Question

我正在运行django 2.1.7，DRF并使用taggit。我正在编写自己的自定义查询集来查找对象具有的标签。网址： example.com/api/tags=书，耳机，睡眠

应返回JSON，该JSON的对象顺序为：从包含大多数标签到包含至少一个标签。这是gitgist

from django.db.models import Case, ExpressionWrapper, IntegerField, Q, Value, When

class SpecialSearch(ListAPIView):
    model = Object
    serializer_class = ObjectSerializer

    def get_queryset(self, rs, value):
        """
        Recipe search matching, best matching and kind of matching,
        by filtering against `tags` query parameter in the URL.
        """
        if value:
            tags = [tag.strip() for tag in value.split(',')]
            qs = Object.objects.filter(
                reduce(
                    lambda x, y: x | y, [Q(tags__icontains=tag) for tag in tags]))
            check_matches = map(
                lambda x: Case(
                    When(Q(tags__icontains=x), then=Value(1)),
                        default=Value(0)),
            tags)
            count_matches = reduce(lambda x, y: x + y, check_matches)
            qs = qs.annotate(
            matches=ExpressionWrapper(
                count_matches,
                output_field=IntegerField()))
            qs = qs.order_by('-matches')
        return qs

当前，此代码我提交了一些作品，但是在提交一系列新标签时，返回的是由对象ID和API端点排序的json，不会从API接收到新的json转储。我现在完全迷路了。任何帮助将不胜感激。

Answer 1

对于OP来说可能为时已晚，但是如果有人看了这个，在count_matches周围添加Sum（）可能会成功：

from django.db.models import (Case, ExpressionWrapper, IntegerField, Q, Value, When, Sum)

class SpecialSearch(ListAPIView):
    model = Object
    serializer_class = ObjectSerializer

    def get_queryset(self, rs, value):
        """
        Recipe search matching, best matching and kind of matching,
        by filtering against `tags` query parameter in the URL.
        """
        if value:
            tags = [tag.strip() for tag in value.split(',')]
            qs = Object.objects.filter(
                reduce(
                    lambda x, y: x | y, [Q(tags__icontains=tag) for tag in tags]))
            check_matches = map(
                lambda x: Case(
                    When(Q(tags__icontains=x), then=Value(1)),
                        default=Value(0)),
            tags)
            count_matches = reduce(lambda x, y: x + y, check_matches)
            qs = qs.annotate(
            matches=ExpressionWrapper(
                Sum(count_matches),
                output_field=IntegerField()))
            qs = qs.order_by('-matches')
        return qs

无法获取查询集以返回按标签匹配降序的对象列表

1 个答案: