Spring Boot Validation and Error Handling 3

Question 1

How do you implement cross-field validation (e.g., confirming a password matches) using Bean Validation?

Accepted Answer

Both A and B are valid approaches

Answer

Use @ScriptAssert on the class and write a script comparing the fields

Answer

Create a class-level constraint annotation and implement a ConstraintValidator for the whole object

Answer

Annotate one field with @MatchField(other="fieldName")

Question 2

What is required to enable Bean Validation on Spring service-layer methods (not controllers)?

Accepted Answer

Annotate the service class with @Validated and ensure spring-boot-starter-validation is on the classpath

Answer

Add @EnableValidation to the main application class

Answer

Inject a Validator bean and call validator.validate() manually in each method

Answer

Use @Valid on the service bean definition in the configuration class

Question 3

What does cascaded validation (@Valid on a nested field) do in Bean Validation?

Accepted Answer

It triggers constraint validation recursively on the nested object's fields

Answer

It validates only the top-level object and ignores nested objects

Answer

It causes Spring to fetch the nested object from the database before validating

Answer

It enables @NotNull checking on the nested reference itself

Question 4

When implementing @AssertTrue for custom field-level validation in a POJO, where should the annotated method be declared?

Accepted Answer

As a getter (isXxx / getXxx) inside the same class being validated

Answer

In a separate ConstraintValidator class registered as a Spring bean

Answer

In a @ControllerAdvice class as a static utility method

Answer

In the repository layer to validate before persistence

Question 5

Which Spring Boot auto-configuration class is responsible for setting up the default error handling endpoint at /error?

Accepted Answer

ErrorMvcAutoConfiguration

Answer

BasicErrorController

Answer

DefaultExceptionHandlerAutoConfiguration

Answer

ServerErrorAutoConfiguration

Question 6

How can you suppress the stack trace from appearing in Spring Boot's /error JSON response in production?

Accepted Answer

Set server.error.include-stacktrace=never in application.properties

Answer

Remove the spring-boot-devtools dependency

Answer

Set logging.level.root=OFF in application.properties

Answer

Add @SuppressStackTrace to the main application class

Question 7

When should you use @ExceptionHandler inside a @Controller versus inside a @ControllerAdvice?

Accepted Answer

@ExceptionHandler in @Controller handles exceptions only for that controller; @ControllerAdvice applies globally

Answer

@ExceptionHandler in @Controller applies globally; @ControllerAdvice applies only to REST controllers

Answer

There is no functional difference between the two placements

Answer

@ExceptionHandler in @ControllerAdvice only handles exceptions thrown in service beans