formencode examples ...

forms.py

class UniqueEmailChange(formencode.FancyValidator):
    def validate_python(self, values, c):                
        account = meta.Session.query(Account).filter_by(email=values['email']).first()
        if account and values['profile_id'] not in [profile.id for profile in account.profiles]:
            raise formencode.Invalid(
                'That email address is already in use.',
                values, c, error_dict=dict(email='That email address is already in use.'))
                             
class EditProfileForm(formencode.Schema):
    allow_extra_fields = True
    profile_id = validators.Int()
    first_name = validators.String(not_empty=True)
    last_name = validators.String(not_empty=True)
    email = validators.Email(resolve_domain=False, not_empty=True)
    password = validators.String(if_missing=None)
    password2 = validators.String(if_missing=None)
    phone = formencode.national.USPhoneNumber(if_missing=None)
    dob = validators.DateConverter(if_missing=None)
    gender = validators.Int(min=1, max=2, if_missing=None)   
    is_active = validators.Bool()
    is_admin = validators.Bool()
    is_approved = validators.Bool()
    is_substitute = validators.Bool()
    never_violate_frequency = validators.Bool()
    never_violate_availability = validators.Bool()
    availability = formencode.ForEach(SplitId(if_missing=None))
    max_frequency = validators.Int(if_missing=None)
    works_with = validators.Int(if_missing=None)
    send_new_account_email = validators.Bool()
    vacations = formencode.ForEach(Vacation())
    pre_validators = [formencode.variabledecode.NestedVariables()]    
    chained_validators = [validators.FieldsMatch('password','password2'),
                          UniqueEmailChange()]
    
    def validate_python(self, value, state):
        vacations = value['vacations']
        for vacation in vacations[:]:
            if vacation.values() == [None] * len(vacation.values()):
                vacations.remove(vacation)