Fixed #2259 -- Made manually specified primary keys readonly in the admin. #19675

Jkhall81 · 2025-07-26T03:12:04Z

Trac ticket number

Branch description

When editing a model instance in the Django admin, manually specified primary key fields (e.g. CharField(primary_key=True)) should not be editable. Without this fix, users can mistakenly change a model's PK, which can cause errors or lead to duplicate records.

This patch updates BaseModelAdmin.get_readonly_fields() to automatically mark such PKs as readonly if they are not auto-generated and not already in the readonly fields.

This change was verified against existing admin inline tests (test_char_pk_inline, test_integer_pk_inline), which initially failed due to the patch, and the logic was adjusted to restore their passing state.

Checklist

[x ] This PR targets the main branch.
[x ] The commit message is written in past tense, mentions the ticket number, and ends with a period.
[x ] I have checked the "Has patch" ticket flag in the Trac system.
I have added or updated relevant tests.
I have added or updated relevant docs, including release notes if applicable.
I have attached screenshots in both light and dark modes for any UI changes.

…omatic zoom issue in mobile Safari.

…dmin change forms.

A

nezhar · 2025-07-29T05:54:56Z

django/contrib/admin/options.py

@@ -418,7 +418,22 @@ def get_readonly_fields(self, request, obj=None):
        """
        Hook for specifying custom readonly fields.
        """
-        return self.readonly_fields


It works on my test project, and it should not affect existing overrides. It also provides the option to fall back to the initial behavior:

def get_readonly_fields(self, request, obj=None): return self.readonly_fields

nezhar · 2025-07-29T06:02:32Z

django/contrib/admin/options.py

+
+        # Only add PK to readonly if:
+        # - editing an existing object
+        # - PK is not auto-created


Any particular reason why an auto_created pk needs to be excluded?

auto_created pks are already not editable in the admin.

sarahboyce

Thank you for the PR
This doesn't seem to be working fully for inlines.
Given the models:

class State(models.Model):
    label = models.CharField(max_length=255)


class StatePKModel(models.Model):
    id = models.IntegerField(primary_key=True)
    state = models.ForeignKey(State, related_name="pk_state_model", on_delete=models.CASCADE)

and admin

class StatePKModelInline(admin.TabularInline):
    model = StatePKModel


@admin.register(State)
class StateAdmin(admin.ModelAdmin):
    inlines = [StatePKModelInline,]

I can edit the id in the inline

sarahboyce · 2025-07-29T08:37:39Z

django/contrib/admin/static/admin/css/base.css

+label {
+    font-size: 1rem;
+}
+


This change looks to be unrelated to the ticket

That was my bad. Fixed this css thing (was from a year old PR). Also, I confirmed with a test that manually defined Pks are readonly in inlines when editing existing objects.

charettes · 2025-07-29T17:46:07Z

django/contrib/admin/options.py

@@ -418,7 +418,22 @@ def get_readonly_fields(self, request, obj=None):
        """
        Hook for specifying custom readonly fields.
        """
-        return self.readonly_fields
+        readonly = self.readonly_fields
+        pk_field = self.model._meta.pk


This should account for composite primary keys now and use _meta.pk_fields.

Thanks! Updated to use _meta.pk_fields for future composite PK support, with fallback to _meta.pk for compatibility.

Updated to use _meta.pk_fields for future composite PK support, with fallback to _meta.pk for compatibility.

No need for a fallback, see the docs.

fallback removed.

sarahboyce · 2025-08-05T11:38:48Z

Thank you for the PR This doesn't seem to be working fully for inlines. Given the models:

class State(models.Model):
    label = models.CharField(max_length=255)


class StatePKModel(models.Model):
    id = models.IntegerField(primary_key=True)
    state = models.ForeignKey(State, related_name="pk_state_model", on_delete=models.CASCADE)

and admin

class StatePKModelInline(admin.TabularInline):
    model = StatePKModel


@admin.register(State)
class StateAdmin(admin.ModelAdmin):
    inlines = [StatePKModelInline,]

I can edit the id in the inline

This is still not fixed unfortunately

Jkhall81 · 2025-08-05T13:16:29Z

Thanks for the feedback. Just to clarify -- the original Trac ticket #2259 doesn't mention inlines at all. The bug, as described and discussed over the years, is focused on making manually defined primary key fields read-only in the Django admin when editing existing objects.

The root issue was that those fields were editable, changing them would silently insert a new object instead of updating the original -- without any error or indication. This has been fixed by marking such fields as read-only in ModelAdmin when editing.

inlines were only brought up in two comments (comments 29 and 54) over the 19 years of discussion on the ticket. So I'm a little confused about why inlines are being brought up.

That being said. I can investigate a follow up fix for inlines.

Jkhall81 · 2025-08-05T13:52:14Z

So I tried making manually-defined primary key fields (including composite PKs) readyonly when editing inlines by overriding InlineModelAdmin.get_readonly_fields() and adding a help method to identify and return PK field names. This worked but lead to the PK fields being entirely hidden in the Django Admin. Which I'm fairly sure you all don't want.

I'm happy with the resolution as it stands and would rather not pursue additional inline-specific logic here.

sarahboyce · 2025-08-06T08:55:26Z

The root issue was that those fields were editable, changing them would silently insert a new object instead of updating the original -- without any error or indication. This has been fixed by marking such fields as read-only in ModelAdmin when editing.

This issue, as described, is present for inlines. As you mentioned, it has been mentioned a couple of times in the ticket discussion. This was also a reason why some PRs previously didn't continue as they were missing a solution for this problem
The ticket is "Primary keys should be readonly by default in admin", and inlines are part of the admin
Currently, the solution doesn't resolve fix the ticket for me

Jkhall81 and others added 4 commits March 24, 2024 11:06

Added CSS rule for label element making font-size 1rem to address aut…

51badee

…omatic zoom issue in mobile Safari.

Merge branch 'django:main' into main

bcbfd96

Fixed django#2259 -- Made manually defined primary keys readonly in a…

89b67a3

…dmin change forms.

Fixed django#2259 -- Made non-auto fields readonly in admin

7a78c93

A

Jkhall81 force-pushed the 2259-readonly-manual-pk-admin branch from 094817a to 7a78c93 Compare July 26, 2025 03:24

Adjusted test to match readonly PK behavior in admin (django#2259)

25fae5e

nezhar reviewed Jul 29, 2025

View reviewed changes

sarahboyce added the selenium Apply to have Selenium tests run on a PR label Jul 29, 2025

sarahboyce reviewed Jul 29, 2025

View reviewed changes

charettes reviewed Jul 29, 2025

View reviewed changes

Jkhall81 force-pushed the 2259-readonly-manual-pk-admin branch from 893d265 to 262ca22 Compare July 29, 2025 18:36

Fixed 2259 -- Made manually defined PKs readonly in admin inlines.

2153973

Jkhall81 force-pushed the 2259-readonly-manual-pk-admin branch from 262ca22 to 2153973 Compare July 29, 2025 18:50

Jkhall81 requested a review from sarahboyce July 30, 2025 12:39

Added get_readonly_fields override to InlineModelAdmin for manual PKs.

2085066

Jkhall81 force-pushed the 2259-readonly-manual-pk-admin branch from acbe1c3 to 2085066 Compare August 5, 2025 13:50

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Fixed #2259 -- Made manually specified primary keys readonly in the admin. #19675

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