在Django中自定义filter并在template中的使用详解

Django内置的filter有很多，然而我们由于业务逻辑的特殊要求，有时候仍然会不够用，这个时候就需要我们自定义filter来实现相应的内容。接下来让我们从自定义一个get_range(value)来产生列表的filter开始吧。

首先在你的django app的models.py的同级目录建立一个templatetags的文件夹，并在里面新建一个init.py的空文件，这个文件确保了这个文件夹被当做一个python的包。在添加了templatetags模块之后，我们需要重新启动服务器才能使其有效。

polls/
 __init__.py
 models.py
 templatetags/
   __init__.py
 views.py

然后在templatetags中新建一个python文件，文件名就是以后需要加载到页面的自定义库的名字。在这里我们新建一个generalfilters.py文件。

polls/
 __init__.py
 models.py
 templatetags/
   __init__.py
   generalfilters.py
 views.py

为了让库生效，必须在文件里添加一个模块级别的register变量。它是template.Library的实例，确保了标签和过滤器的有效性。

编辑generalfilters.py，添加

from django import template
register=template.Library()
@register.filter
def get_range(value):
 return range(value)

上述代码中定义了一个生成列表的函数，@register.filter表示这个函数是一个过滤器。至此我们的生成列表的过滤器就已经写好了。接下来我们需要把这个过滤器的库加载到模板里。

在你想要使用的模板的顶部加上{％ load generalfilters ％}，就可以使用这个过滤器了。

{％ for i in 5|get_range_bet_within ％}
 {{i}}
{％ endfor ％}

运行结果

补充知识：Django 自定义筛选器：重写DateFieldListFilter

我就废话不多说了，大家还是直接看代码吧！

class MyDateTimeFilter(admin.filters.DateFieldListFilter):
 def __init__(self, *args, **kwargs):
   super(MyDateTimeFilter, self).__init__(*args, **kwargs)

now = timezone.now()
   # When time zone support is enabled, convert "now" to the user's time
   # zone so Django's definition of "Today" matches what the user expects.
   if timezone.is_aware(now):
     now = timezone.localtime(now)

filter_end_date = now.replace(hour=0, minute=0, second=0, microsecond=0)

filter_start_date_for_one_week = filter_end_date - datetime.timedelta(days=7)

month_with_day31 = [1,3,5,7,8,10,12]
   if filter_end_date.month in month_with_day31 and filter_end_date.day == 31 and filter_end_date.month != 3:
     if filter_end_date.month == 1:
       filter_start_date_for_one_month = filter_end_date.replace(year=filter_end_date.year-1, month=12)
     else:
       filter_start_date_for_one_month = filter_end_date.replace(month=filter_end_date.month-1, day=30)
   elif filter_end_date.month == 3 and filter_end_date.day in [29, 30, 31]:
     if is_leap_year(filter_end_date.year):
       filter_start_date_for_one_month = filter_end_date.replace(month=filter_end_date.month-1, day=29)
     else:
       filter_start_date_for_one_month = filter_end_date.replace(month=filter_end_date.month-1, day=28)
   else:
     if filter_end_date.month == 1:
       filter_start_date_for_one_month = filter_end_date.replace(year=filter_end_date.year-1, month=12)
     else:
       filter_start_date_for_one_month = filter_end_date.replace(month=filter_end_date.month-1)

filter_start_date_for_six_month = ''
   filter_start_date_for_six_month_month = (filter_end_date.month - 6 + 12) ％ 12
   if filter_start_date_for_six_month_month == 0:
     filter_start_date_for_six_month_month = 12
   if filter_start_date_for_six_month_month in month_with_day31:
     if filter_end_date.month > 6:
       filter_start_date_for_six_month = filter_end_date.replace(month=filter_start_date_for_six_month_month)
     else:
       filter_start_date_for_six_month = filter_end_date.replace(year=filter_end_date.year-1, month=filter_start_date_for_six_month_month)
   elif filter_start_date_for_six_month_month == 2:
     if filter_end_date.day in [29, 30, 31]:
       if is_leap_year(filter_end_date.year):
         filter_start_date_for_six_month = filter_end_date.replace(month=filter_start_date_for_six_month_month, day=29)
       else:
         filter_start_date_for_six_month = filter_end_date.replace(month=filter_start_date_for_six_month_month, day=28)
     else:
       filter_start_date_for_six_month = filter_end_date.replace(month=filter_start_date_for_six_month_month)
   else:
     if filter_end_date.day == 31 and filter_end_date.month >6:
       filter_start_date_for_six_month = filter_end_date.replace(month=filter_start_date_for_six_month_month, day=30)
     elif filter_end_date.day == 31 and filter_end_date.month <=6:
       filter_start_date_for_six_month = filter_end_date.replace(year=filter_end_date.year-1, month=filter_start_date_for_six_month_month, day=30)
     elif filter_end_date.day <31 and filter_end_date.month >6:
       filter_start_date_for_six_month = filter_end_date.replace(month=filter_start_date_for_six_month_month)
     else:
       filter_start_date_for_six_month = filter_end_date.replace(year=filter_end_date.year-1, month=filter_start_date_for_six_month_month)

filter_end_date = filter_end_date + datetime.timedelta(days=1)

self.links = ((
     ('------', {}),
     ('Past week', {
       self.lookup_kwarg_since: str(filter_start_date_for_one_week),
       self.lookup_kwarg_until: str(filter_end_date),
     }),
     ('Past month', {
       self.lookup_kwarg_since: str(filter_start_date_for_one_month),
       self.lookup_kwarg_until: str(filter_end_date),
     }),
     ('Past 6 months', {
       self.lookup_kwarg_since: str(filter_start_date_for_six_month),
       self.lookup_kwarg_until: str(filter_end_date),
     }),
     ('All', {}),
   ))

来源：https://blog.csdn.net/l497626363/article/details/78659921