@RequestBody Validation

• Used with @Valid or @Validated to validate incoming request body (POJO) before method execution.
• If validation fails, throws a MethodArgumentNotValidException and returns a 400 Bad Request response.

Requirements:

• Add spring-boot-starter-validation dependency (Hibernate Validator).
• Add validation annotations in the model ( @NotNull,@NotEmpty,@Email).
• Use @Valid or @Validated before the @RequestBody parameter.

Example

@PostMapping("/user")
public void createUser(@Valid @RequestBody User user) {}

Model Class :

public class User {
    @NotBlank
    private String name;

    @Email
    private String email;

    @Min(18)
    private int age;
}

In Invalid request:

{
  "name": "",
  "email": "invalid",
  "age": 15
}

Response: 400 Bad Request With error details like:

{
  "errors": [
    "name must not be blank",
    "email must be a valid email address",
    "age must be greater than or equal to 18"
  ]
}

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