过滤Django管理员Null /不是空

Question

我有一个简单的Django模型,如:

class Person(models.Model):
    referrer = models.ForeignKey('self', null=True)
    ...

在这个模型的ModelAdmin中,我如何通过referrer是否为null来过滤它？默认情况下,将referrer添加到list_filter会导致显示一个下拉列表,其中列出了可能数十万的每个人的记录,从而有效地阻止了页面的加载.即使它加载,我仍然无法按照我想要的标准进行过滤.

即如何修改此选项,以便下拉列表仅列出"全部","空"或"非空"选项？

我已经看过一些声称使用自定义FilterSpec子类完成类似操作的帖子,但它们都没有解释如何使用它们.我见过的少数似乎适用于所有型号的所有领域,我不想要.此外,FilterSpec 没有文档,这让我感到紧张,因为我不想投入大量自定义代码,这些代码与一些可能在下一版本中消失的瞬态内部类相关联.

Answer 1

由于Django 1.4对过滤器进行了一些更改,我认为我节省了一些时间,因为我只是修改了Cerin接受的使用Django 1.4 rc1的答案的代码.

我有一个名为"已启动"的TimeField(null = True)的模型,我想过滤掉null和非null值,因此它与OP的问题大致相同.
那么,这对我有用...

在admin.py中定义(实际包含)这些:

from django.contrib.admin.filters import SimpleListFilter

class NullFilterSpec(SimpleListFilter):
    title = u''

    parameter_name = u''

    def lookups(self, request, model_admin):
        return (
            ('1', _('Has value'), ),
            ('0', _('None'), ),
        )

    def queryset(self, request, queryset):
        kwargs = {
        '%s'%self.parameter_name : None,
        }
        if self.value() == '0':
            return queryset.filter(**kwargs)
        if self.value() == '1':
            return queryset.exclude(**kwargs)
        return queryset



class StartNullFilterSpec(NullFilterSpec):
    title = u'Started'
    parameter_name = u'started'

而不仅仅是在ModelAdmin中使用它们:

class SomeModelAdmin(admin.ModelAdmin):
    list_filter =  (StartNullFilterSpec, )

Answer 2

在 Django 3.1 之后，您可以使用EmptyFieldListFilter：

class MyAdmin(admin.ModelAdmin):
    list_filter =  (
        ("model_field", admin.EmptyFieldListFilter),
    )

Answer 3

我有一个简单版本的frnhr的答案,它实际上是在__isnull条件上过滤的.(Django 1.4+):

from django.contrib.admin import SimpleListFilter

class NullListFilter(SimpleListFilter):
    def lookups(self, request, model_admin):
        return (
            ('1', 'Null', ),
            ('0', '!= Null', ),
        )

    def queryset(self, request, queryset):
        if self.value() in ('0', '1'):
            kwargs = { '{0}__isnull'.format(self.parameter_name) : self.value() == '1' }
            return queryset.filter(**kwargs)
        return queryset

然后还:

class StartNullListFilter(NullListFilter):
    title = u'Started'
    parameter_name = u'started'

最后:

class SomeModelAdmin(admin.ModelAdmin):
    list_filter =  (StartNullListFilter, )

我个人不喜欢把我的垃圾admin.py分成几十个类,所以我想出了这样一个帮助函数:

def null_filter(field, title_=None):
    class NullListFieldFilter(NullListFilter):
        parameter_name = field
        title = title_ or parameter_name
    return NullListFieldFilter

我可以在以后申请:

class OtherModelAdmin(admin.ModelAdmin):
    list_filter =  (null_filter('somefield'), null_filter('ugly_field', _('Beautiful Name')), )

Answer 4

有一个简单的方法：

class RefererFilter(admin.SimpleListFilter):
    title = 'has referer'
    # Parameter for the filter that will be used in the URL query.
    parameter_name = 'referer__isnull'

    def lookups(self, request, model_admin):
        return (
            ('False', 'has referer'),
            ('True', 'has no referer'),
        )

    def queryset(self, request, queryset):
        if self.value() == 'False':
            return queryset.filter(referer__isnull=False)
        if self.value() == 'True':
            return queryset.filter(referer__isnull=True)

然后在 ModelAdmin 中使用它们：

class PersonAdmin(admin.ModelAdmin):
    list_filter =  (RefererFilter,) 

Answer 5

我最终使用了这里的顶级解决方案以及此代码片段的混合物。

然而，我不得不稍微调整一下代码片段，删除字段类型限制并添加新的 field_path（最近在 1.3 中添加）。

from django.contrib.admin.filterspecs import FilterSpec
from django.db import models
from django.utils.safestring import mark_safe
from django.utils.translation import ugettext as _

class NullFilterSpec(FilterSpec):
    #fields = (models.CharField, models.IntegerField, models.FileField)

    @classmethod
    def test(cls, field):
        #return field.null and isinstance(field, cls.fields) and not field._choices
        return field.null and not field._choices
    #test = classmethod(test)

    def __init__(self, f, request, params, model, model_admin, field_path=None):
        super(NullFilterSpec, self).__init__(f, request, params, model, model_admin, field_path)
        self.lookup_kwarg = '%s__isnull' % f.name
        self.lookup_val = request.GET.get(self.lookup_kwarg, None)

    def choices(self, cl):
        # bool(v) must be False for IS NOT NULL and True for IS NULL, but can only be a string
        for k, v in ((_('All'), None), (_('Has value'), ''), (_('Omitted'), '1')):
            yield {
                'selected' : self.lookup_val == v,
                'query_string' : cl.get_query_string({self.lookup_kwarg : v}),
                'display' : k
            }

# Here, we insert the new FilterSpec at the first position, to be sure
# it gets picked up before any other
FilterSpec.filter_specs.insert(0,
    # If the field has a `profilecountry_filter` attribute set to True
    # the this FilterSpec will be used
    (lambda f: getattr(f, 'isnull_filter', False), NullFilterSpec)
)