Cannot query "object": Must be "User" instance - django

Question

I am creating sample-api which have posts and followers. Post should visible to followers only
My models.py
from django.contrib.auth.models import User
class Post(models.Model):
creator = models.ForeignKey(User, related_name='creator_post_set', null=True, on_delete=models.CASCADE)
title = models.CharField(max_length=25)
created_date = models.DateTimeField(auto_now_add=True)
content = models.TextField()
likes = models.BigIntegerField(null=True)
comments = models.BigIntegerField(null=True)
class Follow(models.Model):
follower = models.ForeignKey(User, related_name='following', null=True, on_delete=models.CASCADE)
followed_on = models.DateTimeField(auto_now_add=True)
following = models.ForeignKey(User, related_name='follower',null=True, on_delete=models.CASCADE)
My serializers.py for the models:
class UserSerializer(ModelSerializer):
password = serializers.CharField(write_only=True)
def create(self, validated_data):
user = User.objects.create_user(
username=validated_data['username'],
password=validated_data['password'],
first_name=validated_data['first_name'],
last_name=validated_data['last_name'],
)
return user
class Meta:
model = User
fields = ('password', 'username', 'first_name', 'last_name',)
class PostListSerializer(serializers.ModelSerializer):
class Meta:
model = Post
fields = ['title', 'content', 'created_date',]
class FollowSerializer(serializers.ModelSerializer):
class Meta:
model = Follow
fields = '__all__'
My views.py:
class PostList(generics.ListCreateAPIView):
serializer_class = PostListSerializer
follow_model = FollowSerializer.Meta.model
post_model = PostSerializer.Meta.model
def get_queryset(self):
try:
followers = self.follow_model.objects.get(follower_id =
self.request.user.id)
queryset = self.post_model.objects.get(creator__in = followers)
except self.follow_model.DoesNotExist:
queryset = None
return queryset
When I call this view it returns the following error:
Cannot query "Follow object (1)": Must be "User" instance.
I need help Thanks in Advance.

Answer 1

As I can see, Post model's creator is FKed to User model. So you need to query using User model instance, not Follower model.
You can use the following code:
following = self.request.user.following.all().values_list('follower', flat=True) # because of related name
queryset = self.post_model.objects.filter(creator_id__in = list(following))
Here I have first retrieved the user ids using self.request.following.all() by reverse relationship. Then I have extracted the user ids using values_list. After that, I have used it in Post.objects.filter(...) method.