I have a task where I need to get stats and feedback by moderator ID. The 'stats' field is general, the 'feedback' field is a list of feedbacks. Can I make pagination for 'feedback' field? Of course I can make different endpoints for stats and feedback, but I'm not allowed to do this.

// GET /api/moderators/:id/feedback
{
    "stats": [
        {
            "name": "123",
            "value": -10
        }
    ],
    "feedback": [
        {
            "id": 1,
            "createdBy": "FN LN",
            "createdAt": "DT",
            "comment": "",
            "score": 5,
            "categories": [
                {
                    "name": "123",
                    "status": "POSITIVE/NEGETIVE/UNSET"
                }
            ],
            "webinarID": 123456
        },
        {
            ...
        }
        
    ]
}

views.py

class TeacherFeedbackViewSet(ViewSet):
    permission_classes = [IsAuthenticated, TeacherFeedbackPerm]
    renderer_classes = [CamelCaseJSONRenderer]

    @base_view
    def list(self, request, pk):
        moderator = get_object_or_404(Moderator, pk=pk)
        serializer = ModeratorFeedback(moderator)
        return Response(serializer.data)

serializers.py

class TeacherFeedbackSerializerDetail(ModelSerializer):
    created_at = DateTimeField(source='datetime_filled')
    created_by = SerializerMethodField(method_name='get_created_by')
    categories = SerializerMethodField(method_name='get_categories')
    webinar_id = IntegerField(source='webinar.id')
    moderator_id = IntegerField(source='moderator.id')

    class Meta:
        model = TeacherFeedback
        fields = ['id', 'created_by', 'created_at', 'categories', 'score', 'comment', 'moderator_id', 'webinar_id']

    def get_categories(self, feedback: TeacherFeedback):
        data = []
        category_names = list(FeedbackCategory.objects.all().values_list('name', flat=True))
        for category in feedback.category.all():
            z = TeacherFeedbackCategory.objects.get(category=category, feedback=feedback)
            data.append({"name": z.category.name, "status": z.status})

        unset = list(map(lambda x: {"name": x, "status": "unset"},
                         list(set(category_names) - set([i["name"] for i in data]))))
        return sorted(data   unset, key=lambda x: x["status"])

    def get_created_by(self, feedback: TeacherFeedback):
        return str(feedback.created_by.teacher)


class ModeratorFeedback(serializers.ModelSerializer):
    stats = serializers.SerializerMethodField(method_name='get_stats_list')
    feedback = TeacherFeedbackSerializerDetail(many=True, source='actual_feedbacks')

    class Meta:
        model = Moderator
        fields = ['stats', 'feedback']

    def get_stats_list(self, moderator: Moderator):
        data = {}
        for feedback in moderator.actual_feedbacks:
            for category in feedback.category.all():
                category_detail = TeacherFeedbackCategory.objects.get(feedback=feedback, category=category)
                if category.name not in data:
                    data[category.name] = [category_detail.status]
                else:
                    data[category.name].append(category_detail.status)
        stats = []
        for k, statuses in data.items():
            weight = 100/len(statuses)
            current_value = 0
            for status in statuses:
                if status == 'positive':
                    current_value  = weight
                else:
                    current_value -= weight
            stats.append({"name": k, "value": float("{0:.2f}".format(current_value))})
        return stats

CodePudding user response：

In order to realize the pagination here, you need to make serializer for stats and feedback data respectively.

First you can define the ModeratorStats serializer.

class ModeratorStats(serializers.ModelSerializer):
    stats = serializers.SerializerMethodField(method_name='get_stats_list')

    class Meta:
        model = Moderator
        fields = ['stats']

    def get_stats_list(self, moderator: Moderator):
        ...

And TeacherFeedbackSerializerDetail serializer is for the feedback. Now in view,

from django.core.paginator import Paginator
from rest_framework.response import Response

class TeacherFeedbackViewSet(ViewSet):
    ...

    @base_view
    def list(self, request, pk):
        moderator = get_object_or_404(Moderator, pk=pk)

        # first get page and size param
        page = int(request.GET.get('page', "1"))
        size = int(request.GET.get('size', "10"))
       
        # here I assumed the foreign key field name is `moderator`
        query_set = TeacherFeedback.objects.filter(moderator__id = pk)
        paginator = Paginator(query_set.order_by('id'), size)
        feedbacks = paginator.page(page)
        
        stats_data = ModeratorStats(moderator).data
        feedbacks = TeacherFeedbackSerializerDetail(feedbacks, many=True).data
        
        return Response({"stats": stats_data, "feedback": feedbacks})

And in frontend, you need to upload pagination params like ...?page=1&size=10.