如何在django模板系统中为主页的每个部分自动选择基本模板中的菜单项?

I have a couple of sections in my project with different page templates, say A.html, B.html, C.html. They all extend base.html. I want to show a navigation menu on the base.html (page header) and show the current page item in a different way, ie. class='selected' appended for the A link on A.html page. I have a couple of sections in my project with