I'm trying to implement a list of foreignKeys in django-nonrel (I'm using mongo as db). 

Here is the code:
-----------------

```
# models.py
from django.db import models
from django_mongodb_engine.contrib import MongoDBManager
from djangotoolbox.fields import ListField

class FriendList(models.Model):
    objects = MongoDBManager()
    list = ListField(models.ForeignKey('AWUser'))

    def add_friend(self, awuser):
        # awuser must be an instance of AWUser - I removed tests for more clarity
        self.list.append(awuser)
        self.save()

class AWUser(models.Model):
    objects = CustomUserManager()
    user = EmbeddedModelField('User')
    friends = EmbeddedModelField('FriendList')

```

The problem is that when I call *user.friends.add\_friend(user1)*, I have the error *"AttributeError: 'str' object has no attribute '\_meta'"*. 

Breaking example (made using ./manage shell console):
-----------------------------------------------------

```
$>user = AWUser.objects.all()[0]
$>user1 = AWUser.objects.all()[1]
$>user.friends.add_friend(user1)
#ask me if you need the complete error - I don't put it more more clarity
AttributeError: 'str' object has no attribute '_meta'

```

What I basically need is to create friend lists.  

Please feel free to recommend a different implementation if you think mine is not good. :) I would love to have my implementation working though...  

Also, I did not put all the variables of AWUser for more clarity but I can add them if necessary.

Related project dependencies:
-----------------------------

* django 1.3.1 (installed as django-nonrel)
* django-mongodb-engine 0.4.0
* djangotoolbox==0.9.2
* List item
* pymongo==2.1.1

Thanks for your help.

UPDATE:
-------

I tried to change the code as said in the post "[ListField with ForeignField in django-nonrel](https://stackoverflow.com/questions/14101834/listfield-with-foreignfield-in-django-nonrel?rq=1)" but I still have the same error...