Django工作流引擎使用信號和Celery-django

Question

我正在努力實現一個工作流引擎到我的項目中，我的嘗試的主要目的是創建一個便攜式應用程序。有些東西，我將來可以放入任何其他項目中，然後將工作流程附加到項目中的不同模型中並使其運行。

我試圖想到一種方法，但它似乎並不是完美的設置。我想在我的項目中創建一個工作流應用程序，附加兩種模型，其中一些將包含工作流（工作流，步驟，操作）的設置，其他模型將包含實例/事務。

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) 

，我也有一個工作流/ 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") 

我覺得我的模型設計可能需要提高爲好。我可以在幾種情況下使用，並且我想從批准週期開始，例如，我可以在signal_listener中插入table_name/model_name以監視新插入。如果是這樣，我會觸發一個特定的工作流程。

至於行動，我明白行動將需要發展。也許我需要在工作流應用程序下創建一個操作文件夾，將每個操作放在一個類中。每個人都會完成發送電子郵件，存檔，更新數據庫值的特殊任務。如果你正在重新發明輪子，並且如果有這樣的東西已經被開發出來，任何人都可以建議，我會更樂意通過它。例如，你可以去看看的zope.wfmc

最好的問候，

Answer 1

（http://pypi.python.org/pypi/zope.wfmc）：這是一個工作流管理聯盟的實現 可以在XPDL上定義的工作流程。