Django学习（5）优雅地分页展示网页

在我们平时浏览网页时，经常会遇到网页里条目很多的情形，这时就会用到分页展示的功能。那么，在Django中，是如何实现网页分类的功能的呢？答案是Paginator类。

本次分享讲具体展示如何利用Django的Paginator类来实现网页的分页展示功能。

首先我们要展示的内容是159首陶渊明的诗歌，它们储存在'/home/vagrant/poem.txt'文件中。

默认的不分页的网页（page.html）如下：

其模板的代码如下：

 <ul>
 {% for contact in contacts %}
 <li>{{contact}}<br><br></li>
 {% endfor %}
 </ul>

 <div>
 <center>
 {% if contacts.has_previous %}
 <a href="?page={{ contacts.previous_page_number }}"> 上一页</a>
 {% endif %}
 <span>
     {% for p in contacts.paginator.page_range %}
     {% ifequal p contacts.number %}
     <span class="current">{{p}}</span>
     {% else %}
     <a href="?page={{p}}" title="第{{p}}页"><button>{{p}}</button></a>
     {% endifequal %}
     {% endfor %}
 </span>
 {% if contacts.has_next %}
 <a href="?page={{ contacts.next_page_number }}">下一页 > </a>
 {% endif %}
 <a>[page:{{ contacts.number }}/{{ contacts.paginator.num_pages }}]</a>
 </center>
 </div> 

 <br>
 <form action="/fenye/" method="get">
     <center>
     <select name='items'>
         <option value='10' checked="checked">10 items each page</option>
         <option value='15'>15  items each page</option>
         <option value='20'>20  items each page</option>
     </select>
     <input type="submit" value="select">
     </center>
 </form>

该网页中的数字按钮可连接到对应的页码，当然也可以用‘下一页’链接。也可以自由选择每页需要显示的条目数量，如下：

选择好条目数，在点击select按钮，可链接到如下页面：

这个页面（fenye.html）显示每页10条，可以点击按钮‘Return To Original Page’回到刚才的页面（page.html）。该页面（fenye.html）的模板代码如下：

 <ul>
 {% for contact in contacts %}
 <li>{{contact}}<br><br></li>
 {% endfor %}
 </ul>

 <div>
 <center>
 {% if contacts.has_previous %}
 <a href="?page={{ contacts.previous_page_number }}"> 上一页</a>
 {% endif %}
 <span>
     {% for p in contacts.paginator.page_range %}
     {% ifequal p contacts.number %}
     <span class="current">{{p}}</span>
     {% else %}
     <a href="?page={{p}}" title="第{{p}}页"><button>{{p}}</button></a>
     {% endifequal %}
     {% endfor %}
 </span>
 {% if contacts.has_next %}
 <a href="?page={{ contacts.next_page_number }}">下一页 > </a>
 {% endif %}
 <a>[page:{{ contacts.number }}/{{ contacts.paginator.num_pages }}]</a>
 </center>
 </div>
 <center>
     <br>
     <button onclick="window.location.href='http://localhost:8000/page'">Return To Original Page</button>
 </center>

最后，我们的后端views.py代码如下：

 from django.http import HttpResponse
 from django.shortcuts import render_to_response
 from django.utils.datastructures import MultiValueDictKeyError
 from django.core.paginator import Paginator,PageNotAnInteger,EmptyPage

 #show items in default
 def output(request):
     # get items show on the page from poems.txt
     with open('/home/vagrant/poems.txt', 'r') as f:
         text = f.readlines()

     items_each_page = 15  # how many items in each page
     paginator = Paginator(text, items_each_page)
     page = request.GET.get('page')  # get 'page'
     try:
         contacts = paginator.page(page)
     except PageNotAnInteger:
         # If page is not an integer, deliver first page.
         contacts = paginator.page(1)
     except EmptyPage:
         # If page is out of range (e.g. 9999), deliver last page of results.
         contacts = paginator.page(paginator.num_pages)
     return render_to_response('page.html',{'contacts': contacts})

 #show items by your choice
 def output2(request):
     with open('/home/vagrant/poems.txt', 'r') as f:
         text = f.readlines()

     try:
         #try to get 'items', if None or failed, do nothing.
         a = request.GET.get('items')
         if str(a) != 'None':
             with open('/home/vagrant/num.txt', 'w') as f:
                 f.write(a)
     except:
         pass

     with open('/home/vagrant/num.txt','r') as f:
         items_each_page = int(f.read())

     paginator = Paginator(text, items_each_page)
     page = request.GET.get('page')
     try:
         contacts = paginator.page(page)
     except PageNotAnInteger:
         # If page is not an integer, deliver first page.
         contacts = paginator.page(1)
     except EmptyPage:
         # If page is out of range (e.g. 9999), deliver last page of results.
         contacts = paginator.page(paginator.num_pages)
     return render_to_response('fenye.html',{'contacts': contacts})

这样，我们就基本实现了在Django中网页分页展示的功能，而且能够自己选择每一页需要展示的条目的数量，这显然是非常方便使用的。

本次分享到此结束，如有问题，欢迎大家交流与批评~~