id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
37011	The presence of a non-readonly non-editable field in ModelAdmin fails at runtime and has no system check	Andrew Northall		"In `ModelAdmin`, several field configuration errors (such as adding an non-existent field to a `ModelAdmin` `fields` or `fieldsets` attribute) are [https://github.com/django/django/blob/edd899786851f6285abbc3c272f4f5ec0e48a74c/django/contrib/admin/checks.py#L323 covered by system checks] in `contrib/admin/checks.py`. We also have a system check for [https://github.com/django/django/blob/edd899786851f6285abbc3c272f4f5ec0e48a74c/django/contrib/admin/checks.py#L1172 non-editable fields in the list_editable attribute (E125)]. However, a common runtime failure is that a model field which has `editable=False` set in the model is either:

- added to a `ModelAdmin` which does not specify `fields` or `fieldsets` attributes and does not include it in `readonly_fields` or `excludes`, or
- added to a `ModelAdmin` which specifies `fields` or `fieldsets` attributes with this non-editable field included, but the field is omitted from `readonly_fields`.

In simpler terms, any time a field which is non-editable on the model, and not marked as read only appears in change form, this will result in the following error when accessing the create or update views for this `ModelAdmin`:

{{{
FieldError at /admin/app/modelname/add/
'fieldname' cannot be specified for ModelName model form as it is a non-editable field. Check fields/fieldsets/exclude attributes of class ImageTestAdmin.
}}}

It would make sense to me that, at a minimum, we should add a system check for this error to bring the detection in line with other `ModelAdmin` field configuration errors and avoid silent failures at runtime - or perhaps there could be a discussion as to whether the default behaviour could or should be to simply mark these fields as read only by default?"	Bug	closed	contrib.admin	6.0	Normal	needsinfo	system check	Andrew Northall	Unreviewed	0	0	0	0	0	0