如何在django视图中限制get_next_by_FOO？包括的代码

Question

我在我的视图中使用了get_next_by_FOO来显示一组记录中下列项目的绝对URL，但是当它到达查询集的末尾时会引发错误。

我该如何阻止我的观点提出这个错误，而只是输出一些HTML让我知道它已经到了集合的末尾？

非常感谢所有帮助。

这是错误消息，我的视图和模板代码。

错误

Exception Type:  DoesNotExist 
    Exception Value: Body matching query does not exist. 

查看

def news_view(request, url): 
news = get_object_or_404(Body, url=url) 
next = news.get_next_by_published() 
pre = news.get_previous_by_published() 
return render_to_response('news/news_view.html', { 
    'news': news, 
    'pre': pre, 
    'next': next 
}, context_instance=RequestContext(request)) 

模板

<a href="{{ next.get_absolute_url }}">Next News</a></p> 
    <a href="{{ pre.get_absolute_url }}">Previous News</a></p> 

Answer 1

蛮力答案是：

def news_view(request, url): 
    news = get_object_or_404(Body, url=url) 
    try: 
     next = news.get_next_by_published() 
    except Body.DoesNotExist: 
     next = None 
    try: 
     pre = news.get_previous_by_published() 
    except Body.DoesNotExist: 
     pre = None 
    return render_to_response('news/news_view.html', { 
     'news': news, 
     'pre': pre, 
     'next': next 
     }, context_instance=RequestContext(request)) 

模板：

{% if next %}<a href="{{ next.get_absolute_url }}">Next News</a></p>{% else %}<span class="disabled">At Last Item</span>{% endif %} 
{% if pre %}<a href="{{ pre.get_absolute_url }}">Previous News</a></p>{% else %}<span class="disabled">At First Item</span>{% endif %} 

Answer 2

我这样做：

def news_view(request, url): 
    news = get_object_or_404(Body, url=url) 
    return direct_to_template(request, 'news/news_view.html', {'news': news,}) 

模板：

{% with news.get_previous_by_pub_date as prev %} 
    {% if prev %} 
     <a class="left btn" href="{{ prev.get_absolute_url }}">Previous News</a> 
    {% endif %} 
{% endwith %} 
{% with news.get_next_by_pub_date as next %} 
    {% if next %} 
     <a class="right btn" href="{{ next.get_absolute_url }}">Next News</a> 
    {% endif %} 
{% endwith %}