[Answer]-Denormalizing models in tastypie

The error you are getting is caused by the fact that you are accessing the image attribute of a model class, not instance.

The object that is being dehydrated in the dehydrate method is stored in obj attribute of the bundle parameter. Also, you are trying to filter place_image models to only those with place=1 and cardinality=0 by accessing the image attribute of place_image model class. Such filtering won’t work as image is not a ModelManager instance. You should use objects attribute instead. Furthermore, get() method returns an actual model instance thus a subsequent call to get() will raise AtributeError as your place_image model instances have no attribute get.

So, all in all, your dehydrate should look like this:

def dehydrate(self, bundle):
    bundle.data['image'] = place_image.objects.get(place_id=1, cardinality=0).image
    return bundle

Notice that this code requires the place_image with desired values to exist, otherwise a place_image.DoesNotExist will be thrown.

There is also some redundancy in your models:

• idPlace and idImage can be removed, as django by default creates an AutoField that is a primary key called id when no other primary key fields are defined
• place_image.place field has a redundant to_field parameter, as by default ForeignKey points to a primary key field