如何在 Django 中为外键字段使用 django-filter 包？

Question

大家好！

Django 中的新手，很困惑，感谢帮助！感谢stackoverflow用户，我创建了一个表，例如：

Organization	Total amount of appeals	Amount of written form appeals	Amount of oral form appeals
Organization 1	3	1	2
Organization 2	2	1	1

拥有三个模型：

class Organization(models.Model):
    organization_name = models.CharField(max_length=50)


class AppealForm(models.Model):
    form_name = models.CharField(max_length=50)


class Appeal(models.Model):
    organization = models.ForeignKey(Organization, on_delete=models.CASCADE)
    appeal_form = models.ForeignKey(AppealForm, on_delete=models.CASCADE)
    applicant_name = models.CharField(max_length=150)
    appeal_date = models.DateField()

组织模型的对象：

organization_name
Organization 1
Organization 2

AppealForm模型的对象：

form_name
In written form
In oral form

上诉模型的对象：

organization	appeal_form	applicant_name
Organization 1	In written form	First and Last name
Organization 1	In oral form	First and Last name
Organization 1	In oral form	First and Last name
Organization 2	In written form	First and Last name
Organization 2	In oral form	First and Last name

在 views.py 文件的函数中，我创建了一个查询来呈现，例如：

from django.db.models import Count, Q

organizations = Organization.objects.annotate(
).annotate(
    total=Count('appeal'),
    total_written=Count('appeal', filter=Q(appeal__appeal_form__form_name='in written form')),
    total_oral=Count('appeal', filter=Q('appeal__appeal_form__form_name='in oral form'))
)

现在我想按 AppealForm 模型和上诉日期（Appeal_date Appeal_date 字段）过滤表格内容。案例：用户打开一个表格，然后从表格上方的搜索栏中选择要查看的申诉表和/或日期范围。

问题：如何使用django-filter包过滤views.py上面的查询？

Answer 1

定义复杂过滤器的最通用方法是使用方法参数。我不能说我完全理解你的问题，但是你可以应用任何你可以通过这种方式设计查询集的过滤器。概述：

import django-filters as DF

class SomeFilters( DF.FilterSet):

    name = DF.xxxFilter( method='my_method', field_name='object_field', label='whatever',  ...)
    ...

    def my_method( self, qs, name, value):
        # in here you create a new more restrictive queryset based on qs
        # to implement your filter, and return it.
        # name is the field name. Note, you don't have to use or follow it
        # value is the value that the user typed

        qs = qs.filter( ...) # or .exclude, or complicated stuff  
        return qs

这是我编写的一个相当简单的方法，用于创建一个带有去掉空格的字段值的注释，然后对其进行文本包含过滤器。

    def filter_array_desc( self, qs, name, value):
        value = value.replace(' ','')
        qs = qs.annotate(
            arr_d_nospaces = Replace( 'array_desc', Value(' '), Value('')) # delete all spaces
        ).filter(
            arr_d_nospaces__icontains = value )
        return qs

这是一个通用的，可以通过ChoiceFilter 应用于任何字段以过滤该字段是否为空白：

    YESNO = (('Y','Yes'), ('N','No'))
    marr_b = FD.ChoiceFilter( field_name='marr', label='M_array is blank',  method='filter_blank_yesno', 
                              choices=YESNO, empty_label="Don't Care" )
    ...

    def filter_blank_yesno( self, qs, name, value):
        if value=="Y":
            return qs.filter(**{ name:'' })
        elif value=="N":
            return qs.exclude( **{ name:'' })
        raise ValueError(f'filter_blank_yesno received value="{value}" which is neither "Y" nor "N"')

希望这会有所帮助。您基本上将通过遵循模型之间的关系进行过滤，使用双下划线在模型之间移动，并可能对注释进行注释和过滤，或者使用 Q 对象等进行操作。