Question

在我们的项目中，我们使用软删除（模型上的is_deleted属性）。在创建新模型之前，我想首先检查它是否已经存在并删除，如果是这样 - 设置is_deleted = False并保存已存在的模型。所以我决定覆盖模型'save'方法。（不是View Create，因为它不仅适用于请求）问题是为所有操作（创建，更新，删除）调用'save（）'。有没有办法只能在create？

上调用重写方法

class Model(BaseModel):
    title = models.CharField(max_length=200)
    identifier = models.CharField(max_length=15)

    def save(self, *args, **kwargs):
        try:                                               
            existing_model = Model.objects.active_and_deleted().get(                                                        identifier=self.identifier)

            if self.is_deleted is False:
                existing_model.is_deleted = False
                existing_model.title = self.title
                existing_model.created_at = self.created_at
                existing_model.updated_at = self.updated_at
                existing_model.created_by = self.created_by
                existing_model.deleted_at = None
                super(Model, existing_model).save(args, kwargs)
        except Model.DoesNotExist:
            # in case the Nodel wasn't already exist - continue
            pass
        super(Model, self).save(*args, **kwargs)

Answer 1

你的问题的答案，＆＃34;有没有办法只能在创建时调用被覆盖的方法？＆＃34;是这样的：

    def save(self, *args, **kwargs):

        if not self.id:
            # Object is a new instance

        return super(Model, self).save(*args, **kwargs)

但这里还有其他问题。例如，您的模型不应被命名为＃34; Model＆＃34 ;.

Answer 2

检查self.pk是否可以做你想做的事，这是一个例子：

class ModelName(mdoels.Model):
    title = models.CharField(max_length=200)
    identifier = models.CharField(max_length=15)

    def save(self, *args, **kwargs):
        if self.pk is None:  # Adding of a new instance
            # let's say we compare instances by `title`
            # you can use other fields for the comparison
            possible_old_instance = Model.objects.filter(title__iexact=self.title)                                            
            if possible_old_instance.exists():
                existing_model = possible_old_instance.first()
                existing_model.is_deleted = False
                existing_model.title = self.title
                existing_model.created_at = self.created_at
                existing_model.updated_at = self.updated_at
                existing_model.created_by = self.created_by
                existing_model.deleted_at = None
                existing_model.save()
                # Nothing happens, we don't call save() method
            else:
                # in case the Model doesn't exist
                super(ModelName, self).save(*args, **kwargs)
        else:
            super(ModelName, self).save(*args, **kwargs)

Django - 覆盖模型save（）

2 个答案: