The logic is of the model is:
Building
has many Rooms
Room
may be inside another Room
(a closet, for instance--ForeignKey on 'self') Room
can only be inside another Room
in the same building (this is the tricky part) Here's the code I have:
#spaces/models.py
from django.db import models
class Building(models.Model):
name=models.CharField(max_length=32)
def __unicode__(self):
return self.name
class Room(models.Model):
number=models.CharField(max_length=8)
building=models.ForeignKey(Building)
inside_room=models.ForeignKey('self',blank=True,null=True)
def __unicode__(self):
return self.number
and:
#spaces/admin.py
from ex.spaces.models import Building, Room
from django.contrib import admin
class RoomAdmin(admin.ModelAdmin):
pass
class RoomInline(admin.TabularInline):
model = Room
extra = 2
class BuildingAdmin(admin.ModelAdmin):
inlines=[RoomInline]
admin.site.register(Building, BuildingAdmin)
admin.site.register(Room)
The inline will display only rooms in the current building (which is what I want). The problem, though, is that for the inside_room
drop down, it displays all of the rooms in the Rooms table (including those in other buildings).
In the inline of rooms
, I need to limit the inside_room
choices to only rooms
which are in the current building
(the building record currently being altered by the main BuildingAdmin
form).
I can't figure out a way to do it with either a limit_choices_to
in the model, nor can I figure out how exactly to override the admin's inline formset properly (I feel like I should be somehow create a custom inline form, pass the building_id of the main form to the custom inline, then limit the queryset for the field's choices based on that--but I just can't wrap my head around how to do it).
Maybe this is too complex for the admin site, but it seems like something that would be generally useful...
Used request instance as temporary container for obj. Overrided Inline method formfield_for_foreignkey to modify queryset. This works at least on django 1.2.3.
class RoomInline(admin.TabularInline):
model = Room
def formfield_for_foreignkey(self, db_field, request=None, **kwargs):
field = super(RoomInline, self).formfield_for_foreignkey(db_field, request, **kwargs)
if db_field.name == 'inside_room':
if request._obj_ is not None:
field.queryset = field.queryset.filter(building__exact = request._obj_)
else:
field.queryset = field.queryset.none()
return field
class BuildingAdmin(admin.ModelAdmin):
inlines = (RoomInline,)
def get_form(self, request, obj=None, **kwargs):
# just save obj reference for future processing in Inline
request._obj_ = obj
return super(BuildingAdmin, self).get_form(request, obj, **kwargs)