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django过滤器与空字段混淆

django-filter django python

Antoine Pinsard · 技术社区 · 6 年前

django-filter 筛选我的一些列表。以下是其中一个,带有自定义窗体:

class BookingListFiltersForm(forms.Form):

    state__in = forms.MultipleChoiceField(
        choices=Booking.STATE_CHOICES, required=False,
        label=_("Ãtat"), 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})

表单是通过GET方法提交的。当字段“source\uu in”为空时,querystring看起来像“?state\uu in=1”。在这种情况下,我的页面中没有结果(这是出乎意料的,如果没有填写某个字段,我希望结果不会在此字段上过滤)。

我查看了debug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,我没有找到相关查询集的SQL查询(如果querystring为“”,则state\uu in=1&例如,结果与预期一致,我可以在调试工具栏中找到相关查询)

所以我尝试使用 print(str(filters.qs.query)) . 新的惊喜,这引发了 EmptyResultSet 例外情况:

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。

另外,这里是相关的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()

以及视图类 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,您有完整的继承树,请注意 ListView utils.views.manager.ListView :

class ListView(BulkActionsMixin, ManagerMixin, BaseListView):
    pass

以及 BaseListView utils.views.common.ListView :

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

最后 基本列表视图 是 django.views.generic.list.ListView .

ipdb

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>

所以接下来的代码 source__in source__in=empty_queryset 到过滤器。我猜django然后猜测结果不能计算为非空查询集,并保存一个无用的查询。

django-filters 还是我做错了什么?

2 回复 | 直到 6 年前

Kamil Niski 6 年前

我认为文档回答了你的问题:

Filtering by an empty string

值被解释为跳过的筛选器。
GET http://localhost/api/my-model?myfield=

在文档中,您还可以看到可能的解决方案示例。我把其中一个放在这里

解决方案1:神奇的价值观

可以重写filter类的filter()方法检查魔法值。这类似于ChoiceFilters null 价值处理。

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

现在我觉得没有足够的信息来解决你的问题。我在你的问题下留言了。如果你能提供额外的信息,这将大大有助于了解正在发生的事情。

以下是一些可以帮助您跟踪此错误的提示:

安装 ipdb

删除断点 import ipdb;ipdb.set_trace() 行前

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

我想你应该在监狱里找到罪犯 https://github.com/carltongibson/django-filter/blob/82a47fb7bbddedf179f110723003f3b28682d7fe/django_filters/filterset.py#L215

你可以这样做

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):

Antoine Pinsard 6 年前

我终于弄明白了问题所在。

django-filters in 外键。的默认筛选器 source__in 例如,是 ModelChoiceFilter ModelMultipleChoiceFilter .

source__in=10&source__in=7 大致翻译成 Q(source__in=10) | Q(source__in=7) . 这是一个例外,因为10和7是不可数的。所以我把代码改成了 exact 查找而不是 在里面 模型多重回声滤波器 . 最后,得出以下结论:

class BookingListFiltersForm(forms.Form):

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


class BookingManagerFilter(filters.FilterSet):

    source = filters.ModelMultipleChoiceFilter(
        queryset=Platform.objects.all())
    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': ['exact'],
            'booking_date': ['date', 'date__lte', 'date__gte'],
            'accommodation': ['exact'],
            'guest': ['exact']
        }

    def get_form_class(self):
        return BookingListFiltersForm