Question

I am learning myself Spring MVC 2.5 mostly from the docs. Can someone explain the following:

• Advantages/differences of using command objects versus using @ModelAttribute to pass in the object.
• Is there an easier way to do validation other then writing a Validator object?

Also, in this code how does the line ValidationUtils.rejectIfEmpty(e, "name", "name.empty"); work? How can it check if the name is empty on the person object when the person object is not passed in?

   public void validate(Object obj, Errors e) {
        ValidationUtils.rejectIfEmpty(e, "name", "name.empty");
        Person p = (Person) obj;
        if (p.getAge() < 0) {
            e.rejectValue("age", "negativevalue");
        } else if (p.getAge() > 110) {
            e.rejectValue("age", "too.darn.old");
        }
    }

(this code is from section 5.2 from the docs)

Thanks

Answer 1

Here is the answer of your first question.
http://chompingatbits.com/2009/08/25/spring-formtag-commandname-vs-modelattribute/

according to my experience there isn’t easier way to fullfill validation, because it’s easy enough. You can get it easier integrating libraries such as commons-validator into your project and use pre-defined validation rules in your forms.

http://numberformat.wordpress.com/tag/spring-mvc-validation/

and also with 3rd version of Spring you can use Bean validation using annotations.