面包屑路径导航

import re
from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import HttpResponse,redirect
from app01.models import Permission

class PermissionMiddleWare(MiddlewareMixin):
    def process_request(self,request):
        current_path = request.path
        for reg in ['/login/','/admin/']:
            ret=re.search(reg,current_path)
            if ret:
                return None
        user_id=request.session.get('user_id')
        if not user_id:
            return redirect('/login/')

        permission_list=request.session.get('permission_list')

        request.breadcrumb = []

        for item in permission_list:
            reg='^%s$'%item["url"]
            ret=re.search(reg,current_path)
            if ret:
                show_id=item["pid"] or item["id"]
                request.show_id = show_id
                if item["pid"]:
                    pPermission=Permission.objects.filter(pk=item["pid"]).first()
                    request.breadcrumb.extend(
                        [
                            {
                                'title':pPermission.title,
                                'url':pPermission.url
                            },
                            {
                                'title': item['title'],
                                'url': item['url']
                            }
                        ]
                    )
                else:
                    request.breadcrumb.append(
                        {
                            'title':item['title'],
                            'url':item['url']
                        }
                    )
                return None
        return HttpResponse('无权限访问')

<ol class="breadcrumb">
                {% for foo in request.breadcrumb %}
                    <li><a href="{{ foo.url }}">{{ foo.title }}</a></li>/
                {% endfor %}
</ol>