Django：何时使用保存后的信号自定义保存 [英] Django: When to customize save vs using post-save signal

问题描述

我在数据库中有一系列的测试和案例。每当测试被淘汰时，它将被终止，并且该测试的任何子案例也应该结束。我看到两种方式来实现这一点：

1）修改保存功能以结束日期子案例

2）创建一个侦听器对于测试模型被保存，然后结束日期他们的子案例。

任何理由使用另一个以外的其他？

编辑：我看到这个博客建议在您检查模型的给定值时使用保存方法。因为我正在检查end_date，也许这表明我应该使用自定义保存？

Edit2 ：另外，为了记录，层次结构是协议 - >测试 - >案例 - >计划_执行，任何时候都是end_dated，每个孩子也必须是终止的。我想我最终会为每个人做基本相同的事情。

Edit3 ：事实证明，为了判断当前save（）是结束测试的，我需要访问旧数据和新数据，所以我使用了一个自定义保存。这是它的样子：

  def save（self）：
使用自定义保存结束日期任何subCases
 try：
 orig = Test.objects.get（id = self.id）
 enddated =（not orig.end_date）和self.end_date不是无
除了
 enddated = False 
 
 super（Test，self）.save（）
 
如果结束：
 for case in self.case_set .exclude（end_date__isnull = False）：
 case.end_date = self.end_date 
 case.enddater = self.enddater 
 case.save（）
  
解决方案
我通常使用这个经验法则：
 
 
 
 
 
如果您必须修改数据，以便保存不会失败，请覆盖 save（）（您真的没有其他选项）。例如，在我正在开发的应用程序中，我有一个带有文本字段的模型，其中包含选项列表。这与旧代码接口，并替换具有相似文本字段但具有不同选项列表的旧型号。旧的代码有时会将我的模型从旧模型中选择出来，但是在选择之间有1：1的映射，所以在这种情况下，我可以将选择修改为新的选择。在 save（）中这样做是有意义的。
 
 
否则，如果保存可以无需干预就可以继续进行，保存信号。
 
 
 
I have a series of tests and cases in a database.  Whenever a test is obsoleted, it gets end dated, and any sub-cases of that test should also be end dated.  I see two ways to accomplish this:

1) Modify the save function to end date sub-cases.

2) Create a receiver which listens for Test models being saved, and then end dates their sub-cases.

Any reason to use one other than the other?

Edit: I see this blog post suggests to use the save method whenever you check given values of the model.  Since I'm checking the end_date, maybe that suggests I should use a custom save?

Edit2: Also, for the record, the full hierarchy is Protocol -> Test -> Case -> Planned_Execution, and anytime one is end_dated, every child must also be endDated.  I figure I'll end up doing basically the same thing for each.

Edit3: It turns out that in order to tell whether the current save() is the one that is endDating the Test, I need to have access to the old data and the new data, so I used a custom save.  Here's what it looks like:
def save(self):
    """Use a custom save to end date any subCases"""
    try:
        orig = Test.objects.get(id=self.id)
        enddated = (not orig.end_date) and self.end_date is not None   
    except:
        enddated = False

    super(Test, self).save()

    if enddated:
        for case in self.case_set.exclude(end_date__isnull=False):
            case.end_date = self.end_date
            case.enddater = self.enddater
            case.save()

解决方案
I generally use this rule of thumb:


If you have to modify data so that the save won't fail, then override save() (you don't really have another option). For example, in an app I'm working on, I have a model with a text field that has a list of choices. This interfaces with old code, and replaces an older model that had a similar text field, but with a different list of choices. The old code sometimes passes my model a choice from the older model, but there's a 1:1 mapping between choices, so in such a case I can modify the choice to the new one. Makes sense to do this in save().
Otherwise, if the save can proceed without intervention, I generally use a post-save signal.


                        
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