How Do I Collect Multiple Django Models Together Into A Single List?
I have a fairly straightforward blog in Django, with separate models for Article and Link. I want to have a loop in my template that lists them both in date order, which means some
Solution 1:
Turns out the solution is to turn the abstract class into a real one, and then I can collect over that.
Solution 2:
Well, the obvious answer would have been to make Post a concrete class. Else you'll probably have to squeeze the ORM and resort to handcoded SQL or manually merge/order your two querysets. Given the small size of the dataset, I'd go for this last solution.
Solution 3:
Refactoring could be the better solution, but here is another one that could do the job:
Create a custom Manager:
classPostManager(models.Manager):
defmixed(self, first):
all_dates = []
articles_dates = Articles.objects.extra(select={'type':'"article"'}).values('id', 'post_date', 'type').order_by('-post_date')[:first]
links_dates = Links.objects.extra(select={'type':'"link"'}).values('id', 'post_date', 'type').order_by('-post_date')[:first]
all_dates.extend(articles_dates)
all_dates.extend(links_dates)
# Sort the mixed list by post_date, reversed
all_dates.sort(key=lambda item: item['post_date'], reverse=True)
# Cut first 'first' items in mixed list
all_dates = all_dates[:first]
mixed_objects = []
mixed_objects.extend(Articles.objects.filter(id__in=[item['id'] for item in all_dates if item['type'] = 'article']))
mixed_objects.extend(Links.objects.filter(id__in=[item['id'] for item in all_dates if item['type'] = 'link']))
# Sort again the result list
mixed_objects.sort(key=lambda post: post.post_date, reverse=True)
return mixed_objects
And use it in your abstract model:
classPost(models.Model):
classMeta:
abstract = Trueobjects= PostManager()
Then the call for your mixed objects will be:
Article.objects.mixed(10)
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