How to run "SELECT FOR UPDATE" for the default "Delete selected" in Django Admin Actions?
I have Person
model as shown below:
# "store/models.py"
from django.db import models
class Person(models.Model):
name = models.CharField(max_length=30)
And, this is Person
admin below:
# "store/admin.py"
from django.contrib import admin
from .models import Person
@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):
pass
Then, when clicking Go to go to delete the selected persons as shown below:
Then, clicking Yes I'm sure to delete the selected persons:
Only DELETE
query is run in transaction as shown below:
Now, how can I run SELECT FOR UPDATE
for the default "Delete selected" in Django Admin Actions?
You need to override delete_queryset() with raw queries and @transaction.atomic
as shown below to run SELECT FOR UPDATE
for the default "Delete selected" in Django Admin Actions:
# "store/admin.py"
from django.contrib import admin
from .models import Person
from django.db import transaction
from django.db import connection
@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):
@transaction.atomic # Here
def delete_queryset(self, request, queryset):
ids = ()
if len(queryset) > 1:
for obj in queryset:
ids += (obj.id,)
ids = str(ids)
else:
ids = "(" + str(queryset[0].id) + ")"
with connection.cursor() as cursor: # Here
query = "SELECT * FROM store_person WHERE id IN " + ids + " FOR UPDATE"
cursor.execute(query)
query = "DELETE FROM store_person WHERE id IN " + ids
cursor.execute(query)
Then, when clicking Go to go to delete the selected persons as shown below:
Then, clicking Yes I'm sure to delete the selected persons:
SELECT FOR UPDATE
query and DELETE
query are run in transaction as shown below:
In addition, you can check the default code of delete_queryset() which is not overridden as shown below:
class ModelAdmin(BaseModelAdmin):
# ...
def delete_queryset(self, request, queryset):
"""Given a queryset, delete it from the database."""
queryset.delete()