#29087: Impossible to delete pending new inline in admin when invalid (delete
button missing)
-------------------------------+------------------------------------
Reporter: Owen Heisler | Owner: frnhr
Type: Bug | Status: assigned
Component: contrib.admin | Version: 2.0
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 1
-------------------------------+------------------------------------
Description changed by frnhr:
Old description:
> 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:
> {{{#!python
> 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:
> {{{#!python
> 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:
> [[Image(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: [[Image(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.
>
> [[Image(https://i.ibb.co/41gpvgS/Screenshot-2019-08-30-at-21-08-13.png)]]
New description:
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:
{{{#!python
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:
{{{#!python
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: [[Image(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: [[Image(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.
[[Image(https://i.ibb.co/K2ndRGT/Screenshot-2019-08-30-at-21-08-13.png)]]
--
--
Ticket URL: <https://code.djangoproject.com/ticket/29087#comment:7>
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