django filter

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

連鎖查詢  《=》A.objects.filter(a = 'aaa'，c = 'cccccccc')  

當多對多的時候二者會有差別

 

前者的好處是：

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

if XXXXX:

    a.filter(c = 'cccccccc')

 

template filter

{{ aaa|lower }}

lower是函數

filter是函數調用

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()

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