如何序列化对象列表？

Question

The Django-Rest-Framework documentation ( https://www.django-rest-framework.org/api-guide/serializers/ ) gives the following example for serializing a list of objects:

queryset = Book.objects.all()
serializer = BookSerializer(queryset, many=True)
serializer.data

I try to do something similar with the following code:

@api_view(['GET'])
def postComments(request, pk):
    """
    Retrieve all comments with originalPostId = pk.
    """
    if request.method == 'GET':
        comments = Comment.objects.all()
        comments = comments.filter(originalPostId = pk)
        serializer = CommentSerializer(comments, many=True)
        if serializer.is_valid():
            return Response(serializer.data)
        logger.error(serializer.errors)

However, right off the bat I get the following error: AssertionError: Cannot call `.is_valid()` as no `data=` keyword argument was passed when instantiating the serializer instance.

This other post ( django-rest-framework: Cannot call `.is_valid()` as no `data=` keyword argument was passed when instantiating the serializer instance ) seems to address this, but the answer suggests that putting in data= when calling my CommentSerializer would serve to deserialize instead of serialize, which is not what I want.

However, when I do run with the line serializer = CommentSerializer(data=comments, many=True) I get the error {'non_field_errors': [ErrorDetail(string='Expected a list of items but got type "QuerySet".', code='not_a_list')]}

Here is my serializer, in case that matters:

    poster = UserSerializer()
    community = CommunitySerializer()
    originalPost = PostSerializer()
    class Meta:
        model = Comment
        fields = ['post', 'community', 'poster', 'originalPost', 'originalPostId']

    def create(self, validated_data):
        userData = validated_data.pop('poster')
        user = User.objects.get_or_create(username=userData['username'],
                                                       email=userData['email'],
                                                       first_name=userData['first_name'],
                                                       last_name=userData['last_name'],
                                                       password=userData['password'])[0]
        validated_data['poster'] = user
        communityData = validated_data.pop('community')
        community = Community.objects.get_or_create(name=communityData['name'])[0]
        validated_data['community'] = community

        originalPostData = validated_data.pop('originalPost')
        originalPost = Post.objects.get_or_create(id = validated_data['originalPostId'])[0]
        validated_data['originalPost'] = originalPost

        comment = Comment.objects.create(**validated_data)
        return comment```

Answer 1

@api_view(['GET'])
def postComments(request, pk):
    """
    Retrieve all comments with originalPostId = pk.
    """
    if request.method == 'GET':
        comments = Comment.objects.all()
        comments = comments.filter(originalPostId = pk)
        serializer = CommentSerializer(comments, many=True)
        return Response(serializer.data)

Getting rid of the is_valid() check made it work. I guess I just needed to believe in myself~

Answer 2

is_valid is used for the validating user input data, so no need of call is_valid.

@api_view(['GET'])
def postComments(request, pk):
    """
    Retrieve all comments with originalPostId = pk.
    """
    if request.method == 'GET':
        comments = Comment.objects.filter(originalPostId = pk).all()
        serializer = CommentSerializer(comments, many=True)
        return Response(serializer.data)