'Given the *incoming* primitive data, return the value for this field
that should be validated and transformed to a native value.'

def get_value(self, dictionary):

    if html.is_html_input(dictionary):
        if (self.field_name not in dictionary):
            if getattr(self.root, u'partial', False):
                return empty
            return self.default_empty_html
        ret = dictionary[self.field_name]
        if ((ret == u'') and self.allow_null):
            return (u'' if getattr(self, u'allow_blank', False) else None)
        elif ((ret == u'') and (not self.required)):
            return (u'' if getattr(self, u'allow_blank', False) else empty)
        return ret
    return dictionary.get(self.field_name, empty)
