如何在Django中优先搜索？

问题描述

我在MysqL数据库中使用djangorestframework。 我有一个视图，该视图根据搜索查询参数返回一个列表。 我正在使用rest_frameworks.filters SearchFilter进行基于搜索的过滤。 这是我的观点：

from rest_framework import filters
from rest_framework.generics import ListAPIView
...

class FooListView(ListAPIView):
    serializer_class = SymbolSerializer
    queryset = Symbol.objects.all()
    filter_backends = [filters.SearchFilter]
    search_fields = ['field_A','field_B','field_C']

要调用的示例网址是：

http://localhost:8000/symbols/symbols/?search=bird

现在一切正常，但是我需要一个过滤器功能。SearchFilter不支持。 我希望我的搜索按search_fields的优先级排序。

例如，这里有两个记录：

foo1：{“ field_A”：“ any”，“ field_B”：“ many”，“ field_C”：“ bar”，“ id”：3}

foo2：{“ field_A”：“许多”，“ field_B”：“任何”，“ field_C”：“ bar”，“ id”：4}

现在，当我使用search = 'many'参数进行搜索时，我希望视图向我返回一个列表，其中foo2记录高于foo1（例如[foo2，foo1]），因为我希望搜索的优先级为field_A成绩，但它只返回一个按ID（[foo1，foo2]）排序的列表。

有帮助吗？

解决方法

我刚偶然遇到了同样的问题。

我的解决方案是使用this response的启发来稍微调整DRF filters.SearchFilter的搜索逻辑，最后得到以下定制过滤器类：

class PriorizedSearchFilter(filters.SearchFilter):
    def filter_queryset(self,request,queryset,view):
        """Override to return priorized results."""
        # Copy paste from DRF
        search_fields = getattr(view,'search_fields',None)
        search_terms = self.get_search_terms(request)

        if not search_fields or not search_terms:
            return queryset

        orm_lookups = [
            self.construct_search(six.text_type(search_field))
            for search_field in search_fields
        ]
        base = queryset
        conditions = []

        # Will contain a queryset for each search term
        querysets = list()

        for search_term in search_terms:
            queries = [
                models.Q(**{orm_lookup: search_term})
                for orm_lookup in orm_lookups
            ]

            # Conditions for annotated priority value. Priority == inverse of the search field's index.
            # Example: 
            #   search_fields = ['field_A','field_B','field_C']
            #   Priorities are field_A = 2,field_B = 1,field_C = 0
            when_conditions = [models.When(queries[i],then=models.Value(len(queries) - i - 1)) for i in range(len(queries))]
            
            # Generate queryset result for this search term,with annotated priority
            querysets.append(
                queryset.filter(reduce(operator.or_,queries))
                    .annotate(priority=models.Case(
                        *when_conditions,output_field=models.IntegerField(),default=models.Value(-1)) # Lowest possible priority
                    )
                )

        # Intersect all querysets and order by highest priority
        queryset = reduce(operator.and_,querysets).order_by('-priority')

        # Copy paste from DRF
        if self.must_call_distinct(queryset,search_fields):
            # Filtering against a many-to-many field requires us to
            # call queryset.distinct() in order to avoid duplicate items
            # in the resulting queryset.
            # We try to avoid this if possible,for performance reasons.
            queryset = distinct(queryset,base)
        return queryset

使用filter_backends = [PrioritizedSearchFilter]，您已设置好。