[Solved] Consider this controller method:@PostMapping("/user") public String createUser(@RequestBody User user) { return user.getEmail(); }If the client sends an empty request body, what will happen? | Spring Boot

Spring Boot - REST Controllers

Consider this controller method:

@PostMapping("/user")
public String createUser(@RequestBody User user) {
  return user.getEmail();
}

If the client sends an empty request body, what will happen?

ASpring Boot throws an HTTP 400 Bad Request error

BThe method returns null

CThe method returns an empty string

DCompilation error due to missing @RequestBody

Step-by-Step Solution

Solution:

Step 1: Check behavior with empty JSON body
When @RequestBody expects JSON but receives empty body, Spring Boot cannot create the User object.
Step 2: Understand Spring Boot error handling
Spring Boot responds with HTTP 400 Bad Request for missing or malformed JSON input.
Final Answer:
Spring Boot throws an HTTP 400 Bad Request error -> Option A
Quick Check:
Empty JSON body causes HTTP 400 error [OK]

Quick Trick: Empty JSON body with @RequestBody causes HTTP 400 error [OK]

Common Mistakes:

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