templatetags/
    __init__.py
    mytags.py

from django import template

register = template.Library()

@register.filter
def startswith(value, start):
    """
    实现python中的 startswith py2中多一个unicode
    """
    if isinstance(value, (str, unicode)):
        return value.startswith(start)
    else:
        return False

'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],

            # 以下是新加的内容
            'libraries': {
                "mytags": "chart.templatetags.mytags",
            },
        },

{% load mytags %}

{% if field|startswith:"http" %}
     <td><a href="{{ field }}">{{ field }}</a></td>
 {% else %}
     <td>{{ field }}</td>
 {% endif %}