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
25299	Admin crash with the name of a reverse accessor in list_display	Sven Coenye	Tim Graham	"In contrast to Django 1.7, Django 1.8 does not allow callables in list_display to have the same name as a relation related_name on a model.

Starting with 
{{{
class SupportItem(models.Model):
    description = models.CharField(max_length=30)

class Hardware(SupportItem):
    tag = models.IntegerField(unique=True)
}}}
and
{{{
class Placement(models.Model):
    support_item = models.ForeignKey(""SupportItem"")
    place_date   = models.DateTimeField()
    location     = models.CharField(max_length=50, null=True, blank=True)
}}}
I have defined a view on the database exposed in Django as
{{{
class HardwareLastAssigned(models.Model):
    hardware = models.OneToOneField(Hardware, primary_key=True,
                                    db_column='support_item_id', 
                                    related_name='last_assigned')
    location = models.CharField(max_length=50, blank=True)
}}}
which gives the last location a hardware item was deployed to. 

Under Django 1.7, the following admin code produces a changelist showing each piece of hardware and its current location:
{{{
class HardwareAdmin(NavigableModelAdmin):
    list_display = ['tag', 'placement']
    list_display_links = list_display
    search_fields = ['tag', 'last_assigned__location']
    form = HardwareForm
    ...
    def placement(self, obj):
        return obj.last_assigned.location
    
    def get_queryset(self, request):
        hardware = super(HardwareAdmin, self).get_queryset(request)
        hardware = hardware.select_related(""last_assigned"")

        return hardware
}}}

Following an upgrade to Django 1.8, the same code crashes with this exception:
    AttributeError: 'Hardware' object has no attribute 'placement' 
in
    File ""/home/django/python2.7-django1.8/lib/python2.7/site-packages/django/contrib/admin/utils.py"", line 288, in lookup_field
    value = getattr(obj, name)

The cause lies in Options.get_field() (django.db.models.options) which under 1.7 only recognized true fields on the model at hand (Hardware), whereas under 1.8, it also reports related models as fields on the model. However, lookup_field can only handle true fields and triggers the exception.

A workaround is to rename the callable so it does not match any related names which may be associated with the model. 

The change was made in commit fb48eb05816b1ac87d58696cdfe48be18c901f16 as part of the formalizations of the _meta API. 

If nothing else can be done, it may be worth a mention in the list_display documentation as this restriction is not at all obvious (to me) based on the current docs and the 1.8 release notes. 
"	Bug	closed	contrib.admin	1.8	Release blocker	fixed	list_display callable name		Accepted	1	0	0	0	0	0