django 分页和cookie

分页功能实现

首先在models.py文件中创建一个Host表，在里面添加数据。

from django.db import models

class Host(models.Model):
        HostName = models.CharField(max_length=256)
        IP = models.GenericIPAddressField()

在views.py中主要是使用mark_safe这个函数渲染字符串

def index(request,page):
    try:
        page = int(page)
    except:
        page = 1
    counts = models.Host.objects.all().count()
    #确定分页数量
    per_item = 10
    start = (page-1)*per_item
    end = page*per_item
    temp = divmod(counts,per_item)
    if temp[1] == 0:
        all_page_count = temp[0]
    else:
        all_page_count = temp[0] + 1
    result = models.Host.objects.all()[start:end]
    #渲染分页
    page_html = []
    first_html = "<a href='/app06/index/%d'>首页</a>" % (1)
    page_html.append(first_html)
    if page <= 1:
        prev_html = "<a href='#nowhere'>上一页</a>"
    else:
        prev_html = "<a href='/app06/index/%d'>上一页</a>" % (page-1)
    page_html.append(prev_html)
    for i range(all_page_count):
        if page == i+1:
            a_html = "<a class='selected 'href='/app06/index/%d'>%d</a>" % (i+1,i+1)
        else:
            a_html = "<a 'href='/app06/index/%d'>%d</a>" % (i+1,i+1)
    next_html = "<a href='/app06/index/%d'>下一页</a>" % (page+1)
    page_html.append(next_html)
    end_html = "<a href='/app06/index/%d'>尾页</a>" % (all_page_count)
    page_html.append(end_html)
    page_string = mark_safe(''.join(page_html))
    ret = {'data':result,'count':counts,'page':page_string}
    return render_to_response('fenye.html',ret)

首先根据总条目和每页的条目计算出分页的数量；获取到所有的主机条目；然后分页，首页，上一页，下一页，尾页，在for循环中遍历所有页的数量，当遍历的条目i+1（从0开始）

与page相等时，就是当前页，否则是其他页。

在fenye.html中

<table border="1px solid #c40000">
{% for item in data %}
       <tr>
            <td>{{ item.HostName }}</td>
            <td>{{ item.IP }}</td>
       </tr>
{% endfor %}
</table>
<div>总条数：{{ count }}</div>
<div id='Pageing'>{{ page }}</div>

对代码进行改进

使用面向对象的思想将分页部分封装，与渲染部分放在一个新的html_helper.py文件中：

class PageInfo(object):
    def __init__(self,current_page,all_count,per_item=5):
        self.CurrentPage = current_page
        self.AllCount = all_count
        self.PerItem = per_item
    @property                     #通过装饰器@property可以将类的方法以属性的方式调用
    def start(self):
        return (self.CurrentPage-1)*self.PerItem
    @property
    def end(self):
        return self.CurrentPage*self.PerItem
    @property
    def All_page_count(self):
        temp = divmod(self.AllCount,self.PerItem)
        if temp[1] == 0:
            all_page_count = temp[0]
        else:
            all_page_count = temp[0]+1
        return all_page_count
        
def Pager(page,all_page_count):
    page_html = []
    first_html = "<a href='/app06/index/%d/'>首页</a>" % (1)
    page_html.append(first_html)
    if page <= 1:
        prev_html = "<a href='#nowhere'>上一页</a>"
    else:
        prev_html = "<a href='/app06/index/%d'>上一页</a>" % (page-1)
    page_html.append(prev_html)
    #让当前页在中间显示
    begin = page - 6
    end = page + 5
    if all_page_count < 11:
        begin = 0
        end = all_page_count
    else:
        if page < 6:
            begin = 0
            end = 11
        else:
            if page + 6 > all_page_count:
                begin = page - 5
                end = all_page_count
            else:
                begin = page - 6
                end = page + 5
    
    for i in range(begin,end):
        if page == i+1:
            a_html = "<a href='/app06/index/%d/' class='selected'>%d</a>" % (i+1,i+1)
        else:
            a_html = "<a href='/app06/index/%d/'>%d</a>" (i+1,i+1)
        page_html.append(a_html)
    
    next_html = "<a href='/app06/index/%d'>下一页</a>" % (page+1)
    page_html.append(next_html)
    end_html = "<a href='/app06/index/%d/'>尾页</a>" % (all_page_count)
    page_html.append(end_html)
    page_string = mark_safe(''.join(page_html))
    return page_string

这样在views.py中就可以修改为：

def index(request,page):
    try:
        page = int(page)
    except Exception as e:
        page = 1
    counts = models.Host.objects.all().count()
    print(page)
    pageObj = html_helper.PageInfo(page,counts,per_item)
    result = models.Host.objects.all()[pageObj.start:pageObj.end]
    page_string = html_helper.Pager(page,pageObj.All_page_count)
    ret = {'data':result,'count':counts,'page':page_string}
    return render_to_response('fenye.html',ret)

实现效果：

可以通过设置cookie的方式改变每页的显示条目，在fenye.html中

<table border="1px solid #c40000">
{% for item in data %}
    <tr>
        <td>{{ item.HostName }}</td>
        <td>{{ item.IP }}</td>
    </tr>
{% endfor %}
</table>
<div>总条数：{{ count }}</div>
<div id='Pageing'>{{ page }}</div>
<div>
    <select id='s1' onchange="ChangePageItem(this);">
    <option value='10'>10</option>
    <option value='30'>30</option>
    <option value='50'>50</option>
    <option value='100'>100</option>
    <option value='500'>500</option>
    </select>
</div>
<script type='text/javascript'>
//当页面加载完成时执行，获取初始cookie的值
$(function(){
    var per_item = $.cookie('pager_num');
    if(per_item){
        $('#s1').val(per_item); 
    }
    else{
        $.cookie('pager_num',10,{path:'/'});
    }
})
function ChangePageItem(arg){
    //创建或修改cookie的值，当发生改变时
    var value = $(arg).val();
    $.cookie('pager_num',value,{path:'/'});
}
</script>

在views.py中修改为，其他文件保持不变

def index(request,page):
    try:
        per_item = int(request.COOKIES.get('pager_num',10))
    except Exception as e:
        per_item = 10
    print(request.COOKIES)
    try:
        page = int(page)
    except Exception as e:
        page = 1
    counts = models.Host.objects.all().count()
    print(page)
    pageObj = html_helper.PageInfo(page,counts,per_item)
    result = models.Host.objects.all()[pageObj.start:pageObj.end]
    page_string = html_helper.Pager(page,pageObj.All_page_count)
    ret = {'data':result,'count':counts,'page':page_string}
    return render_to_response('fenye.html',ret)

实现效果：

当改变显示数量时