Question

Users can upload three different types of content onto our site: image, video, audio. Here are the models for each type:

class ImageItem(models.Model):
    user = models.ForeignKey(User)
    upload_date = models.DateTimeField(auto_now_add=True)
    image = models.ImageField(upload_to=img_get_file_path)
    title = models.CharFiled(max_length=1000,
                             blank=True)

class VideoItem(models.Model):
    user = models.ForeignKey(User)
    upload_date = models.DateTimeField(auto_now_add=True)
    video = models.FileField(upload_to=vid_get_file_path)
    title = models.CharFiled(max_length=1000,
                             blank=True)

class AudioItem(models.Model):
    user = models.ForeignKey(User)
    upload_date = models.DateTimeField(auto_now_add=True)
    audio = models.FileField(upload_to=aud_get_file_path)
    title = models.CharFiled(max_length=1000,
                             blank=True)

I have a page called library.html, which renders all the items that a user has uploaded, in order from most recently uploaded to oldest uploads (it displays the title and upload_date of each instance, and puts a little icon on the left symbolizing what kind of item it is).

Assuming it requires three separate queries, how can I merge the three querysets? How can I make sure they are in order from most recently uploaded?

Answer 1

Referencing the question, this is the exact solution I used. Influenced by monkut’s answer and the top answer from Frantzdy’s link in his comment (thanks guys).

from itertools import chain
from operator import attrgetter

images = ImageItem.objects.filter(user=user)
video = VideoItem.objects.filter(user=user)
audio = AudioItem.objects.filter(user=user)
result_list = sorted(chain(images, video, audio),
                     key=attrgetter('upload_date'),
                     reverse=True)