books#create	books#update	books#update

Key Moments - 3 Insights

Why does the same URL /books/:id respond to different actions?

Because Rails uses the HTTP verb (GET, PATCH, DELETE) along with the URL to decide which controller action to run, as shown in execution_table rows 4, 6, and 8.

What happens if I send a POST request to /books/:id?

There is no route for POST with /books/:id, so Rails will return a routing error. Only POST /books (row 3) is valid for creating.

Why are there both PATCH and PUT routes for update?

Rails supports both PATCH and PUT for updating resources (rows 6 and 7), but PATCH is preferred for partial updates.

Visual Quiz - 3 Questions

Look at the execution_table, which controller action handles GET /books/5/edit?

A books#show

B books#edit

C books#update

D books#new

💡 Hint

Check row 5 in the execution_table for GET /books/:id/edit

At which step does the controller action books#create get called?

A Step 2

B Step 4

C Step 3

D Step 6

💡 Hint

Look for POST /books in the execution_table

If you send a DELETE request to /books/10, which action runs and what is params[:id]?

A books#destroy, params[:id] = 10

B books#show, params[:id] = 10

C books#destroy, params[:id] = nil

D Routing error

💡 Hint

See row 8 in execution_table and variable_tracker for params[:id]

Concept Snapshot

RESTful resource routes in Rails map HTTP verbs and URLs to controller actions.
Use 'resources :name' to create 7 standard routes.
GET for reading, POST for creating, PATCH/PUT for updating, DELETE for deleting.
URLs include optional :id for single resource actions.
Rails router matches verb + URL to pick controller#action.
This keeps routes organized and predictable.

Full Transcript

In Rails, RESTful resource routes connect HTTP methods and URLs to specific controller actions. When a client sends a request, Rails looks at the URL and the HTTP verb to find the matching route. For example, GET /books calls the books#index action to list all books. POST /books calls books#create to add a new book. URLs with an :id like /books/42 target a single book for showing, editing, updating, or deleting. PATCH and PUT both update a book, but PATCH is preferred for partial updates. This system helps keep your app's routes clear and easy to understand.

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