model:

class Store(models.Model):
  name = models.CharField(max_length = 20)
  class Admin:
    pass
  def __unicode__(self):
    return self.name

class Stock(Store):
  products = models.ManyToManyField(Product)
  class Admin:
    pass
  def __unicode__(self):
    return self.name

class Product(models.Model):
  name = models.CharField(max_length = 128, unique = True)
  parent = models.ForeignKey('self', null = True, blank = True, related_name='children')
  (...)
  def __unicode__(self):
    return self.name

mptt.register(Product, order_insertion_by = ['name'])

admin.py:

from bar.drinkstore.models import Store, Stock

from django.contrib import admin

admin.site.register(Store)
admin.site.register(Stock)

Now when I look at admin site I can select any product from the list. But I'd like to have a limited choice - only leaves. In mptt class there's function:

is_leaf_node() -- returns True if the model instance is a leaf node (it has no children), False otherwise.

But I have no idea how to connect it

I'm trying to make a subclass: in admin.py:

  from bar.drinkstore.models import Store, Stock

  from django.contrib import admin

  admin.site.register(Store)

  class StockAdmin(admin.ModelAdmin):
    def queryset(self, request):
      qs = super(StockAdmin, self).queryset(request).filter(ihavenoideawhatfilter)

    admin.site.register(Stock, StockAdmin)

but I'm not sure if it's right way, and what filter set.