problem with filtering in a referenceproperty dropdown - Django

I have the following problem. I have a contact class that different users can tag with their own topics:

class Contact(db.Model): 
    contact_date = db.DateProperty(auto_now_add=True) 
    remarks = db.TextProperty() 
    topic = db.ReferenceProperty(Topic) 
class Topic(db.Model): 
    topic = db.StringProperty(required=True) 
    description = db.TextProperty() 
    owner = db.ReferenceProperty(User, collection_name='topic_set') 
    def __unicode__(self): 
        return '%s' % (self.topic) 

In the form for this i want to only show the Topics for a certain user

class ContactForm(forms.开发者_StackOverflowModelForm): 
    def __init__(self, user_filter,  *args, **kwargs): 
        self.base_fields['topic'].queryset = Topic.all().filter('owner 
= ', user_filter) 
        super(ContactForm, self).__init__(*args, **kwargs) 

I then call the ContactForm from the view as follows:

form = ContactForm(user_filter = request.user.key())

This all works as expected. However when I submit the form I get:

Caught an exception while rendering: Unsupported type for property  : 
<class 'django.http.QueryDict'> 

Am I doing something wrong? Is this some problem with appengine django implementation? Peter

A Contact can have one Topic and one Topic only. As you explained:

I have a contact class that different users can tag with their own topics

I would move the ReferenceProperty to the Topic class:

class Topic(db.Model): 
    contact = db.ReferenceProperty(Contact) 

Now one Contact can have multiple Topics.

Your exception comes from assigning a property with a Request Query Dictionary. This probably comes from declaring user_filter as an argument, but using it as a keywords argument. It should be:

form = ContactForm(request.user.key())

But as stated above, first you should revise your models.