[Zope3-Users] Invariants and forms

[NYLAN at gmx.net]

Hello, I'm using an invariant to check if given passwords are equal.

I've found two different examples(see below), but both don't display my given exception message. The only thing i get is the standard error message.

Since this is my first experience with zope, could someone explain to me the correct way to get a custom error message with invariants?

Thanks!!!
I'm using zope version 3.3.1.

First example
(taken from: http://blog.gocept.com/zope3-testen-von-felderuebergreifenden-bedingungen-in-interfaces-mit-zope-formlib/):

class PasswordsAreNotEqual(zope.schema.ValidationError):
    u"""Das Passwort und die Wiederholung sind nicht gleich."""
    zope.interface.implements(zope.app.form.interfaces.IWidgetInputError)

def arePasswordsEqual(obj)
    if obj.password != obj.password2:
        raise PasswordsAreNotEqual

from zope.interface import Interface, invariant

class IUser(Interface):
    password = zope.schema.Password(title=u"Passwort")
    password2 = zope.schema.Password(title=u"Wiederholung des Passworts")

    arePasswordsEqual = invariant(arePasswordsEqual)


Second example
(taken from:
http://blog.gocept.com/zope3-testen-von-felderuebergreifenden-bedingungen-invariants-in-interfaces-mit-zope-formlib-aktualisiert)

import zope.interface

class IUser(zope.interface.Interface):
    password = zope.schema.Password(title=u"Passwort")
    password2 = zope.schema.Password(title=u"Wiederholung des Passworts")

    @zope.interface.invariant
    def arePasswordsEqual(user):
        if user.password != user.password2:
            raise zope.interface.Invalid(
                u"""Das Passwort und die Wiederholung sind nicht gleich.""")
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