Opened 21 months ago

Last modified 3 weeks ago

#29087 assigned Bug

Impossible to delete pending new inline in admin when invalid (delete button missing)

Reported by: Owen Heisler Owned by: frnhr
Component: contrib.admin Version: 2.0
Severity: Normal Keywords:
Cc: Triage Stage: Ready for checkin
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: yes

Description (last modified by frnhr)

When adding a new inline record in the Django Admin, it is impossible to delete the record if it has had a validation error. This is the most evident to the user if he/she accidentally attempts to use the wrong inline for some data. For example, if a ContactAdmin has both PhoneInline and EmailInline, the user may accidentally enter a phone number in an EmailInline record. When attempting to submit the changes, a validation error is raised. Seeing the problem, the user would now like to just delete the new record that is pending. However, at this point there is no Delete button. Thus the user is forced to either (a) reload the change page, discarding any other unrelated pending changes on the page; or (b) change the data to make it valid, click Save and continue editing, and then delete the offending record before finally saving the changes again.

Test code

Consider the following code, where the Django Admin provides access to a Groups page with a Persons inline.

models.py:

from django.db import models

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

class Person(models.Model):
    group = models.ForeignKey(Group, on_delete=models.CASCADE)
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=30)

admin.py:

from django.contrib import admin
from .models import *

class PersonInline(admin.StackedInline):
    model = Person
    extra = 0

@admin.register(Group)
class GroupAdmin(admin.ModelAdmin):
    inlines = [PersonInline]

Steps to reproduce

  1. Go to the Group add page (for example, <http://localhost:8000/admin/myapp/group/add/>). Enter a Group name, add a Person with first_name and last_name, and click Save and continue editing.
  2. Change the Group name. Add a second Person for the group, but enter a first_name only. A delete button (X icon) is available to discard the pending record: https://s13.postimg.org/6wv1azzyv/image.png
  3. Click SAVE. There will be a validation error, as expected, because last_name is not provided. However, the Delete button is missing: https://s13.postimg.org/3q0hrduyf/image.png
  4. The user is now forced to either (a) fix the validation error or (b) reload the page, discarding all unrelated changes on the page. It is not possible for the user to fix the validation error by simply canceling/deleting the pending new record.

It is actually worse than that…

Another cause of validation errors can be uniqueness constraints. These errors can be difficult to fix and sometimes actually cannot be fixed. So it is totally possible that because of a validation error the user is forced to reload the page, there is no other choice.

Building on the models above, here is an example of a validation error that can be unsalvageable for users without the create permission for groups. New Council model is added, a foreign key from Person to Council is created and also a constraint with unique_together = ('council', 'group') is set.

https://i.ibb.co/K2ndRGT/Screenshot-2019-08-30-at-21-08-13.png

Change History (8)

comment:1 Changed 21 months ago by Tim Graham

Triage Stage: UnreviewedAccepted

comment:4 Changed 5 months ago by frnhr

Owner: set to frnhr
Status: newassigned

comment:5 Changed 4 months ago by frnhr

Has patch: set
Last edited 8 weeks ago by frnhr (previous) (diff)

comment:6 Changed 8 weeks ago by frnhr

Description: modified (diff)

comment:7 Changed 8 weeks ago by frnhr

Description: modified (diff)

comment:8 Changed 3 weeks ago by Carlton Gibson

Patch needs improvement: set

Fix should address the CSS TabularInline too. (This has the same issue.) Also, the PR includes a significant refactoring, which should be in a separate commit.
But other than that, looks goods. (Works 🙂)

Last edited 3 weeks ago by Carlton Gibson (previous) (diff)

comment:9 Changed 3 weeks ago by frnhr

Patch needs improvement: unset

PR edited

comment:10 Changed 3 weeks ago by Carlton Gibson

Triage Stage: AcceptedReady for checkin

PR is ready to go.

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