How to run "SELECT FOR UPDATE" instead of "SELECT" when changing and deleting data in Django Admin?

Question

I have the code below:

# "store/models.py"

from django.db import models

class Person(models.Model):
    name = models.CharField(max_length=30)

# "store/admin.py"

from django.contrib import admin
from .models import Person

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):
    pass

Then, when changing data as shown below:

SELECT is run instead of SELECT FOR UPDATE as shown below. *I use PostgreSQL and these logs below are the queries of PostgreSQL and you can check On PostgreSQL, how to log queries with transaction queries such as "BEGIN" and "COMMIT":

And, when clicking Delete button of Change person as shown below:

Then clicking Yes, I'm sure button to delete data as shown below:

SELECT is run instead of SELECT FOR UPDATE as shown below:

Now, I want to run SELECT FOR UPDATE instead of SELECT for both cases as shown above.

So, how can I do this?

Answer 1

You need to override get_queryset() with select_for_update() as shown below:

# "store/admin.py"

from django.contrib import admin
from .models import Person

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):
    def get_queryset(self, request):
        qs = super().get_queryset(request)
        
        last_part_of_referer = request.META.get('HTTP_REFERER').split('/')[-2]
        last_part_of_uri = request.build_absolute_uri().split('/')[-2]

        if (last_part_of_referer == "change" and last_part_of_uri == "change") or \
           (last_part_of_referer == "delete" and last_part_of_uri == "delete"):
            qs = qs.select_for_update()
        
        return qs

Then, when changing data as shown below:

SELECT FOR UPDATE is run instead of SELECT as shown below:

And, when clicking Delete button of Change person as shown below:

Then clicking Yes, I'm sure button to delete data as shown below:

SELECT FOR UPDATE is run instead of SELECT as shown below:

Answer 2

To run a SELECT FOR UPDATE query instead of a regular SELECT query in Django Admin, you can use the select_for_update() method on your queryset. This method will lock the rows in the queryset until the transaction is committed or rolled back, preventing other transactions from modifying the data in those rows.