Why @PutMapping and @DeleteMapping in Spring Boot? - Purpose & Use Cases

The Big Idea

Discover how a few simple annotations can save you hours of messy code and bugs!

The Scenario

Imagine building a web app where you have to update or delete user data by manually parsing HTTP requests and writing complex code to handle each action.

The Problem

Manually handling HTTP PUT and DELETE requests is error-prone, repetitive, and makes your code messy and hard to maintain.

The Solution

@PutMapping and @DeleteMapping annotations in Spring Boot let you easily link HTTP PUT and DELETE requests to specific methods, making your code clean and clear.

Before vs After

✗ Before

if(request.getMethod().equals("PUT")) { updateUser(); } else if(request.getMethod().equals("DELETE")) { deleteUser(); }

✓ After

@PutMapping("/user")
public void updateUser() { ... }
@DeleteMapping("/user")
public void deleteUser() { ... }

What It Enables

This makes your web app respond correctly to update and delete actions with minimal code and clear structure.

Real Life Example

When a user edits their profile or removes their account, @PutMapping and @DeleteMapping handle these requests smoothly behind the scenes.

Key Takeaways

Manually handling HTTP methods is complex and error-prone.

@PutMapping and @DeleteMapping simplify routing for update and delete actions.

They make your code cleaner, easier to read, and maintain.

Practice

1. What is the primary purpose of the @PutMapping annotation in Spring Boot?

easy

A. To handle HTTP GET requests for retrieving data

B. To handle HTTP PUT requests for updating existing resources

C. To handle HTTP POST requests for creating new resources

D. To handle HTTP DELETE requests for removing resources

Solution

1. Step 1: Understand HTTP methods

   HTTP PUT is used to update existing data on the server.

2. Step 2: Match annotation to HTTP method

   @PutMapping maps HTTP PUT requests to controller methods.

3. Final Answer:

   To handle HTTP PUT requests for updating existing resources -> Option B

4. Quick Check:

   @PutMapping = update data [OK]

Hint: Put means update existing data via HTTP PUT [OK]

Common Mistakes:

• Confusing @PutMapping with @PostMapping
• Thinking @PutMapping creates new data
• Mixing HTTP methods like GET or DELETE

2. Which of the following is the correct syntax to define a method that deletes a resource by ID using @DeleteMapping?

easy

A. @DeleteMapping("/items/{id}") public void deleteItem(int id) {}

B. @DeleteMapping("/items") public void deleteItem(int id) {}

C. @DeleteMapping("/items/{id}") public void deleteItem(@PathVariable int id) {}

D. @DeleteMapping("/items") public void deleteItem(@RequestParam int id) {}

Solution

1. Step 1: Identify correct URL pattern and annotation

   To delete by ID, URL should include path variable like /items/{id} and method parameter annotated with @PathVariable.

2. Step 2: Check method signature matches path variable

   @DeleteMapping("/items/{id}") public void deleteItem(@PathVariable int id) {} correctly uses @DeleteMapping with path and @PathVariable int id parameter.

3. Final Answer:

   @DeleteMapping("/items/{id}") public void deleteItem(@PathVariable int id) {} -> Option C

4. Quick Check:

   Delete by ID needs @PathVariable and matching URL [OK]

Hint: Use @PathVariable with URL {id} in @DeleteMapping [OK]

Common Mistakes:

• Omitting @PathVariable annotation
• Using @RequestParam instead of @PathVariable for path params
• Not matching method parameter to URL placeholder

3. Given the following Spring Boot controller method, what will happen when a PUT request is sent to /users/5 with a valid JSON body?

@PutMapping("/users/{id}")
public User updateUser(@PathVariable int id, @RequestBody User user) {
    user.setId(id);
    return userService.save(user);
}

medium

A. The user with ID 5 will be updated with the JSON data and returned

B. A new user will be created ignoring the ID in the URL

C. The request will fail because @RequestBody is missing

D. The user ID will not be set and cause an error

Solution

1. Step 1: Analyze method parameters and annotations

   The method uses @PutMapping with path variable id and @RequestBody user object. It sets user ID from path.

2. Step 2: Understand method behavior on PUT request

   It updates the user ID to match URL, then calls save to update and returns updated user.

3. Final Answer:

   The user with ID 5 will be updated with the JSON data and returned -> Option A

4. Quick Check:

   PUT updates resource with URL ID and JSON body [OK]

Hint: PUT with @RequestBody updates resource using URL ID [OK]

Common Mistakes:

• Assuming PUT creates new resource instead of updating
• Ignoring @PathVariable ID and using JSON ID only
• Missing @RequestBody causing request failure

4. Identify the error in this Spring Boot controller method intended to delete a user by ID:

@DeleteMapping("/users")
public void deleteUser(@PathVariable int id) {
    userService.deleteById(id);
}

medium

A. The URL does not include the path variable placeholder {id}

B. The method should use @RequestParam instead of @PathVariable

C. The method should return a value instead of void

D. The @DeleteMapping annotation is missing

Solution

1. Step 1: Check URL and method parameters

   The method expects @PathVariable int id but URL is "/users" without {id} placeholder.

2. Step 2: Understand path variable binding

   Without {id} in URL, Spring cannot bind path variable, causing error.

3. Final Answer:

   The URL does not include the path variable placeholder {id} -> Option A

4. Quick Check:

   Path variable needs matching {id} in URL [OK]

Hint: Match @PathVariable with {id} in URL path [OK]

Common Mistakes:

• Forgetting to add {id} in URL path
• Using @PathVariable without URL placeholder
• Confusing @RequestParam with @PathVariable

5. You want to implement a REST API in Spring Boot that updates a product's price only if the product exists, otherwise returns 404. Which combination of annotations and code best achieves this using @PutMapping?

hard

A. @PutMapping("/products/{id}") public Product updatePrice(@RequestParam int id, @RequestBody Product p) {
p.setId(id);
return productService.save(p);
}

B. @PutMapping("/products") public Product updatePrice(@RequestBody Product p) {
productService.save(p);
return p;
}

C. @PutMapping("/products/{id}") public void updatePrice(@PathVariable int id, @RequestBody Product p) {
productService.save(p);
}

D. @PutMapping("/products/{id}") public ResponseEntity<Product> updatePrice(@PathVariable int id, @RequestBody Product p) {
return productService.findById(id)
.map(existing -> {
existing.setPrice(p.getPrice());
productService.save(existing);
return ResponseEntity.ok(existing);
})
.orElse(ResponseEntity.notFound().build());
}

Solution

1. Step 1: Check for product existence before update

   @PutMapping("/products/{id}") public ResponseEntity<Product> updatePrice(@PathVariable int id, @RequestBody Product p) { return productService.findById(id) .map(existing -> { existing.setPrice(p.getPrice()); productService.save(existing); return ResponseEntity.ok(existing); }) .orElse(ResponseEntity.notFound().build()); } uses productService.findById(id) to check if product exists, returning 404 if not.

2. Step 2: Update price only if product found and return proper HTTP response

   The map lambda updates the price on the existing product, saves it, and returns ResponseEntity.ok(existing); orElse returns notFound().

3. Final Answer:

   @PutMapping("/products/{id}") public ResponseEntity<Product> updatePrice(@PathVariable int id, @RequestBody Product p) { return productService.findById(id) .map(existing -> { existing.setPrice(p.getPrice()); productService.save(existing); return ResponseEntity.ok(existing); }) .orElse(ResponseEntity.notFound().build()); } -> Option D

4. Quick Check:

   Check existence, update, return 404 if missing [OK]

Hint: Check existence first, then update and return ResponseEntity [OK]

Common Mistakes:

• Not checking if product exists before update
• Using @RequestParam instead of @PathVariable for ID
• Not returning 404 when product missing