Django使用Case手动控制排序

手动控制排序使用Django update方法，所有涉及的数据每一条都会执行一次SQL update语句，MySQL有case语句可将所有影响的数据进行一次性更改，查看Django文档支持case语句

https://docs.djangoproject.com/en/2.2/ref/models/conditional-expressions/

>>> a_month_ago = date.today() - timedelta(days=30) >>> a_year_ago = date.today() - timedelta(days=365) >>> # Update the account_type for each Client from the registration date >>> Client.objects.update( ... account_type=Case( ... When(registered_on__lte=a_year_ago,... then=Value(Client.PLATINUM)),... When(registered_on__lte=a_month_ago,... then=Value(Client.GOLD)),... default=Value(Client.REGULAR) ... ),... ) >>> Client.objects.values_list(‘name‘,‘account_type‘) <QuerySet [(‘Jane Doe‘,‘G‘),(‘James Smith‘,‘R‘),(‘Jack Black‘,‘P‘)]>

根据示例编写自己的应用

增加新数据：

max_sort = Kol.objects.filter(channel_type_kol=kol_type).order_by(‘sort‘).last().sort
if sort > max_sort:
????dif_value = max_sort + 1
elif 0 < sort < max_sort + 1:
????Kol.objects.filter(channel_type_kol=kol_type).update(

????????sort=Case(

????????????When(sort__gte=sort,

?????????????????then=F(‘sort‘) + 1),

????????????default=F(‘sort‘)
????????)
????)
????dif_value = sort

更改排序：

max_sort = Kol.objects.filter(channel_type_kol=channel_type).order_by(‘sort‘).last().sort
if 0 < new_sort < kol_info.sort:
????Kol.objects.filter(channel_type_kol=channel_type).update(

????????sort=Case(

????????????When(sort__range=[new_sort,kol_info.sort - 1],

????????????default=F(‘sort‘)
????????)
????)
????kol_info.sort = new_sort
????kol_info.save()

elif kol_info.sort < new_sort < max_sort + 1:
????Kol.objects.filter(channel_type_kol=channel_type).update(

????????sort=Case(

????????????When(sort__range=[kol_info.sort + 1,new_sort],

?????????????????then=F(‘sort‘) - 1),

????????????default=F(‘sort‘)
????????)
????)
????kol_info.sort = new_sort
????kol_info.save()

删除一条数据：

info = Kol.objects.get(id=id)Kol.objects.filter(channel_type_kol=info.channel_type_kol).update(????sort=Case(????????When(sort__gt=info.sort,?????????????then=F(‘sort‘) - 1),????????default=F(‘sort‘)????))info.delete()