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：

 1 <ul>
 2 {% for contact in contacts %}
 3 <li>{{contact}}<br><br></li>
 4 {% endfor %}
 5 </ul>
 6 
 7 <div>
 8 <center>
 9 {% if contacts.has_previous %}  
10 <a href="?page={{ contacts.previous_page_number }}"> 上一页</a>  
11 {% endif %}  
12 <span>  
13     {% for p in contacts.paginator.page_range %}  
14     {% ifequal p contacts.number %}  
15     <span class="current">{{p}}</span>  
16     {% else %}  
17     <a href="?page={{p}}" title="第{{p}}页"><button>{{p}}</button></a>  
18     {% endifequal %}
19     {% endfor %}  
20 </span>  
21 {% if contacts.has_next %}  
22 <a href="?page={{ contacts.next_page_number }}">下一页 > </a>  
23 {% endif %}  
24 <a>[page:{{ contacts.number }}/{{ contacts.paginator.num_pages }}]</a>
25 </center> 
26 </div> 
27 
28 <br>
29 <form action="/fenye/" method="get">
30     <center>
31     <select name='items'>
32         <option value='10' checked="checked">10 items each page</option>
33         <option value='15'>15  items each page</option>
34         <option value='20'>20  items each page</option>
35     </select>
36     <input type="submit" value="select">
37     </center>     
38 </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：

 1 <ul>
 2 {% for contact in contacts %}
 3 <li>{{contact}}<br><br></li>
 4 {% endfor %}
 5 </ul>
 6 
 7 <div>
 8 <center>
 9 {% if contacts.has_previous %}  
10 <a href="?page={{ contacts.previous_page_number }}"> 上一页</a>  
11 {% endif %}  
12 <span>  
13     {% for p in contacts.paginator.page_range %}  
14     {% ifequal p contacts.number %}  
15     <span class="current">{{p}}</span>  
16     {% else %}  
17     <a href="?page={{p}}" title="第{{p}}页"><button>{{p}}</button></a>  
18     {% endifequal %}
19     {% endfor %}  
20 </span>  
21 {% if contacts.has_next %}  
22 <a href="?page={{ contacts.next_page_number }}">下一页 > </a>  
23 {% endif %}  
24 <a>[page:{{ contacts.number }}/{{ contacts.paginator.num_pages }}]</a>
25 </center> 
26 </div> 
27 <center>
28     <br>
29     <button onclick="window.location.href='http://localhost:8000/page'">Return To Original Page</button>
30 </center>

最后，我们的后端views.py代码如下：

 1 from django.http import HttpResponse
 2 from django.shortcuts import render_to_response
 3 from django.utils.datastructures import MultiValueDictKeyError
 4 from django.core.paginator import Paginator,PageNotAnInteger,EmptyPage
 5 
 6 #show items in default 
 7 def output(request):
 8     # get items show on the page from poems.txt
 9     with open('/home/vagrant/poems.txt', 'r') as f:
10         text = f.readlines()
11         
12     items_each_page = 15  # how many items in each page
13     paginator = Paginator(text, items_each_page)
14     page = request.GET.get('page')  # get 'page'
15     try:
16         contacts = paginator.page(page)
17     except PageNotAnInteger:
18         # If page is not an integer, deliver first page.
19         contacts = paginator.page(1)
20     except EmptyPage:
21         # If page is out of range (e.g. 9999), deliver last page of results.
22         contacts = paginator.page(paginator.num_pages)
23     return render_to_response('page.html',{'contacts': contacts})
24 
25 #show items by your choice
26 def output2(request):
27     with open('/home/vagrant/poems.txt', 'r') as f:
28         text = f.readlines()
29         
30     try:
31         #try to get 'items', if None or failed, do nothing.
32         a = request.GET.get('items')
33         if str(a) != 'None':
34             with open('/home/vagrant/num.txt', 'w') as f:
35                 f.write(a)
36     except:
37         pass
38 
39     with open('/home/vagrant/num.txt','r') as f:
40         items_each_page = int(f.read())
41 
42     paginator = Paginator(text, items_each_page)
43     page = request.GET.get('page')
44     try:
45         contacts = paginator.page(page)
46     except PageNotAnInteger:
47         # If page is not an integer, deliver first page.
48         contacts = paginator.page(1)
49     except EmptyPage:
50         # If page is out of range (e.g. 9999), deliver last page of results.
51         contacts = paginator.page(paginator.num_pages)    
52     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~~