day 96 关于分页的使用

分页的学习主要四步骤

from django.db import models

# Create your models here.

class Book(models.Model):
    title = models.CharField(max_length=43)
    price = models.DecimalField(max_digits=9, decimal_places=3)

　　

一 批量创建数据库测试

from django.shortcuts import render,HttpResponse

from .models import *

def add(request):
    book_list = []
    for i in range(1000):
        obj = Book(title="book-%s" % i, price=i*12)
        book_list.append(obj)
    Book.objects.bulk_create(book_list)
    return HttpResponse("添加成功")

　　

二 分页的引用文件

class Pagination(object):

    def __init__(self,current_page,all_count,base_url,params,per_page_num=30,pager_count=11,):
        """
        封装分页相关数据
        :param current_page: 当前页
        :param all_count:    数据库中的数据总条数
        :param per_page_num: 每页显示的数据条数
        :param base_url: 分页中显示的URL前缀
        :param pager_count:  最多显示的页码个数
        """

        try:
            current_page = int(current_page)
        except Exception as e:
            current_page = 1

        if current_page <1:
            current_page = 1

        self.current_page = current_page

        self.all_count = all_count
        self.per_page_num = per_page_num

        self.base_url = base_url

        # 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)

        self.params=params # {"id":1,"title":"python","page":109}--->"id=1&title=python&page=109"

    # 页码的开始 每页显示11条，当前页是2 从11开始（2-1）*11 = 11
    @property
    def start(self):
        return (self.current_page - 1) * self.per_page_num

    # 页码的结束  当前页是2 从 2*11 = 22 根据索引取值到21
    @property
    def end(self):
        return self.current_page * self.per_page_num

# 页码的页面、
    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(11-1)/2个页码
            if self.current_page <= 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 + 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 - self.pager_count_half
                    pager_end = self.current_page + self.pager_count_half + 1

        page_html_list = []

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

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

        page_html_list.append(prev_page)

        for i in range(pager_start, pager_end):
            if i == self.current_page:
                temp = '<li class="active"><a href="%s?page=%s">%s</a></li>' % (self.base_url,i, i,)
            else:
                temp = '<li><a href="%s?page=%s">%s</a></li>' % (self.base_url,i,i,)
            page_html_list.append(temp)

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

        last_page = '<li><a href="%s?page=%s">尾页</a></li>' % (self.base_url,self.all_pager,)
        page_html_list.append(last_page)

        return ''.join(page_html_list)

　　

三 定义页面 引用分页到此

def index(request):
    # 一分页的部分  主要从数据库取出 类里面的变量 的6 个参数 1当前的页码  2 数据总数 3 url
    # 4 get传参数的后缀 5每页显示数据条数 6每页显示多少页码
    # 类的规格形参def __init__(self,current_page,all_count,base_url,params,per_page_num=8,pager_count=11,):
    page_num = request.GET.get("page", 1)  # ? #?????? url的参数 get 传参数 如果url 中是page=22,j
    print("page_num", page_num)  # 点击分页的多少就是多少

    book_list = Book.objects.all()
    total_count = Book.objects.all().count()

    base_url = request.path_info

    params = request.GET   #?????? url的参数 get 传参数 http://127.0.0.1:8000/index/?page=11
    print("params",params)
    # QueryDict: {'page': ['11']} >

    from .utils.page import Pagination
    page = Pagination(page_num, total_count, base_url, params, per_page_num=40, pager_count=11)
    page_html = page.page_html()  # ??????对页面的开始渲染

    # 二数据的部分
    book_list = book_list[page.start:page.end]    #??????

    return render(request, "index.html", locals())

　　

四页面展示

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>
<body>

{% for book in book_list %}
    <li>{{ book.title }}----{{ book.price }}</li>
{% endfor %}

<nav aria-label="Page navigation">
     <ul class="pagination">

         {{ page_html|safe}}
    </ul>

</nav>

</body>
</html>