Django join on multiple foreign fields (left join) - django

Question

I'm using django 1.10 and have the following two models
class Post(models.Model):
title = models.CharField(max_length=500)
text = models.TextField()
class UserPost(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
post = models.ForeignKey(Post, on_delete=models.CASCADE)
approved = models.BooleanField(default=False)
How do I get a list of all the posts including the 'approved' property for the logged in user if exists? So instead of multiple queries, it would be one left join query, pseudo-code:
select * from posts as p
left join user_posts as up
on up.post_id = p.post_id
and up.user_id = 2
Output
post_id | title | text | user_id | approved
1 | 'abc' | 'abc' | 2 | true
2 | 'xyz' | 'xyz' | null | null
3 | 'foo' | 'bar' | 2 | true
I created the models this way because the 'approved' property belongs to the user. Every user can approve/reject a post. The same post could be approved and rejected by other users. Should the models be setup differently?
Thanks
Update:
I'm trying to create a webpage to display all available posts and highlight the ones that the current user approved. I could just list all posts and then for each post check if the 'UserPost' table has a value, if yes get the approved property else ignore. But that means if I have 100 posts I'm making 100 + 1 calls to the db. Is it possible to do 1 call using ORM? If this is not possible, should the models be setup differently?

Answer 1

Then I think you need something like this:
Post.objects.all().annotate(
approved=models.Case(
models.When(userpost_set__user_id=2,
then=models.F('userpost__approved')),
default=models.Value(False),
output_field=models.BooleanField()
)
)