[Solved] Which of the following method signatures correctly defines a POST endpoint in Spring Boot that accepts a JSON payload mapped to a Java object User? | Spring Boot

Spring Boot - REST Controllers

Which of the following method signatures correctly defines a POST endpoint in Spring Boot that accepts a JSON payload mapped to a Java object User?

A

@PostMapping("/createUser")
public ResponseEntity<String> createUser(@RequestBody User user) { ... }

B

@PostMapping("/createUser")
public ResponseEntity<String> createUser(User user) { ... }

C

@GetMapping("/createUser")
public ResponseEntity<String> createUser(@RequestBody User user) { ... }

D

@PostMapping("/createUser")
public ResponseEntity<String> createUser(@RequestParam User user) { ... }

Step-by-Step Solution

Solution:

Step 1: Identify correct HTTP method annotation
Use @PostMapping for POST endpoints.
Step 2: Correctly bind JSON payload
Use @RequestBody to map JSON request body to Java object.
Step 3: Analyze options
@PostMapping("/createUser") public ResponseEntity createUser(@RequestBody User user) { ... } uses @PostMapping and @RequestBody correctly. @PostMapping("/createUser") public ResponseEntity createUser(User user) { ... } misses @RequestBody, so JSON won't bind properly. @GetMapping("/createUser") public ResponseEntity createUser(@RequestBody User user) { ... } uses @GetMapping, which is incorrect. @PostMapping("/createUser") public ResponseEntity createUser(@RequestParam User user) { ... } uses @RequestParam, which binds query parameters, not JSON body.
Final Answer:
Option A -> Option A
Quick Check:
POST + @RequestBody for JSON binding [OK]

Quick Trick: Use @PostMapping with @RequestBody for JSON input [OK]

Common Mistakes:

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Which of the following method signatures correctly defines a POST endpoint in Spring Boot that accepts a JSON payload mapped to a Java object User?