from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger
def category(request,category_id):
    # raise ValueError
    categories = models.Category.objects.filter(set_as_top_menu=True)

    if category_id == "all":
        articles = models.Article.objects.all().order_by("-id")
    else:
        articles = models.Article.objects.filter(category_id=category_id).order_by("-id")

    paginator = Paginator(articles, 2)  # 每页显示的个数

    page = request.GET.get(‘page‘)#总页数
    try:
        objs = paginator.page(page)
    except PageNotAnInteger:
        # If page is not an integer, deliver first page.
        objs = paginator.page(1)
    except EmptyPage:
        # If page is out of range (e.g. 9999), deliver last page of results.
        objs = paginator.page(paginator.num_pages)

    return render(request,‘index.html‘, {"categories":categories, "articles":objs})

              
　　　　　　　　{% load bbs_tags %}
　　　　　　　　<nav aria-label="...">
                  <ul class="pagination">
                      {% for page in articles.paginator.page_range %}
                         {% if articles.number == page %}
                            <li class="active"><a href="?page={{ page }}">{{ page }} <span class="sr-only">(current)</span></a></li>
                        {% else %}
                             {% render_paginator_btn articles page %}
                        {% endif %}
                      {% endfor %}
                  </ul>
              </nav>

@register.simple_tag
def render_paginator_btn(articles,page):
    current_page = articles.number
    total_page = articles.paginator.num_pages
    display_count = 7#总页数
    if current_page - 0 < 4 and page <= display_count:
        return mark_safe(‘<li><a href="http://www.mamicode.com/?page={page}">{page}</a></li>‘.format(page=page))
    elif total_page - current_page < 3 and page > total_page - display_count:
        return mark_safe(‘<li><a href="http://www.mamicode.com/?page={page}">{page}</a></li>‘.format(page=page))
    elif abs(page - current_page) < 4:
        return mark_safe(‘<li><a href="http://www.mamicode.com/?page={page}">{page}</a></li>‘.format(page=page))
    return ‘‘