Django: accessing the related_name on a Model returns None

December 18, 2022

models.py

from django.contrib.auth.models import AbstractUser
from django.db import models


class User(AbstractUser):
    pass

class Likes(models.Model):
    pass

class Unlikes(models.Model):
    pass

class Post(models.Model):
    post_text = models.TextField(max_length=1000)
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='posts')
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    likes = models.ManyToManyField(User, null=True, related_name="liked_posts")
    unlikes = models.ManyToManyField(User, null=True, related_name="unliked_posts")

    def __str__(self):
        return f'{self.user} at {self.created_at}: {self.post_text[0:20]}...'

views.py

def profile(request, username):
    print(User.objects.get(username=username).posts)
    print(Post.objects.filter(user = User.objects.get(username=username)))
    return render(request, 'network/profile.html', {
        'user': request.user,
        'profile': User.objects.get(username=username)
    })

My models.py file defines the relationship between User and post as follows:

user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='posts')

Running:

print(User.objects.get(username=username).posts)
print(Post.objects.filter(user = User.objects.get(username=username)))

returns:

network.Post.None
<QuerySet [<Post: Joe at 2022-12-18 10:48:18.941880+00:00: test1...>, <Post: Joe at 2022-12-18 10:53:27.407349+00:00: test1...>, <Post: Joe at 2022-12-18 10:53:34.167508+00:00: test2...>]>

My question:
How can the first print statement return no rows, when the second statement returns the expected value (3 rows)? As far as I understand, the two statements should achieve the same thing?

>Solution :

.posts is a Manager, not a QuerySet, you can use .all() [Django-doc], to turn it into a QuerySet:

from django.contrib.auth.decorators import login_required


@login_required
def profile(request, username):
    print(User.objects.get(username=username).posts.all())
    print(Post.objects.filter(user=User.objects.get(username=username)))
    return render(
        request,
        'network/profile.html',
        {'user': request.user, 'profile': User.objects.get(username=username)},
    )