Django: ManyToMany Inline Admin view error

Question

Here are the model definitions:

class ItemBrand(models.Model):
name = models.CharField(max_length = 30, unique = True)

def __unicode__(self):
    return self.name

class WantedItem(models.Model):
name = models.CharField(max_length = 120)
description = models.TextField()
created = models.DateTimeField(auto_now = False, auto_now_add = True)
expires = models.DateTimeField(auto_now = False, auto_now_add = False)
type = models.ForeignKey(ItemType, related_name = "type wanted")

GENDER_CHOICES = (
    (1, 'Male'),
    (2, 'Female')
)

gender = models.IntegerField(choices = GENDER_CHOICES)    
brands = models.ManyToManyField(ItemBrand, related_name = "wantedbrands", symmetrical = False)
colors = models.ManyToManyField(ItemColor)
sizes = models.ManyToManyField(ItemSize)
creator = models.ForeignKey(User, related_name = "wishlist creator")

def __unicode__(self):
    return self.name

Here is the AdminModel code:

class BrandsInline(admin.TabularInline):
model = WantedItem.brands.through

class WantedItemAdmin(admin.ModelAdmin):
list_display = ('name', 'created', 'expires', 'type', 'gender', 'creator')    
search_fields = ('name', 'description')
list_filter = ('created', 'brands',)
ordering = ('-created',)
inlines = [
    BrandsInline,
]
exclude = ('brands',)

This is pulled basically right from the Django docs, and here's the error I am getting:

'ReverseManyRelatedObjectsDescriptor' object has no attribute 'through'

I am at a total loss... any ideas? Even if I literally create a linker table and set the "through" attribute in the Model I get the same error.

Broken?

Answer 1

While it may not be the cause of your error, spaces in the related_name attribute are invalid so I'd try removing those first.

"type wanted" => "type_wanted"

"wishlist creator" => "wishlist_creator"

Answer 2

You need to upgrade Django to the trunk.

Using inlines with many-to-many fields is new in the django development version (see docs).

Using a simplified version of your models, I get the same error as you for Django 1.1.1, but it works on the trunk (revision 11785).

---

As an aside, you don't need to specify symmetrical = False on your ItemBrand ManyToMany field. The symmetrical option is only intended for recursive relationships eg User <-> User.

You may want to have a look at the documentation on related names, and think about renaming them to something more logical as well. If creator is a User object, and want to get the set of wishlists they have created, the default when related_name is not specified is

creator.wishlist_set.all()

with your choice for related_name (when you add the underscore), this changes to

creator.wishlist_creator.all()

but I would recommend related_name='wishlists', in which case you would use

creator.wishlists.all()