# coding: utf-8
from __future__ import absolute_import
from __future__ import unicode_literals
from typing import Text
try:
from django.utils.translation import ugettext as _
except Exception:
def _(text):
return text
from . import registry
[docs]class MachineMixin(object):
"""This mixing allows a model to automatically instantiate and assign an
``StateMachine``.
"""
state_field_name = "state" # type: Text
"""The model's state field name that will hold the state value."""
state_machine_name = None # type: Text
"""A fully qualified name of the class, where it can be imported."""
state_machine_attr = "statemachine" # type: Text
"""Name of the model's attribute that will hold the machine instance."""
def __init__(self, *args, **kwargs):
super(MachineMixin, self).__init__(*args, **kwargs)
if not self.state_machine_name:
raise ValueError(
_("{!r} is not a valid state machine name.").format(
self.state_machine_name
)
)
machine_cls = registry.get_machine_cls(self.state_machine_name)
setattr(
self,
self.state_machine_attr,
machine_cls(self, state_field=self.state_field_name),
)