@classmethod
def add_field(cls, rname, label, model, table, ftype):
    """ Insert a field definition

        :param rname: name of the field
        :param label: label of the field
        :param model: namespace of the model
        :param table: name of the table of the model
        :param ftype: type of the AnyBlok Field
        """
    cls.insert(code=table + '.' + rname, model=model, name=rname, label=
        label, ftype=ftype)
