Django工作流引擎使用信号和Celery-django

Question

我正在努力实现一个工作流引擎到我的项目中，我的尝试的主要目的是创建一个便携式应用程序。有些东西，我将来可以放入任何其他项目中，然后将工作流程附加到项目中的不同模型中并使其运行。

我试图想到一种方法，但它似乎并不是完美的设置。我想在我的项目中创建一个工作流应用程序，附加两种模型，其中一些将包含工作流（工作流，步骤，操作）的设置，其他模型将包含实例/事务。

下面是我的工作流程/ models.py

from django.db import models 
from django.contrib.contenttypes.models import ContentType 
from django.contrib.contenttypes import generic 
import signals 


################################ 
# Workflow engine models 
################################ 

class Signal_Listener(models.Model): 
    LISTENING_ON = (
    ('I', 'INSERT'), 
    ('U', 'UPDATE'), 
    ('D', 'DELETE'), 
    ('S', 'SELECT'), 
    ('A', 'ANY QUERY'), 
    ('L', 'ANY DDL'), 
    ) 

    table_name = models.CharField(max_length=100) 
    listening_to = models.CharField(max_length=1, choices=LISTENING_ON) 

    class Meta: 
     unique_together = (("table_name", "listening_to"),) 

    def __unicode__(self): 
     return '%s - %s' % (self.table_name, self.listening_to) 

class Action(models.Model): 
    ACTION_TYPE_CHOICES = (
    ('P', 'Python Script' ), 
    ('C', 'Class name'  ), 
    ) 
    name = models.CharField(max_length=100) 
    action_type = models.CharField(max_length=1, choices=ACTION_TYPE_CHOICES) 
    audit_obj = generic.GenericRelation('core.Audit', editable=False) 

class Steps(models.Model): 
    sequence = models.IntegerField() 
    Action = models.ForeignKey(Action) 
    Signal_Listener = models.ForeignKey(Signal_Listener) 

class Process(models.Model): 
## TODO: Document 
# Processes class is used to store information about the process itself. 
# Or in another word, the workflow name. 
    WF_TYPE_LIST = (
    ('P', 'Python-API'), 
    ) 

    name = models.CharField(max_length=30) 
    is_active = models.BooleanField() 
    wf_type = models.CharField(max_length=1, choices=WF_TYPE_LIST) 
    audit_obj = generic.GenericRelation('core.Audit', editable=False) 
    listening_to = models.ForeignKey(Steps) 



################################ 
# Workflow transactions models 
################################ 

class Instance(models.Model): 
## TODO: Document 
# Re 
    INSTANCE_STATUS = (
    ('I', 'In Progress'), 
    ('C', 'Cancelled' ), 
    ('A', 'Archived' ), # Old completed tasks can be archived 
    ('P', 'Pending' ), 
    ('O', 'Completed' ) 
    ) 

    id = models.CharField(max_length=200, primary_key=True) 
    status = models.CharField(max_length=1, choices=INSTANCE_STATUS, db_index=True) 
    audit_obj = generic.GenericRelation('core.Audit', editable=False) 

    def save(self, *args, **kwargs): 
    # on new records generate a new uuid 
     if self.id is None or self.id.__len__() is 0: 
      import uuid 

      self.id = uuid.uuid4().__str__() 
     super(Instances, self).save(*args, **kwargs) 

class Task(models.Model): 
    TASK_STATUS = (
    ('S', 'Assigned' ), 
    ('I', 'In Progress'), 
    ('P', 'Pending' ), 
    ('C', 'Cancelled' ), 
    ('A', 'Archived' ), # Old completed tasks can be archived 
    ('O', 'Completed' ) 
    ) 
    name = models.CharField(max_length=100) 
    instance = models.ForeignKey(Instance) 
    status = models.CharField(max_length=1, choices=TASK_STATUS) 
    bio = models.CharField(max_length=100) 
    audit_obj = generic.GenericRelation('core.Audit', editable=False) 

，我也有一个工作流/ signals.py

""" 
     Workflow Signals 
      Will be used to monitor all inserts, update, delete or select statements 
      If an action is attached to that particular table, it will be inserted Celery-Tasks distribution. 
    """ 
    from django.db.models.signals import post_save, post_delete 
    from django.core.cache import cache 


    def workflow_post_init_listener(sender, **kwargs): 
     try: 

      if cache.get('wf_listner_cache_%s' % kwargs['instance']._meta.db_table): 
       pass 
      else: 
       record = 'Signal_Listener'.objects.get(table_name__exact=kwargs['instance']._meta.db_table) 
# am not sure what to do next! 
     except 'Signal_Listener'.DoesNotExist: 
      # TODO: Error logging 
      pass 

    post_save.connect(workflow_post_init_listener, dispatch_uid="workflow.models.listener.save") 

我觉得我的模型设计可能需要提高为好。我可以在几种情况下使用，并且我想从批准周期开始，例如，我可以在signal_listener中插入table_name/model_name以监视新插入。如果是这样，我会触发一个特定的工作流程。

至于行动，我明白行动将需要发展。也许我需要在工作流应用程序下创建一个操作文件夹，将每个操作放在一个类中。每个人都会完成发送电子邮件，存档，更新数据库值的特殊任务。如果你正在重新发明轮子，并且如果有这样的东西已经被开发出来，任何人都可以建议，我会更乐意通过它。例如，你可以去看看的zope.wfmc

最好的问候，

Answer 1

（http://pypi.python.org/pypi/zope.wfmc）：这是一个工作流管理联盟的实现 可以在XPDL上定义的工作流程。