django - query mutliple models for the same field in each in 1 query

Question

Say I have 3 models (Blog, News, Photos) and i want to get the latest 3 pieces of content regardless of which model they belong to.

With (psuedo) sql I could do something like:

SELECT * 
FROM blog, news, photo, 
WHERE is_published=True
ORDER by publication_date
LIMIT 3  

I don't really want to use to use raw sql in Django as i want a query set returned, so is there a way I can make this type of query with Django?

Thanks,

Answer 1

If the 3 models are similar in some way (as they appear to be), the way I would probably do it is by creating a base model and then have the 3 other models inherit from that model.

class Publishable(models.Model):
    is_published = models.BooleanField(default=False)
    publication_date = models.DatetimeField()
    ... other fields ...

class Blog(Publishable):
   ...extra fields...

class News(Publishable):
   ...extra fields...

class Photos(Publishable):
   ...extra fields...

Then later on, you can do:

Publishable.objects.order_by('-publication_date')[:3]

If you still need the "type" associated with the retrieved models, check out the Inheritance Manager

You'll probably want to read about the pros and cons about Model Inheritance as well.