Firesphere/NetefxValidator — comment on commit b4ab07c706fd7eac85c72ca5e613e0bf082a5caa
File:  line 0
By Zauberfisch:

hi sphere,

I appreciate your contribution, but

setJavascriptValidationHandler is already implemented in the class "Validator" https://github.com/Zauberfisch/sapphire/blob/assetadmin-upload/forms/Validator.php#L76
NetefxValidator.php extends Validator and therefore already has this method

In the paste http://sspaste.com/paste/show/4f202fc592bd0 you used NetefxValidatorRuleFUNCTION, and returned it.
but NetefxValidatorRuleFUNCTION is a rule, not a Validator, you need to put the rule into a validator like this:

$rule = new NetefxValidatorRuleFUNCTION('IsDefault', _t($this->class . '.UNIQUEFIELD','this field must be unique'), null, $function);
return new NetefxValidator($rule);

@lx-berlin we might need to make that more clear in the docs?