'filter' is not a registered tag library

TemplateSyntaxError at /article-0-1.html

'filter' is not a registered tag library. Must be one of:
admin_list
admin_modify
admin_static
admin_urls
cache
i18n
l10n
log
static
staticfiles
tz

解決：新建的filter.py文件名是filter,封裝這個函數的時候也是這個文件名。

from django import template


register = template.Library()
@register.simple_tag
def select_all(arg_dict):

因此：在HTML文件里{%load filter%},而不是def ***:這個函數名***