Django 自定义分页器

为什么要实现分页？

在大部分网站中分页的功能都是必要的，尤其是在后台管理中分页更是不可或缺

分页能带给用户更好的体验，也能减轻服务器的压力

对于分页来说，有许多方法都可以实现

例如把数据全部读取出来在前端用javascript实现，但这样一次请求全部数据服务器压力很大，

还有就是在后端实现，每一次请求部分数据显示

分页需求：

1. 每页显示的多少条数据
2. 页面显示多少个页码
3. 上一页和下一页
4. 首页和尾页

效果演示：

代码实现：

分页类封装:

在我的app下创建一个page.py文件，进行封装，我是先在我的app下创建了一个utils文件再创建page.py

class Pagination(object):

    def __init__(self, current_page_num, all_count, request, per_page_num=10, pager_count=11):
        """
        封装分页相关数据
        :param current_page_num: 当前访问页的数字
        :param all_count:    分页数据中的数据总条数
        :param per_page_num: 每页显示的数据条数
        :param pager_count:  最多显示的页码个数
        """
        try:
            current_page_num = int(current_page_num)
        except Exception as e:
            current_page_num = 1

        if current_page_num < 1:
            current_page_num = 1

        self.current_page_num = current_page_num

        self.all_count = all_count
        self.per_page_num = per_page_num

        # 实际总页码
        all_pager, tmp = divmod(all_count, per_page_num)
        if tmp:
            all_pager += 1
        self.all_pager = all_pager

        self.pager_count = pager_count
        self.pager_count_half = int((pager_count - 1) / 2)  #

        # 保存搜索条件
        import copy
        self.params = copy.deepcopy(request.GET)  # {"a":"1","b":"2"}

    # 开始
    @property
    def start(self):
        return (self.current_page_num - 1) * self.per_page_num

    # 结束
    @property
    def end(self):
        return self.current_page_num * self.per_page_num

    # 实现
    def page_html(self):
        # 如果总页码 < 11个：
        if self.all_pager <= self.pager_count:
            pager_start = 1
            pager_end = self.all_pager + 1
        # 总页码  > 11
        else:
            # 当前页如果<=页面上最多显示11/2个页码
            if self.current_page_num <= self.pager_count_half:
                pager_start = 1
                pager_end = self.pager_count + 1
            # 当前页大于5
            else:
                # 页码翻到最后
                if (self.current_page_num + self.pager_count_half) > self.all_pager:

                    pager_start = self.all_pager - self.pager_count + 1
                    pager_end = self.all_pager + 1

                else:
                    pager_start = self.current_page_num - self.pager_count_half
                    pager_end = self.current_page_num + self.pager_count_half + 1

        page_html_list = []

        first_page = '<li><a href="?page=%s">首页</a></li>' % (1,)
        page_html_list.append(first_page)

        if self.current_page_num <= 1:
            prev_page = '<li class="disabled"><a href="#">上一页</a></li>'
        else:
            prev_page = '<li><a href="?page=%s">上一页</a></li>' % (self.current_page_num - 1,)

        page_html_list.append(prev_page)

        # self.params=copy.deepcopy(request.GET) # {"a":"1","b":"2"}

        for i in range(pager_start, pager_end):

            self.params["page"] = i

            if i == self.current_page_num:
                temp = '<li class="active"><a href="?%s">%s</a></li>' % (self.params.urlencode(), i)
            else:
                temp = '<li><a href="?%s">%s</a></li>' % (self.params.urlencode(), i,)
            page_html_list.append(temp)

        if self.current_page_num >= self.all_pager:
            next_page = '<li class="disabled"><a href="#">下一页</a></li>'
        else:
            next_page = '<li><a href="?page=%s">下一页</a></li>' % (self.current_page_num + 1,)
        page_html_list.append(next_page)
        last_page = '<li><a href="?page=%s">尾页</a></li>' % (self.all_pager,)
        page_html_list.append(last_page)

        return ''.join(page_html_list)

在视图中使用

views.py

# 首先导入包
from myapp.utils.page import Pagination
from myapp.models import User

def index(request):
    # queryset
    user_list = User.objects.all()
    # 总页数
    page_count = user_list.count()
    # 当前页
    current_page_num = request.GET.get("page")
    pagination = Pagination(current_page_num, page_count, request, per_page_num=1)
    # 处理之后的数据
    user_list = user_list[pagination.start:pagination.end]

    content = {
        "user_list": user_list,
        "pagination": pagination,
    }
    return render(request, "user_list.html", content)

页面显示

user_list.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>index</title>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css">
</head>
<body>
<div class="container">
    <table class="table table-striped">
        <thead>
        <tr>
            <th>name</th>
        </tr>
        </thead>
        <tbody>
        {% for user in user_list %}
            <tr>
                <td>{{ user.name }}</td>
            </tr>
        {% endfor %}
        </tbody>
    </table>
    <!-- bootstrap 样式  -->
    <div class="dataTables_paginate paging_simple_numbers pull-right">
        <ul class="pagination">
            {{ pagination.page_html|safe }}
        </ul>
    </div>
</div>
</body>
</html>