HTTP methods and CRUD mapping in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the HTTP GET method do in CRUD operations?

GET is used to read or retrieve data from the server without changing it.

beginner

Which HTTP method is used to create new data in CRUD?

POST is used to create new resources or data on the server.

intermediate

How does the HTTP PUT method relate to CRUD?

PUT is used to update existing data by replacing it completely.

intermediate

What is the difference between PUT and PATCH in CRUD?

PUT replaces the entire resource, while PATCH partially updates the resource.

beginner

Which HTTP method is used to delete data in CRUD?

DELETE is used to remove data or resources from the server.

Which HTTP method is typically used to retrieve data without changing it?

A DELETE

B POST

C PUT

D GET

GET requests fetch data without modifying it.

Which HTTP method should you use to create a new resource?

A POST

B PATCH

C GET

D DELETE

POST is used to create new resources on the server.

If you want to update only part of a resource, which HTTP method fits best?

A PATCH

B POST

C PUT

D GET

PATCH updates parts of a resource without replacing it fully.

Which HTTP method removes a resource from the server?

A PUT

B DELETE

C POST

D GET

DELETE removes resources from the server.

What is the main difference between PUT and PATCH?

A PUT creates, PATCH deletes

B PUT reads data, PATCH creates data

C PUT replaces entire resource, PATCH updates part

D PUT deletes data, PATCH reads data

PUT replaces the whole resource; PATCH updates only parts.

Explain how HTTP methods map to CRUD operations with simple examples.

Think about how you interact with data: reading, adding, changing, or deleting.

Describe the difference between PUT and PATCH methods in updating resources.

Consider if you want to change everything or just a piece.

Practice

1. Which HTTP method is typically used to retrieve data from a server in a RESTful API?

easy

A. GET

B. POST

C. PUT

D. DELETE

Solution

1. Step 1: Understand HTTP methods and their purposes

   In RESTful APIs, GET is used to read or retrieve data from the server.

2. Step 2: Match the method to the action

   POST creates, PUT updates, and DELETE removes data, so only GET fits retrieving data.

3. Final Answer:

   GET -> Option A

4. Quick Check:

   Read = GET [OK]

Hint: GET is for reading data, like looking at a book [OK]

Common Mistakes:

• Confusing POST with GET
• Using DELETE to fetch data
• Thinking PUT retrieves data

2. Which of the following Express route definitions correctly handles updating a resource using the HTTP method for update?

easy

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

B. app.post('/item/:id', handler)

C. app.put('/item/:id', handler)

D. app.delete('/item/:id', handler)

Solution

1. Step 1: Identify the HTTP method for updating

   Updating a resource uses the PUT method in RESTful APIs.

2. Step 2: Match Express method to HTTP method

   Express uses app.put() to handle PUT requests, so app.put('/item/:id', handler) is correct.

3. Final Answer:

   app.put('/item/:id', handler) -> Option C

4. Quick Check:

   Update = PUT = app.put() [OK]

Hint: Use app.put() for updates in Express routes [OK]

Common Mistakes:

• Using app.post() for updates
• Using app.get() for updates
• Confusing app.delete() with update

3. Consider this Express code snippet:

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

// Client sends DELETE request to /user/42

What will the server respond with?

medium

A. "Updated user 42"

B. "Deleted user 42"

C. "Created user 42"

D. 404 Not Found

Solution

1. Step 1: Understand the route and HTTP method

   The route listens for DELETE requests on /user/:id. The client sends a DELETE request to /user/42.

2. Step 2: Analyze the response sent

   The handler sends back the string Deleted user 42 using the id from the URL.

3. Final Answer:

   "Deleted user 42" -> Option B

4. Quick Check:

   DELETE request responds with deletion message [OK]

Hint: DELETE routes respond with deletion confirmation [OK]

Common Mistakes:

• Confusing DELETE with POST response
• Expecting 404 instead of success message
• Mixing up URL parameters

4. What is wrong with this Express route for creating a new item?

app.get('/items', (req, res) => {
  // code to add new item
  res.send('Item created');
});

medium

A. Missing route parameter for item ID

B. Route path should be '/item' not '/items'

C. Response message is incorrect

D. GET method should not be used to create data

Solution

1. Step 1: Identify the HTTP method used

   The route uses GET, which is meant for reading data, not creating.

2. Step 2: Match method to CRUD action

   Creating new data should use POST, so using GET here is incorrect.

3. Final Answer:

   GET method should not be used to create data -> Option D

4. Quick Check:

   Create = POST, not GET [OK]

Hint: Use POST to create, not GET [OK]

Common Mistakes:

• Using GET to create resources
• Ignoring HTTP method semantics
• Assuming route path is the issue

5. You want to build an Express API that allows clients to create, read, update, and delete "products". Which set of route definitions correctly maps HTTP methods to CRUD actions?

hard

A. app.post('/products', createHandler); app.get('/products/:id', readHandler); app.put('/products/:id', updateHandler); app.delete('/products/:id', deleteHandler);

B. app.get('/products', createHandler); app.post('/products/:id', readHandler); app.put('/products', updateHandler); app.delete('/products', deleteHandler);

C. app.put('/products', createHandler); app.get('/products/:id', readHandler); app.post('/products/:id', updateHandler); app.delete('/products/:id', deleteHandler);

D. app.delete('/products', createHandler); app.put('/products/:id', readHandler); app.post('/products/:id', updateHandler); app.get('/products/:id', deleteHandler);

Solution

1. Step 1: Match each CRUD action to correct HTTP method

   Create = POST, Read = GET, Update = PUT, Delete = DELETE.

2. Step 2: Check route paths and handlers

   app.post('/products', createHandler); app.get('/products/:id', readHandler); app.put('/products/:id', updateHandler); app.delete('/products/:id', deleteHandler); uses POST /products for create, GET /products/:id for read, PUT /products/:id for update, and DELETE /products/:id for delete, which is correct.

3. Final Answer:

   app.post('/products', createHandler); app.get('/products/:id', readHandler); app.put('/products/:id', updateHandler); app.delete('/products/:id', deleteHandler); -> Option A

4. Quick Check:

   POST=create, GET=read, PUT=update, DELETE=delete [OK]

Hint: Remember CRUD: POST, GET, PUT, DELETE order [OK]

Common Mistakes:

• Mixing POST and GET methods
• Using wrong paths for actions
• Assigning update to POST instead of PUT