為什麼要實現分頁？

在大部分網站中分頁的功能都是必要的，尤其是在後臺管理中分頁更是不可或缺

分頁能帶給使用者更好的體驗，也能減輕伺服器的壓力

對於分頁來說，有許多方法都可以實現

例如把資料全部讀取出來在前端用javascript實現，但這樣一次請求全部資料伺服器壓力很大，

還有就是在後端實現，每一次請求部分資料顯示

分頁需求：

1. 每頁顯示的多少條資料
2. 頁面顯示多少個頁碼
3. 上一頁和下一頁
4. 首頁和尾頁

效果演示：

程式碼實現：

分頁類封裝:

在我的app下建立一個page.py檔案，進行封裝，我是先在我的app下建立了一個utils檔案再建立page.py

class Pagination(object):

    def __init__(self, current_page_num, all_count, request, per_page_num=10, pager_count=11):
        """
        封裝分頁相關資料
        :param current_page_num: 當前訪問頁的數字
        :param all_count:    分頁資料中的資料總條數
        :param per_page_num: 每頁顯示的資料條數
        :param pager_count:  最多顯示的頁碼個數
        """
        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

        # 實際總頁碼
        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)  # 5

        # 儲存搜尋條件
        import copy
        self.params = copy.deepcopy(request.GET)  # {"a":"1","b":"2"}

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

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

    # 實現
    def page_html(self):
        # 如果總頁碼 < 11個：
        if self.all_pager <= self.pager_count:
            pager_start = 1
            pager_end = self.all_pager + 1
        # 總頁碼  > 11
        else:
            # 當前頁如果<=頁面上最多顯示11/2個頁碼
            if self.current_page_num <= self.pager_count_half:
                pager_start = 1
                pager_end = self.pager_count + 1
            # 當前頁大於5
            else:
                # 頁碼翻到最後
                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">首頁</a></li>' % (1,)
        page_html_list.append(first_page)

        if self.current_page_num <= 1:
            prev_page = '<li class="disabled"><a href="#">上一頁</a></li>'
        else:
            prev_page = '<li><a href="?page=%s">上一頁</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="#">下一頁</a></li>'
        else:
            next_page = '<li><a href="?page=%s">下一頁</a></li>' % (self.current_page_num + 1,)
        page_html_list.append(next_page)
        last_page = '<li><a href="?page=%s">尾頁</a></li>' % (self.all_pager,)
        page_html_list.append(last_page)

        return ''.join(page_html_list)

在檢視中使用

views.py

# 首先匯入包
from myapp.utils.page import Pagination
from myapp.models import User


def index(request):
    # queryset
    user_list = User.objects.all()
    # 總頁數
    page_count = user_list.count()
    # 當前頁
    current_page_num = request.GET.get("page")
    pagination = Pagination(current_page_num, page_count, request, per_page_num=1)
    # 處理之後的資料
    user_list = user_list[pagination.start:pagination.end]

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

頁面顯示

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/[email protected]/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 樣式  -->
    <div class="dataTables_paginate paging_simple_numbers pull-right">
        <ul class="pagination">
            {{ pagination.page_html|safe }}
        </ul>
    </div>
</div>
</body>
</html>

&n