Django annotate M2M object with field from through model - django

Question

Let's say I have the following models:
class Color(models.Model):
name = models.CharField(max_length=255, unique=True)
users = models.ManyToManyField(User, through="UserColor", related_name="colors")
class UserColor(models.Model):
class Meta:
unique_together = (("user", "color"), ("user", "rank"))
user = models.ForeignKey(User, on_delete=models.CASCADE)
color = models.ForeignKey(Color, on_delete=models.CASCADE)
rank = models.PositiveSmallIntegerField()
I want to fetch all users from the database with their respective colors and color ranks. I know I can do this by traversing across the through model, which makes a total of 3 DB hits:
users = User.objects.prefetch_related(
Prefetch(
"usercolor_set",
queryset=UserColor.objects.order_by("rank").prefetch_related(
Prefetch("color", queryset=Color.objects.only("name"))
),
)
)
for user in users:
for usercolor in user.usercolor_set.all():
print(user, usercolor.color.name, usercolor.rank)
I discovered another way to do this by annotating the rank onto the Color objects, which makes sense because we have a unique constraint on user and color.
users = User.objects.prefetch_related(
Prefetch(
"colors",
queryset=(
Color.objects.annotate(rank=F("usercolor__rank"))
.order_by("rank")
.distinct()
),
)
)
for user in users:
for color in user.colors.all():
print(user, color, color.rank)
This approach comes with several benefits:
Makes only 2 DB hits instead of 3.
Don't have to deal with the through object, which I think is more intuitive.
However, it only works if I chain distinct() (otherwise I get duplicate objects) and I'm worried this may not be a legit approach (maybe I just came up with a hack that may not work in all cases).
So is the second solution legit? Is there a better way to it? Or should I stick to the first one?