<form:errors> and nested exceptions

Is there a way to replace nested exceptions in an Errors or BindingResult object with a localized "friendly" error message?

Some info:

I do some validation in one of my domain objects to ensure that usernames don't have any fewer than 6 characters by throwing an IllegalArgumentException in the setUserName() method. I'm aware of the Validator interface, which I use for other of my domain objects but it wasn't appropriate in this case.

On the web side of things, when a new user is created with a username fewer than 6 characters, the following appears in my <form:errors />

Code:

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Property username threw exception; nested exception is java.lang.IllegalArgumentException: A username must contain at least six characters.

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While I'm happy that the exception is associated with the appropriate field and included in the Errors object, this isn't very helpful for an end user. Is there a way to "trap" this error and replace it with a friendlier, localized error?

I found the solution, thanks to this extremely helpful post:

http://forum.springframework.org/showthread.php?t=57281

I'm not sure why this isn't in the manual, but any of the "Codes" in an ErrorObject (which can be retrieved using getCodes() ) can be placed in errors.properties to override the unfriendly error messages with localized friendly versions.

In my case, this worked out to:

methodInvocation.user.userName=A username must contain at least six characters.

Easy as pie! At least, once you know how.