Accessing url of ImageField via values() method on django queryset

Question

I have a data model in Django where I save photos uploaded by users. There's an attribute called image_file in the Photo model (of the type ImageField) where - among other things - the image's url is stored. I can successfully access this url with item.image_file.url in the template (and view) for instance.

However, I can't seem to be able to do the following in the view:

Photo.objects.filter(owner=user).order_by('-id').values('id','image_file.url')[:10]

I.e. For a particular user, I'm trying to get the 10 latest photo objects' image urls along with object ids. This gives me FieldError: Cannot resolve keyword 'image_file.url' into field. Shouldn't this have worked?

I understand I can retrieve the entire object and do the filtering in the template, but I felt it's more optimal to solely retrieve the fields I actually need instead of the full object.

p.s. it's a postgresql backend and the underlying Storage class has been over-ridden

Answer 1

The url is a property, not a value in the database (FileField code) which is why you can't get to it from values(). As far as I can see, you'd have to get the url value separately...

You might want to take a look at only() though. If you go that route, you should probably watch the SQL queries with something like Django Debug Toolbar. If the url property tries to retrieve a field that wasn't included in only(), it will likely make a separate SQL call.