Seam and Hibernate validation

[kirkor.grzegorz.bernas.com.pl]

I have situation when I want to check is the string passed from form have exactly 26 digits. So in my entity beam I add @Length(max = 26, min = 26).
I use ajax validation and if I enter 1 digit validation error is shown. But when I remove him and try to save my form I get error: org.hibernate.validator.InvalidStateException with messages: invalidValues [bankAccount length must be between 26 and 26].
My question is:
1. why seam doesn't shows this message in ajax validation?
2. how to made validation that accept string with 0 length, but if is more then 0 then expect exactly 26 digits?

[binnyg]

How about a custom validator?
Look for Marcus Popetz's response here

[norad2]

You could use a regex validator

@Pattern(regex = "^$|^\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d\d$")

[binnyg]

or a regular expression as Dan mentioned. You can make the rule more readable like this

@Pattern(regex = "^$|^\d{26}$")

[joblini]

Post your code, especially the a4j:support.  You need to use the onblur event so that validation is performed only when you move out of the field.