JSR - 349 bean validation for Spring @RestController with Spring Boot

Sabir Khan :

I am using Spring Boot 1.5.2.RELEASE and not able to incorporate JSR - 349 ( bean validation 1.1 ) for @RequestParam & @PathVariable at method itself.

For POST requests, if method parameter is a Java POJO then annotating that parameter with @Valid is working fine but annotating @RequestParam & @PathVariable with something like @NotEmpty, @Email not working.

I have annotated controller class with Spring's @Validated

There are lots of questions on SO and I have commented on this answer that its not working for me.

Spring Boot includes - validation-api-1.1.0.Final.jar and hibernate-validator-5.3.4.Final.jar .

Am I missing anything?

Example code ,

@RequestMapping(method = RequestMethod.GET, value = "/testValidated", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseBean<String> testValidated(@Email @NotEmpty @RequestParam("email") String email) {
    ResponseBean<String> response = new ResponseBean<>();
    response.setResponse(Constants.SUCCESS);
    response.setMessage("testValidated");
    logger.error("Validator Not called");
    return response; 
}

Below handler is never called when I send empty values or not well formed email address for email & control always goes to with in testValidated method.

@ExceptionHandler(ConstraintViolationException.class)
@ResponseBody
@ResponseStatus(HttpStatus.BAD_REQUEST)
public ResponseBean handle(ConstraintViolationException exception) {

    StringBuilder messages = new StringBuilder();
    ResponseBean response = new ResponseBean();

    exception.getConstraintViolations().forEach(entry -> messages.append(entry.getMessage() + "\n"));

    response.setResponse(Constants.FAILURE);
    response.setErrorcode(Constants.ERROR_CODE_BAD_REQUEST);
    response.setMessage(messages.toString());
    return response;
}

ResponseBean<T> is my application specific class.

Sabir Khan :

I had asked the question after more than two days of unsuccessful hit & trial. Lots of confusing answers are out there because of confusions around Spring Validations and JSR validations, how Spring invokes JSR validators, changes in JSR standards & types of validations supported.

Finally, this article helped a lot.

I solved problem in two steps,

1.Added following beans to my Configuration - without these beans , nothing works.

@Bean
public MethodValidationPostProcessor methodValidationPostProcessor() {
    MethodValidationPostProcessor mvProcessor = new MethodValidationPostProcessor();
    mvProcessor.setValidator(validator());
    return mvProcessor;
}           

@Bean
public LocalValidatorFactoryBean validator() {
    LocalValidatorFactoryBean validator = new LocalValidatorFactoryBean();
    validator.setProviderClass(HibernateValidator.class);
    validator.afterPropertiesSet();
    return validator;
}

2.Placed Spring's @Validated annotation on my controller like below,

@RestController
@RequestMapping("/...")
@Validated
public class MyRestController {
}

Validated is - org.springframework.validation.annotation.Validated

This set up doesn't affected @Valid annotations for @RequestBody validations in same controller and those continued to work as those were.

So now, I can trigger validations like below for methods in MyRestController class,

@RequestMapping(method = RequestMethod.GET, value = "/testValidated" , consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseBean<String> testValidated(
        @Email(message="email RequestParam is not a valid email address") 
        @NotEmpty(message="email RequestParam is empty") 
        @RequestParam("email") String email) {
    ResponseBean<String> response = new ResponseBean<>();
    ....
    return response; 
}

I had to add another handler in exception handler for exception - ConstraintViolationException though since @Validated throws this exception while @Valid throws MethodArgumentNotValidException