如何查询SoftDeletableModel含软删除对象？替代自制方案遇阻

Alright, let's break down how to solve this. You're right that the default SoftDeletableManagerMixin in django-model-utils only filters out soft-deleted objects in its get_queryset method—there's no built-in all_with_deleted functionality. But since you need access to those deleted records for cross-node notifications in your decentralized architecture, here are a couple of clean, maintainable solutions:

1. Custom Manager with all_with_deleted and deleted Methods #

The simplest approach is to extend the existing SoftDeletableManagerMixin to add the methods you need. This preserves the default behavior of hiding soft-deleted objects while giving you explicit access when you need it.

from django.db import models
from model_utils.managers import SoftDeletableManagerMixin, SoftDeletableManager

class CustomSoftDeletableManager(SoftDeletableManagerMixin, models.Manager):
    def all_with_deleted(self):
        # Bypass the soft-delete filter by calling the parent of SoftDeletableManagerMixin
        return super(SoftDeletableManagerMixin, self).get_queryset()
    
    def deleted(self):
        # Optional: Convenience method to fetch only soft-deleted objects
        return self.all_with_deleted().filter(is_removed=True)

# Use this manager in your model
from model_utils.models import SoftDeletableModel

class YourDecentralizedModel(SoftDeletableModel):
    # Your model fields go here (e.g., name, created_at, etc.)
    name = models.CharField(max_length=100)
    
    # Replace the default manager with your custom one
    objects = CustomSoftDeletableManager()

How to Use It: #

• For normal operations (where you don't want soft-deleted objects), use YourDecentralizedModel.objects.all() as usual—it will still exclude deleted records.
• When you need to process soft-deleted objects for cross-node notifications, call YourDecentralizedModel.objects.deleted() to get only the deleted entries, or all_with_deleted() to get every record (deleted and active).

2. Abstract Base Class for Reusability #

If you have multiple models that need this functionality, create an abstract base model so you don't repeat code across your project:

class BaseSoftDeletableModel(SoftDeletableModel):
    objects = CustomSoftDeletableManager()
    
    class Meta:
        abstract = True

# Now inherit from this base model for all your decentralized models
class UserData(BaseSoftDeletableModel):
    # Your fields
    email = models.EmailField(unique=True)

class DeviceRecord(BaseSoftDeletableModel):
    # Your fields
    device_id = models.CharField(max_length=50)

Key Notes for Your Decentralized Setup #

• Avoid Overusing all_with_deleted: Keep the default manager's behavior intact for most business logic to prevent accidental exposure of deleted data. Only use deleted() or all_with_deleted() specifically in your cross-node notification workflows.
• Track Processed Deletions: Consider adding a notification_sent boolean field to your models (or a separate audit log) to mark when you've already sent a deletion notification to other nodes. This prevents duplicate notifications.
• Test Edge Cases: Make sure to write tests that verify:
  • Normal queries exclude soft-deleted objects
  • all_with_deleted() returns all records
  • deleted() returns only soft-deleted records

内容的提问来源于stack exchange，提问作者Csaba Toth