Validation

See equivalent in the Reactive stack

Spring MVC has built-in Validation support for @RequestMapping methods, including the option to use Java Bean Validation. The validation support works on two levels.

First, resolvers for @ModelAttribute, @RequestBody, and @RequestPart method parameters perform validation if the parameter has Jakarta’s @Valid or Spring’s @Validated annotation, and raise MethodArgumentNotValidException if necessary. Alternatively, you can handle the errors in the controller method by adding an Errors or BindingResult method parameter immediately after the validated one.

Second, if Java Bean Validation is present AND any method parameter has @Constraint annotations, then method validation is applied instead, raising HandlerMethodValidationException if necessary. For this case you can still add an Errors or BindingResult method parameter to handle validation errors within the controller method, but if other method arguments have validation errors then HandlerMethodValidationException is raised instead. Method validation can apply to the return value if the method is annotated with @Valid or with @Constraint annotations.

You can configure a Validator globally through the WebMvc config, or locally through an @InitBinder method in an @Controller or @ControllerAdvice. You can also use multiple validators.

If a controller has a class level @Validated, then method validation is applied through an AOP proxy. In order to take advantage of the Spring MVC built-in support for method validation added in Spring Framework 6.1, you need to remove the class level @Validated annotation from the controller.

The Error Responses section provides further details on how MethodArgumentNotValidException and HandlerMethodValidationException are handled, and also how their rendering can be customized through a MessageSource and locale and language specific resource bundles.

For further custom handling of method validation errors, you can extend ResponseEntityExceptionHandler or use an @ExceptionHandler method in a controller or in a @ControllerAdvice, and handle HandlerMethodValidationException directly. The exception contains a list ofParameterValidationResults that group validation errors by method parameter. You can either iterate over those, or provide a visitor with callback methods by controller method parameter type:

Java
Kotlin

HandlerMethodValidationException ex = ... ;

ex.visitResults(new HandlerMethodValidationException.Visitor() {

	@Override
	public void requestHeader(RequestHeader requestHeader, ParameterValidationResult result) {
			// ...
	}

	@Override
	public void requestParam(@Nullable RequestParam requestParam, ParameterValidationResult result) {
			// ...
	}

	@Override
	public void modelAttribute(@Nullable ModelAttribute modelAttribute, ParameterErrors errors) {

	// ...

	@Override
	public void other(ParameterValidationResult result) {
			// ...
	}
});

// HandlerMethodValidationException
val ex

ex.visitResults(object : HandlerMethodValidationException.Visitor {

	override fun requestHeader(requestHeader: RequestHeader, result: ParameterValidationResult) {
			// ...
       }

	override fun requestParam(requestParam: RequestParam?, result: ParameterValidationResult) {
			// ...
       }

	override fun modelAttribute(modelAttribute: ModelAttribute?, errors: ParameterErrors) {
			// ...
       }

	// ...

	override fun other(result: ParameterValidationResult) {
			// ...
       }
})