Adding multiple validators using initBinder

Question

I'm adding a user validator using the `initBinder` method: ``` @InitBinder protected void initBinder(WebDataBinder binder) { binder.setValidator(new UserValidator()); } ``` Here is the `UserValidator` ``` public class UserValidator implements Validator { public boolean supports(Class clazz) { return User.class.equals(clazz); } public void validate(Object target, Errors errors) { User u = (User) target; // more code here } } ``` The `validate` method is getting properly called during the controller method call. ``` @RequestMapping(value = "/makePayment", method = RequestMethod.POST) public String saveUserInformation(@Valid User user, BindingResult result, Model model){ // saving User here // Preparing CustomerPayment object for the payment page. CustomerPayment customerPayment = new CustomerPayment(); customerPayment.setPackageTb(packageTb); model.addAttribute(customerPayment); logger.debug("Redirecting to Payment page."); return "registration/payment"; } ``` But while returning to the…

Accepted Answer

You need to set the value of the `@InitBinder` annotation to the name of the command you want it to validate. This tells Spring what to apply the binder to; without it, Spring will try to apply it to everything. This is why you're seeing that exception: Spring is trying to apply the binder - with your `UserValidator` - to a parameter of type `CustomerPayment`.

In your specific case, it looks like you need something like:

```
@InitBinder("user")
protected void initBinder(WebDataBinder binder) {
    binder.setValidator(new UserValidator());
}
```

To your second question, as Rigg802 explained, Spring does not support attaching multiple validators to a single command. You can, however, define multiple `@InitBinder` methods for different commands. So, for example, you could put the following in a single controller and validate your user and payment parameters:

```
@InitBinder("user")
protected void initUserBinder(WebDataBinder binder) {
    binder.setValidator(new UserValidator());
}

@InitBinder("customerPayment")
protected void initPaymentBinder(WebDataBinder binder) {
    binder.setValidator(new CustomerPaymentValidator());
}
```

Adding multiple validators using initBinder

Solution

Problem