java - Spring Web MVC - validate individual request params

Question

I'm running a webapp in Spring Web MVC 3.0 and I have a number of controller methods whose signatures are roughly as follows:

@RequestMapping(value = "/{level1}/{level2}/foo", method = RequestMethod.POST)
public ModelAndView createFoo(@PathVariable long level1,
        @PathVariable long level2,
        @RequestParam("foo_name") String fooname,
        @RequestParam(value = "description", required = false) String description);

I'd like to add some validation - for example, description should be limited to a certain length or fooname should only contain certain characters. If this validation fails, I want to return a message to the user rather than just throw some unchecked exception (which would happen anyway if I let the data percolate down to the DAO layer). I'm aware of JSR303 but have not worked with it and don't quite understand how to apply it in a Spring context.

From what I understand, another option would be to bind the @RequestBody to an entire domain object and add validation constraints there, but currently my code is set up to accept individual parameters as shown above.

What is the most straightforward way to apply validation to input parameters using this approach?

Answer 1

This seems to be possible now (tried with Spring 4.1.2), see https://raymondhlee.wordpress.com/2015/08/29/validating-spring-mvc-request-mapping-method-parameters/

Extract from above page:

1. Add MethodValidationPostProcessor to Spring @Configuration class:

   @Bean
   public MethodValidationPostProcessor methodValidationPostProcessor() {
       return new MethodValidationPostProcessor();
   }
   

2. Add @Validated to controller class

3. Use @Size just before @RequestParam

   @RequestMapping("/hi")
   public String sayHi(@Size(max = 10, message = "name should at most 10 characters long") @RequestParam("name") String name) {
       return "Hi " + name;
   

   }

4. Handle ConstraintViolationException in an @ExceptionHandler method