django-filter用空场乱搞

Question

我设置了django-filter来过滤我的一些列表.以下是其中一个,具有自定义形式:

class BookingListFiltersForm(forms.Form):

    state__in = forms.MultipleChoiceField(
        choices=Booking.STATE_CHOICES, required=False,
        label=_("État"), widget=forms.CheckboxSelectMultiple)
    source__in = forms.ModelMultipleChoiceField(
        queryset=Platform.objects.all(), required=False,
        label=_("Source"), widget=ModelSelect2Multiple(
            url='autocomplete:platform'))


class BookingManagerFilter(filters.FilterSet):

    payments__date = filters.DateFilter(method='payments__date_filter')
    payments__method = filters.ChoiceFilter(
        method='payments__method_filter',
        choices=BookingPayment.METHOD_CHOICES,
    )

    class Meta:
        model = Booking
        fields = {
            'period': [
                'endswith', 'endswith__gte', 'endswith__lte',
                'startswith', 'startswith__gte', 'startswith__lte',
            ],
            'state': ['in'],
            'source': ['in'],
            'booking_date': ['date', 'date__lte', 'date__gte'],
            'accommodation': ['in'],
            'guest': ['exact']
        }

    def get_form_class(self):
        return BookingListFiltersForm

    def payments__date_filter(self, queryset, name, value):
        return queryset.filter(**{name: value})

    def payments__method_filter(self, queryset, name, value):
        return queryset.filter(**{name: value})

表格由GET方法提交.当字段"source__in"为空时,查询字符串看起来像"？state__in = 1".在这种情况下,我的页面没有结果(这是意料之外的,如果没有填写字段,我希望结果不会在此字段上过滤).

我查看了调试工具栏,以获得有关已执行SQL查询的更多信息.令人惊讶的是,我发现相关查询集没有SQL查询!(例如,如果查询字符串是"？state__in = 1&source__in = 2",结果是预期的,我可以在调试工具栏中找到相关的查询)

所以我试图强制使用SQL查询的印象print(str(filters.qs.query)).新的惊喜,这引发了一个EmptyResultSet例外:

Traceback:

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  35.             response = get_response(request)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  128.                 response = self.process_exception_by_middleware(e, request)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  126.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/views/generic/base.py" in view
  69.             return self.dispatch(request, *args, **kwargs)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/utils/decorators.py" in _wrapper
  62.             return bound_func(*args, **kwargs)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/contrib/auth/decorators.py" in _wrapped_view
  21.                 return view_func(request, *args, **kwargs)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/utils/decorators.py" in bound_func
  58.                 return func.__get__(self, type(self))(*args2, **kwargs2)

File "/home/tony/Workspace/cocoonr/utils/views/manager.py" in dispatch
  29.         return super().dispatch(*args, **kwargs)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/views/generic/base.py" in dispatch
  89.         return handler(request, *args, **kwargs)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/views/generic/list.py" in get
  142.         self.object_list = self.get_queryset()

File "/home/tony/Workspace/cocoonr/booking/views/manager.py" in get_queryset
  73.         queryset = super().get_queryset()

File "/home/tony/Workspace/cocoonr/utils/views/common.py" in get_queryset
  118.         print(self.filters.qs.query)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/db/models/sql/query.py" in __str__
  252.         sql, params = self.sql_with_params()

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/db/models/sql/query.py" in sql_with_params
  260.         return self.get_compiler(DEFAULT_DB_ALIAS).as_sql()

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/db/models/sql/compiler.py" in as_sql
  461.                 where, w_params = self.compile(self.where) if self.where is not None else ("", [])

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/db/models/sql/compiler.py" in compile
  393.             sql, params = node.as_sql(self, self.connection)

File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/db/models/sql/where.py" in as_sql
  98.                     raise EmptyResultSet

Exception Type: EmptyResultSet at /manager/booking/bookings/
Exception Value: 

现在我卡住了,我不知道出了什么问题以及如何进一步调试.

为了测试,我试图传递以下查询字符串:"？state__in = 1&source__in =".在这种情况下,过滤工作正常,但过滤器表单显示错误"«»不是"字段"source__in"的有效值".

另外,这里有相关的mixin utils/views/common.py:

class ListFilterMixin:

    filters_class = None
    default_filters = None

    @cached_property
    def filters(self):
        return self.get_filters()

    def get_filters(self):
        if self.filters_class:
            qstring = self.request.GET
            if not qstring and self.default_filters:
                qstring = QueryDict(self.default_filters)
            return self.filters_class(
                qstring, self.get_unfiltered_queryset(), request=self.request)
        else:
            return None

    def get_queryset(self):
        print(self.filters.qs.query)  # <--- Line 118
        # ...

    def get_unfiltered_queryset(self):
        return super().get_queryset()

并且视图类在booking/views/manager.py:

class BookingListView(ListView):
    """List of all bookings."""

    model = Booking
    default_filters = 'state__in=1'
    filters_class = BookingManagerFilter
    paginate_by = 30
    ordering = '-pk'

    def get_queryset(self):
        queryset = super().get_queryset()  # <--- Line 73
        # ...

另外,所以你有完整的继承树,请注意ListView上面使用的是utils.views.manager.ListView:

class ListView(BulkActionsMixin, ManagerMixin, BaseListView):
    pass

并且BaseListView是utils.views.common.ListView:

class ListView(ListFilterMixin, AgencyMixin, ContextMixin, BaseListView):
    pass

最后BaseListView是django.views.generic.list.ListView.

---

使用ipdb像Kamil建议的调试,我注意到一个奇怪的事情可能是这种行为的原因:

ipdb> next
> /home.tony/.venvs/cocoonr/lib/python3.6/site-packages/django_filters/filters.py(167)filter()
    166     def filter(self, qs, value):
--> 167         if value != self.null_value:
    168             return super().filter(qs, value)

ipdb> self.null_value
'null'
ipdb> value
<QuerySet []>
ipdb> self.field_name
'source'
ipdb> self.lookup_expr
'in'
ipdb> 

因此后续代码考虑source__in不为空并添加source__in=empty_queryset到过滤器.我猜django然后猜测结果不能评估为非空的查询集并保存无用的查询.

这是一个错误django-filters或我做错了什么？

Answer 1

我认为文档可以回答您的问题：

按空字符串过滤

目前无法通过空字符串进行过滤，因为空值被解释为跳过的过滤器。

GET http://localhost/api/my-model?myfield=

在文档中进一步，您有可能的解决方案的示例。我把其中之一放在这里

解决方案1：神奇的价值

您可以重写过滤器类的filter（）方法来专门检查魔术值。这类似于ChoiceFilter的空值处理。

GET http://localhost/api/my-model?myfield=EMPTY

class MyCharFilter(filters.CharFilter):
    empty_value = 'EMPTY'

    def filter(self, qs, value):
        if value != self.empty_value:
            return super(MyCharFilter, self).filter(qs, value)

        qs = self.get_method(qs)(**{'%s__%s' % (self.name, self.lookup_expr): ""})
        return qs.distinct() if self.distinct else qs

目前，我觉得没有足够的信息来解决您的问题。我在你的问题下发表了评论。如果您可以提供额外的信息，则将极大地帮助您了解发生了什么。

这里有一些技巧可以帮助您跟踪此错误：

• 安装ipdb。它会帮助您逐步执行代码并检查每个变量。

• import ipdb;ipdb.set_trace()在行前放置断点

  File "/home/tony/.venvs/cocoonr/lib/python3.6/site-packages/django/views/generic/list.py" in get
    142.         self.object_list = self.get_queryset()
  

我怀疑您应该在https://github.com/carltongibson/django-filter/blob/82a47fb7bbddedf179f110723003f3b28682d7fe/django_filters/filterset.py#L215中找到罪魁祸首

你可以做这样的事情

class BookingManagerFilter(filters.FilterSet):
    # your previous code here

    def filter_queryset(self, queryset):
        import ipdb;ipdb.set_trace()
        return super(BookingManagerFilter, self)filter_queryset(queryset):

并运行您的端点，ipdb将停止该应用程序，您将能够进入代码并进行检查。

Answer 2

我终于弄清楚了这个问题。

\n\n

显然django-filters没有正确处理in外键的查找。source__in例如，默认过滤器是ModelChoiceFilter。所以我必须将其明确定义为ModelMultipleChoiceFilter.

\n\n

然而，我遇到了另一个问题，即source__in=10&source__in=7大致翻译为Q(source__in=10) | Q(source__in=7). 这会引发异常，因为 10 和 7 不是可迭代的。所以我更改了代码以使用exact查找而不是in但仍然使用ModelMultipleChoiceFilter. 最后给出以下内容：

\n\n

class BookingListFiltersForm(forms.Form):\n\n    state__in = forms.MultipleChoiceField(\n        choices=Booking.STATE_CHOICES, required=False,\n        label=_("\xc3\x89tat"), widget=forms.CheckboxSelectMultiple)\n    source = forms.ModelMultipleChoiceField(\n        queryset=Platform.objects.all(), required=False,\n        label=_("Source"), widget=ModelSelect2Multiple(\n            url=\'autocomplete:platform\'))\n\n\nclass BookingManagerFilter(filters.FilterSet):\n\n    source = filters.ModelMultipleChoiceFilter(\n        queryset=Platform.objects.all())\n    payments__date = filters.DateFilter(method=\'payments__date_filter\')\n    payments__method = filters.ChoiceFilter(\n        method=\'payments__method_filter\',\n        choices=BookingPayment.METHOD_CHOICES,\n    )\n\n    class Meta:\n        model = Booking\n        fields = {\n            \'period\': [\n                \'endswith\', \'endswith__gte\', \'endswith__lte\',\n                \'startswith\', \'startswith__gte\', \'startswith__lte\',\n            ],\n            \'state\': [\'in\'],\n            \'source\': [\'exact\'],\n            \'booking_date\': [\'date\', \'date__lte\', \'date__gte\'],\n            \'accommodation\': [\'exact\'],\n            \'guest\': [\'exact\']\n        }\n\n    def get_form_class(self):\n        return BookingListFiltersForm\n

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