标签：field start rom 总数 令行 rop 解决 并且 页码
我们要写一个批量插入数据库并且展示到页面上的代码
#models.py
from django.db import models
# Create your models here.
class Book(models.Model):
title = models.CharField(max_length=32)#老规矩 执行命令行 完成数据的迁移
mikemigrations
migrate#views.py
def index(request):
# 1.往书籍表中插入数据 1000
for i in range(1000): # 这种插入方式 效率极低
models.Book.objects.create(title='第%s本书'%i)
book_queryset=models.Book.objects.all()
return render(request,'index.html',locals())#index.html
<body>
{% for book_obj in book_queryset %}
<p>{{ book_obj.title }}</p>
{% endfor %}
</body>运行该项目，发现由于插入数据的时间太久而导致的网页上数据展示等待的时间太久，这种原始插入方式效率贼低
为了解决这个问题
#仅在views.py修改一下index函数
book_list = []
for i in range(100000):
book_list.append(models.Book(title='第%s本书'%i))
models.Book.objects.bulk_create(book_list) # 批量插入数据
return render(request,'index.html',locals())不一会网页很快地显示出来了
完成数据的迅速展示的效果后 还得对网页上大量的数据进行分页一下
#views.py
def index(request):
# 1.获取用户想要访问的页码数
current_page = request.GET.get('page',1) # 如果没有page参数 默认就展示第一页
# 转成整型
current_page = int(current_page)
# 2.每页展示10条数据
per_page_num = 10
# 3.定义起始位置和终止位置
start_page = (current_page - 1) * per_page_num
end_page = current_page * per_page_num
# 4.统计数据的总条数
book_queryset = models.Book.objects.all()
all_count = book_queryset.count()
# 5.求数据到底需要多少页才能展示完
page_num, more = divmod(all_count,per_page_num) # divmod(100,10)
if more:
page_num += 1
# page_num就觉得了 需要多少个页码
page_html = ''
xxx = current_page # xxx就是用户点击的数字
if current_page < 6:
current_page = 6
for i in range(current_page-5,current_page+6):
if xxx == i:
page_html += '<li class="active"><a href="?page=%s">%s</a></li>'%(i,i)
else:
page_html += '<li><a href="?page=%s">%s</a></li>' % (i, i)
book_queryset = book_queryset[start_page:end_page]
return render(request,'index.html',locals()) #index.html部分核心代码
{% for book_obj in book_queryset %}
<p>{{ book_obj.title }}</p>
{% endfor %}
<nav aria-label="Page navigation">
<ul class="pagination">
<li>
<a href="#" aria-label="Previous">
<span aria-hidden="true">«</span>
</a>
</li>
{{ page_html|safe }}
<li>
<a href="#" aria-label="Next">
<span aria-hidden="true">»</span>
</a>
</li>
</ul>
</nav>通过纯手撸分页器 大概了解分页器原理，上面的代码只需要掌握思路就行 不是以后真的要纯手撸哈哈哈，那怎么用别人封装好的分页器呢？
在app01中创建一个utils文件夹 创建一个名为mypage.py，将以下代码直接拷贝过去
class Pagination(object):
def __init__(self,current_page,all_count,per_page_num=2,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 pager_count: 最多显示的页码个数
用法:
queryset = model.objects.all()
page_obj = Pagination(current_page,all_count)
page_data = queryset[page_obj.start:page_obj.end]
获取数据用page_data而不再使用原始的queryset
获取前端分页样式用page_obj.page_html
"""
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
# 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)
@property
def start(self):
return (self.current_page - 1) * self.per_page_num
@property
def end(self):
return self.current_page * self.per_page_num
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 <= 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_end = self.all_pager + 1
pager_start = self.all_pager - self.pager_count + 1
else:
pager_start = self.current_page - self.pager_count_half
pager_end = self.current_page + self.pager_count_half + 1
page_html_list = []
# 添加前面的nav和ul标签
page_html_list.append('''
<nav aria-label='Page navigation>'
<ul class='pagination'>
''')
first_page = '<li><a href="?page=%s">首页</a></li>' % (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="?page=%s">上一页</a></li>' % (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="?page=%s">%s</a></li>' % (i, i,)
else:
temp = '<li><a href="?page=%s">%s</a></li>' % (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="?page=%s">下一页</a></li>' % (self.current_page + 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)
# 尾部添加标签
page_html_list.append('''
</nav>
</ul>
''')
return ''.join(page_html_list)#后端views.py
from app01.utils.mypage import Pagination
# 使用封装好的分页器代码
def login(request):
book_queryset = models.Book.objects.all()
#获取当前用户点击的页码
current_page = request.GET.get('page',1)
#获取数据的总数量
all_count = book_queryset.count()
# 1.实例化产生对象
page_obj = Pagination(current_page=current_page,all_count=all_count)
# 2.对真实数据进行切片操作
page_queryset = book_queryset[page_obj.start:page_obj.end]
return render(request,'login.html',locals())别忘了前端
#index.html
{% for book_obj in page_queryset %}
<p>{{ book_obj.title }}</p>
{% endfor %}
{{ page_obj.page_html|safe }}好了 ，白嫖的代码到手
标签：field start rom 总数 令行 rop 解决 并且 页码
原文地址：https://www.cnblogs.com/demiao/p/11760782.html
