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Models

CustomBaseModel

This is a common model. By default, CustomBaseModel contains these fields:

• created_at
• updated_at

Almost a default models.Model with two extra fields.

CustomBaseModelWithSoftDelete

This model inherits from CustomBaseModel and provides fake deletion which is probably called SOFT DELETE. This means, when you call model’s delete() method or QuerySet’s delete() method, it acts like delete action but never deletes the data.

Just sets the deleted_at field to NOW.

This works exactly like Django’s delete(). Broadcasts pre_delete and post_delete signals and returns the number of objects marked as deleted and a dictionary with the number of deletion-marks per object type.

You can call hard_delete() method to delete an instance or a queryset actually.

This model uses CustomBaseModelWithSoftDeleteManager as default manager.

How soft-delete works?

When you call .delete() method of a model instance or queryset, model manager sets deleted_at attribute to NOW all the way down through related ForeignKey and ManyToMany fields. This means, you still keep everything.

Nothing is actually deleted, therefore your database constraints are still work fine. When you access deleted (inactive) object from admin site, you’ll see "deleted" text prefix in your related form fields if your related objects are CustomBaseModelWithSoftDelete instances.

When you click recover button in the same page, all related and soft-deleted objects’ deleted_at value will set to NULL and available again.

Please use .actives() queryset method instead of .all(). Why? .all() method is untouched and works as default. When all() called, returning queryset set contains everything event if the deleted_at is NULL or not...

Examples

>>> Post.objects.all()

SELECT "blog_post"."id",
       "blog_post"."created_at",
       "blog_post"."updated_at",
       "blog_post"."deleted_at",
       "blog_post"."author_id",
       "blog_post"."category_id",
       "blog_post"."title",
       "blog_post"."body"
  FROM "blog_post"
 LIMIT 21


Execution time: 0.000950s [Database: default]

<CustomBaseModelWithSoftDeleteQuerySet [
    <Post: Python post 1>, 
    <Post: Python post 2>, 
    <Post: Python post 3>, 
    <Post: Python post 4>,
    :
    :
    :
    <Post: Golang post 4>
]>

>>> Category.objects.all()

SELECT "blog_category"."id",
       "blog_category"."created_at",
       "blog_category"."updated_at",
       "blog_category"."deleted_at",
       "blog_category"."title"
  FROM "blog_category"
 LIMIT 21


Execution time: 0.000643s [Database: default]

<CustomBaseModelWithSoftDeleteQuerySet [<Category: Python>, <Category: Ruby>, <Category: Bash>, <Category: Golang>]>

>>> Tag.objects.all()

SELECT "blog_tag"."id",
       "blog_tag"."created_at",
       "blog_tag"."updated_at",
       "blog_tag"."deleted_at",
       "blog_tag"."name"
  FROM "blog_tag"
 LIMIT 21


Execution time: 0.000519s [Database: default]

<CustomBaseModelWithSoftDeleteQuerySet [<Tag: textmate>, <Tag: pyc>, <Tag: irb>, <Tag: ipython>, <Tag: lock>, <Tag: environment>]>

>>> Category.objects.get(title='Bash').delete()
(9, {'blog.Post_tags': 4, 'blog.Category': 1, 'blog.Post': 4})

>>> Category.objects.delete()
(11, {'blog.Post_tags': 4, 'blog.Category': 3, 'blog.Post': 4})

>>> Category.objects.inactives()

SELECT "blog_category"."id",
       "blog_category"."created_at",
       "blog_category"."updated_at",
       "blog_category"."deleted_at",
       "blog_category"."title"
  FROM "blog_category"
 WHERE "blog_category"."deleted_at" IS NOT NULL
 LIMIT 21


Execution time: 0.000337s [Database: default]

<CustomBaseModelWithSoftDeleteQuerySet [<Category: Bash>]>

>>> Post.objects.inactives()

SELECT "blog_post"."id",
       "blog_post"."created_at",
       "blog_post"."updated_at",
       "blog_post"."deleted_at",
       "blog_post"."author_id",
       "blog_post"."category_id",
       "blog_post"."title",
       "blog_post"."body"
  FROM "blog_post"
 WHERE "blog_post"."deleted_at" IS NOT NULL
 LIMIT 21


Execution time: 0.000387s [Database: default]

<CustomBaseModelWithSoftDeleteQuerySet [<Post: Bash post 1>, <Post: Bash post 2>, <Post: Bash post 3>, <Post: Bash post 4>]>

>>> Category.objects.inactives().undelete()
(9, {'blog.Post_tags': 4, 'blog.Category': 1, 'blog.Post': 4})

>>> Category.objects.inactives()
<CustomBaseModelWithSoftDeleteQuerySet []>

>>> Post.objects.inactives()
<CustomBaseModelWithSoftDeleteQuerySet []>

CustomBaseModelWithSoftDeleteQuerySet has these query options:

• .actives() : filters if CustomBaseModelWithSoftDelete.deleted_at is set to NULL
• .inactives() : filters if CustomBaseModelWithSoftDelete.deleted_at is not set to NULL
• .delete() : soft delete on given object/queryset.
• .undelete() : recover soft deleted on given object/queryset.
• .hard_delete() : this is real delete. this method erases given object/queryset and there is no turning back!.

When soft-delete enabled (during model creation), Django admin will automatically use CustomBaseModelAdminWithSoftDelete which is inherited from: CustomBaseModelAdmin <- admin.ModelAdmin.