django filter

A.objects.filter(a = 'aaa').filter(c = 'cccccccc')

连锁查询  《=》A.objects.filter(a = 'aaa'，c = 'cccccccc')  

当多对多的时候二者会有差别

 

前者的好处是：

a = A.objects.filter(a = 'aaa')

if XXXXX:

    a.filter(c = 'cccccccc')

 

template filter

{{ aaa|lower }}

lower是函数

filter是函数调用

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

 {% load poll_extras %}

from django import template 
register = template.Library()
@register.filter

def lower(value): # Only one argument.
    return value.lower()

 
本身写tags
https://docs.djangoproject.com/en/1.4/howto/custom-template-tags/