Resource-based URL design in Express

Introduction

Resource-based URL design helps organize web addresses so they clearly show what data or action they relate to. It makes websites easier to understand and use.

When building a web API to manage users, products, or orders.

When you want URLs that are easy to read and remember.

When designing routes that follow REST principles for clarity.

When you want to separate different data types with clear paths.

When you want to make your app easier to maintain and extend.

Syntax

Express

app.METHOD('/resource/:id', handlerFunction)

METHOD is the HTTP method like GET, POST, PUT, DELETE.

Use :id to capture a specific resource identifier from the URL.

Examples

Get a list of all users.

Express

app.get('/users', (req, res) => { /* list users */ })

Get details of a single user by their ID.

Express

app.get('/users/:id', (req, res) => { /* get user by id */ })

Create a new user resource.

Express

app.post('/users', (req, res) => { /* create new user */ })

Update an existing user by ID.

Express

app.put('/users/:id', (req, res) => { /* update user by id */ })

Sample Program

This Express app uses resource-based URLs for books. You can get all books or a single book by its ID using clear, simple URLs.

Express

import express from 'express';
const app = express();
app.use(express.json());

// List all books
app.get('/books', (req, res) => {
  res.json([{ id: 1, title: 'Book One' }, { id: 2, title: 'Book Two' }]);
});

// Get a book by ID
app.get('/books/:id', (req, res) => {
  const bookId = Number(req.params.id);
  const books = [{ id: 1, title: 'Book One' }, { id: 2, title: 'Book Two' }];
  const book = books.find(b => b.id === bookId);
  if (book) {
    res.json(book);
  } else {
    res.status(404).send('Book not found');
  }
});

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Important Notes

Use plural nouns for resource names (e.g., /books, /users) to keep URLs consistent.

Keep URLs simple and predictable to help users and developers understand them easily.

Use HTTP methods (GET, POST, PUT, DELETE) to represent actions on resources clearly.

Summary

Resource-based URLs organize web addresses around data items like users or books.

They use clear paths and HTTP methods to show what action happens.

This design makes APIs easier to use and maintain.

Practice

1. What is the main idea behind resource-based URL design in Express?

easy

A. Combine all actions into one URL

B. Use random URLs for each action

C. Avoid using HTTP methods in URLs

D. Organize URLs around data items like users or books

Solution

1. Step 1: Understand resource-based URL design

   This design organizes URLs by resources such as users or books, making them clear and meaningful.

2. Step 2: Compare options

   Options B, C, and D do not follow this clear organization principle.

3. Final Answer:

   Organize URLs around data items like users or books -> Option D

4. Quick Check:

   Resource-based URLs = Organize by data items [OK]

Hint: Think: URLs should name data items clearly [OK]

Common Mistakes:

• Thinking URLs should be random or unclear
• Ignoring HTTP methods in design
• Putting all actions under one URL

2. Which Express route correctly follows resource-based URL design to get a user by ID?

easy

A. app.get('/user/:id', handler)

B. app.get('/getUser', handler)

C. app.post('/user/:id', handler)

D. app.delete('/user', handler)

Solution

1. Step 1: Identify correct HTTP method and URL pattern

   To get a user by ID, use GET method and URL with resource and ID: '/user/:id'.

2. Step 2: Check options

   app.get('/user/:id', handler) uses GET and '/user/:id' which is correct. Others use wrong methods or URLs.

3. Final Answer:

   app.get('/user/:id', handler) -> Option A

4. Quick Check:

   GET + /resource/:id = correct get route [OK]

Hint: GET method + resource path with :id for fetching [OK]

Common Mistakes:

• Using POST instead of GET for fetching
• Using generic paths like '/getUser'
• Missing :id parameter in URL

3. What will be the response if the following Express route is called with DELETE /books/123?

app.delete('/books/:bookId', (req, res) => {
  res.send(`Deleted book ${req.params.bookId}`);
});

medium

A. 404 Not Found error

B. "Deleted book :bookId"

C. "Deleted book 123"

D. SyntaxError

Solution

1. Step 1: Understand route and HTTP method

   The route listens for DELETE requests on '/books/:bookId'. The parameter bookId will be '123' from the URL.

2. Step 2: Check response behavior

   The handler sends a string with the bookId inserted, so response is 'Deleted book 123'.

3. Final Answer:

   "Deleted book 123" -> Option C

4. Quick Check:

   DELETE /books/:id returns message with id [OK]

Hint: Route param replaces :bookId in response [OK]

Common Mistakes:

• Confusing parameter name with literal string
• Expecting 404 if route exists
• Thinking syntax error occurs

4. Identify the error in this Express route for updating a user:

app.put('/users', (req, res) => {
  const id = req.params.id;
  res.send(`Updated user ${id}`);
});

medium

A. req.params.id should be req.body.id

B. Missing :id parameter in URL path

C. res.send should be res.json

D. Using PUT instead of POST

Solution

1. Step 1: Check URL path and parameter usage

   The route URL is '/users' but code tries to read req.params.id which requires ':id' in path.

2. Step 2: Identify mismatch

   Since ':id' is missing in URL, req.params.id will be undefined causing error or wrong behavior.

3. Final Answer:

   Missing :id parameter in URL path -> Option B

4. Quick Check:

   URL must include :id to access req.params.id [OK]

Hint: Check if URL path matches params used in code [OK]

Common Mistakes:

• Ignoring missing :id in URL
• Confusing req.params with req.body
• Thinking PUT is wrong method here

5. You want to design Express routes for a blog API with posts and comments. Which URL design best follows resource-based principles for updating a comment with ID 45 on post with ID 10?

hard

A. app.put('/posts/10/comments/45', handler)

B. app.put('/updateComment', handler)

C. app.put('/comments/45', handler)

D. app.put('/posts/comments', handler)

Solution

1. Step 1: Understand nested resource URLs

   Comments belong to posts, so URL should reflect this hierarchy: '/posts/:postId/comments/:commentId'.

2. Step 2: Check options for correct pattern

   app.put('/posts/10/comments/45', handler) uses full nested path with IDs, matching resource-based design. Others miss nesting or IDs.

3. Final Answer:

   app.put('/posts/10/comments/45', handler) -> Option A

4. Quick Check:

   Nested resource URLs = /posts/:postId/comments/:commentId [OK]

Hint: Nest related resources in URL with IDs [OK]

Common Mistakes:

• Using generic action names in URL
• Omitting parent resource ID
• Ignoring resource hierarchy