def validate_python(self, value, state):

        if value != authentication_token():

            raise formencode.Invalid(self.message('invalid_token', state,

                                            search_number=value), value, state)

def ValidUsername(edit, old_data):             

    class _ValidUsername(formencode.validators.FancyValidator):

        def validate_python(self, value, state):

            if value in ['default', 'new_user']:

                raise formencode.Invalid(_('Invalid username'), value, state)

            #check if user is uniq

            sa = meta.Session

            old_un = None

            if edit:

                old_un = sa.query(User).get(old_data.get('user_id')).username

            if old_un != value or not edit:    

                if sa.query(User).filter(User.username == value).scalar():

                    raise formencode.Invalid(_('This username already exists') ,

                                             value, state)

            meta.Session.remove()

    return _ValidUsername   

class ValidPassword(formencode.validators.FancyValidator):

    def to_python(self, value, state):

        if value:

            return get_crypt_password(value)

class ValidAuth(formencode.validators.FancyValidator):

    messages = {

            'invalid_password':_('invalid password'),

            'invalid_login':_('invalid user name'),

            'disabled_account':_('Your acccount is disabled')

            }

    #error mapping

    e_dict = {'username':messages['invalid_login'],

              'password':messages['invalid_password']}

    e_dict_disable = {'username':messages['disabled_account']}

    def validate_python(self, value, state):

        password = value['password']

        username = value['username']

            user = UserModel().get_user_by_name(username)

            raise formencode.Invalid(self.message('invalid_password',

                                     state=State_obj), value, state,

                                     error_dict=self.e_dict)            

        if user:

            if user.active:

                if user.username == username and check_password(password, 

                                                                user.password):

                    return value

                else:

                    log.warning('user %s not authenticated', username)

                    raise formencode.Invalid(self.message('invalid_password',

                                             state=State_obj), value, state,

                                             error_dict=self.e_dict)

            else:

                log.warning('user %s is disabled', username)

                raise formencode.Invalid(self.message('disabled_account',

                                         state=State_obj),

                                         value, state,

                                         error_dict=self.e_dict_disable)

class ValidRepoUser(formencode.validators.FancyValidator):

    def to_python(self, value, state):

        try:

            self.user_db = meta.Session.query(User)\

                .filter(User.active == True)\

                .filter(User.username == value).one()

        except Exception:

            raise formencode.Invalid(_('This username is not valid'),

                                     value, state)

        finally:

            meta.Session.remove()

        return self.user_db.user_id

def ValidRepoName(edit, old_data):    

    class _ValidRepoName(formencode.validators.FancyValidator):

        def to_python(self, value, state):

            slug = h.repo_name_slug(value)

            if slug in ['_admin']:

                raise formencode.Invalid(_('This repository name is disallowed'),

                                         value, state)

            if old_data.get('repo_name') != value or not edit:    

                sa = meta.Session

                if sa.query(Repository).filter(Repository.repo_name == slug).scalar():

                    raise formencode.Invalid(_('This repository already exists') ,

                                             value, state)