try:
book = Book.objects.get(id=book_id)
except Book.DoesNotExist:
raise Http404("书籍不存在")
{% url 'some-url-name' v1 v2 %}
{# 截取前140个字 #}
{{ book.summary|truncatechars:140 }}
{% for tag in booklist.tags.all|slice:":5" %}
<a href="{% url 'tag' tag.id %}" class="booklist-tag">#{{ tag.name }}</a>
{% endfor %}
{{ wpis.entry.lastChangeDate|date:'Y-m-d H:i' }}