10.Django高级之分页器组件
批量插入数据
模板层models.py
from django.db import models
class Books(models.Model):
name = models.CharField(max_length=32)
price = models.DecimalField(max_digits=8,decimal_places=2)
publish = models.CharField(max_length=32)
建表别忘了执行数据库迁移命令哦
python3 manage.py makemigrations python3 manage.py migrate
路由层urls.py
urlpatterns = [
url(r'^books_page/', views.books_page),
]
视图层views.py
# 往Book表里批量插入数据
def books_page(request):
# 第一种方案，每循环一次，操作一下数据库，性能低（相当于进行了1000次的数据库链接）
# for i in range(1000):
# book=models.Books.objects.create(name='图书%s'%i,price=i+10,publish='东京出版社')
#
# 第二种方案，批量插入
book_list=[] # 实例化对象放到列表里
for i in range(1000):
book=models.Books(name='图书%s'%i,price=i+10,publish='东京出版社')
book_list.append(book)
# bulk_create一次性插入，batch_size分批往里面插
models.Books.objects.bulk_create(book_list,batch_size=100)
return HttpResponse('ok')
# 当你想要批量插入数据的时候，使用ORM提供的 bulk_create 能够大大的减少操作时间
Django提供了一个新的类来帮助你管理分页数据，这个模块存放在django.core.paginator.py。 其中有两个核心类，一个是Paginator类，另一个是Page类。
在页面显示分页数据，需要用到Django分页器组件
from django.core.paginator import Paginator
urlpatterns = [ url(r'^books_page/', views.books_page), ]
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.4.1/jquery.min.js"></script> <link href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/3.4.1/css/bootstrap.min.css" rel="stylesheet"> <script src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/3.4.1/js/bootstrap.min.js"></script> </head> <body> <div> <table class="table table-striped"> <thead> <tr> <th>id</th> <th>书名</th> <th>价格</th> <th>出版社</th> </tr> </thead> <tbody> {% for book in book_list %} <tr> <td>{{ book.id }}</td> <td>{{ book.name }}</td> <td>{{ book.price }}</td> <td>{{ book.publish }}</td> </tr> {% endfor %} </tbody> </table> </div> <div> <nav aria-label="Page navigation"> <ul class="pagination"> <li> <a href="#" aria-label="Previous"> <span aria-hidden="true">«</span> </a> </li> <li><a href="#">1</a></li> <li><a href="#">2</a></li> <li><a href="#">3</a></li> <li><a href="#">4</a></li> <li><a href="#">5</a></li> <li> <a href="#" aria-label="Next"> <span aria-hidden="true">»</span> </a> </li> </ul> </nav> </div> </body> </html> 前端book_page.html
视图层views.py及使用方法
from django.shortcuts import render,HttpResponse,redirect
from django.core.paginator import Paginator
def books_page(request):
book_list=models.Books.objects.all() # 拿到所有的书籍
paginator=Paginator(book_list,10) # 实例化得到对象
# Paginator对象的属性
print(paginator.count) # 数据总条数
print(paginator.num_pages) # 总页数
print(paginator.per_page) # 每页显示条数
print(paginator.page_range) # range(1, 101) 页码数可以从1拿到100
print(paginator.page(2)) # page对象，拿出第2页
# Page对象的属性和方法页
page = paginator.page(2) # 当前所在页数
print(page.has_next()) # 是否有下一页
print(page.next_page_number()) # 下一页页码
print(page.has_previous()) # 是否有上一页
print(page.previous_page_number()) # 上一页页码
print(page.object_list) # 分页之后的数据列表
print(page.number) # 当前页
return render(request,'book_page.html',locals())
urlpatterns = [ url(r'^books_page/', views.books_page), ]
# 分页器的终极使用 def books_page(request): # 当前页码，用户访问首页默认是第一页，转成int类型 current_num = int(request.GET.get('page_num', 1)) # 从前端获取page_num book_list = models.Books.objects.all() # 拿到要展示的所有数据 paginator = Paginator(book_list, 20) # 每页显示20条 try: page = paginator.page(current_num) # 取到当前的页码数 except Exception as e: current_num = 1 # 无论选择的大于或者小于强制等于1 page = paginator.page(current_num) # 如果总页码数大于11 if paginator.num_pages > 11: # 当前页码减5小于1，要生成1到12的列表（顾头不顾尾，共11个页码） if current_num - 5 < 1: page_range = range(1, 12) # 当前页码+5大于总页码，生成当前页码减10，到当前页码加1的列表（顾头不顾尾，共11个页码） elif current_num + 5 > paginator.num_pages: page_range = range(paginator.num_pages - 10, paginator.num_pages + 1) else: # 生成当前页码 - 5，到当前页码 + 6的列表 page_range = range(current_num - 5, current_num + 6) # 其它情况，生成的列表就是pageinator的page_range else: page_range = paginator.page_range return render(request, 'book_page.html', locals()) ''' 上一页 1 2 3 4 5 6 7 8 9 10 11 下一页 上一页 21 22 23 24 25 26 27 28 29 30 31 下一页 ''' views.py
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>book_page.html</title> <link rel="stylesheet" href="/static/bootstrap-3.3.7-dist/css/bootstrap.min.css"> <script src="/static/bootstrap-3.3.7-dist/js/bootstrap.min.js"></script> <script src="/static/jquery-3.3.1.js"></script> </head> <body> <div class="container-fluid"> <div class="row"> <div class="col-md-8 col-md-offset-2"> <div class="panel panel-success"> <div class="panel-heading"> <h3 class="panel-title">图书列表展示</h3> </div> <div class="panel-body"> <table class="table table-striped"> <thead> <tr> <th>id</th> <th>书名</th> <th>价格</th> <th>出版社</th> </tr> </thead> <tbody> {% for book in page.object_list %} <tr> <td>{{ book.id }}</td> <td>{{ book.name }}</td> <td>{{ book.price }}</td> <td>{{ book.publish }}</td> </tr> {% endfor %} </tbody> </table> <div class="text-center"> <nav aria-label="Page navigation"> <ul class="pagination"> {% if page.has_previous %} <li> <a href="/books_page/?page_num={{ page.previous_page_number }}" aria-label="Previous"> <span aria-hidden="true">«</span> </a> </li> {% else %} <li class="disabled"> <a href="" aria-label="Previous"> <span aria-hidden="true">«</span> </a> </li> {% endif %} {# 当前循环到的页码数，page_range是一个生成器对象 #} {% for foo in page_range %} {# 如果点中的那个数字等于当前页码数，则渲染成蓝色 #} {% if current_num == foo %} <li class="active"><a href="/books_page/?page_num={{ foo }}">{{ foo }}</a></li> {% else %} {# 不等于就正常渲染 #} <li><a href="/books_page/?page_num={{ foo }}">{{ foo }}</a></li> {% endif %} {% endfor %} {% if page.has_next %} <li> <a href="/books_page/?page_num={{ page.next_page_number }}" aria-label="Next"> <span aria-hidden="true">»</span> </a> </li> {% else %} <li class="disabled"> <a href="" aria-label="Next"> <span aria-hidden="true">»</span> </a> </li> {% endif %} </ul> </nav> </div> </div> </div> </div> </div> </div> <div> </div> </body> </html> books_page.html
当我们需要使用到非django内置的第三方功能或者组件代码的时候，我们一般情况下会创建一个名为utils的文件夹，在该文件夹内对模块进行功能性划分。eg：mypage.py
我们到了后期封装代码的时候，不再局限于函数，而是尽量朝面向对象去封装
将下面封装好的模板拷贝到utils文件夹下的mypage.py（自定义的名字随意取）
class Pagination(object):
def __init__(self, current_page, all_count, per_page_num=2, pager_count=5):
"""
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
"""
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)
后端模板：视图层 views.py
from utils.mypage import Pagination # 导入模板
# 书籍的展示
def books(request):
# 先查询出所有要展示的数据信息，
book_queryset = models.Book.objects.all()
current_page = request.GET.get('page',1)
all_count = book_queryset.count()
# 传值生成对象
page_obj = Pagination(current_page=current_page,all_count=all_count)
# 直接对总数据进行切片操作
page_queryset = book_queryset[page_obj.start:page_obj.end]
# 将page_queryset传递到页面，替换之前的book_queryset
return render(request,'books.html',locals())
前端只需要这一行代码就可以实现分页
<div class="text-center">{{ page_obj.page_html|safe }}</div>
前端示例：book_list.html
{% extends 'home.html' %}
{% block main %}
<script>
$('.index').removeClass('active')
$('.books').addClass('active')
$('.publish').removeClass('active')
$('.author').removeClass('active')
</script>
<div>
<div class="panel panel-primary">
<div class="panel-heading">
<h3 class="panel-title">图书管理</h3>
</div>
<div class="panel-body">
<div>
<a href="/book_add/" class="btn btn-success pull-right">添加书籍</a>
</div>
<br>
<br>
<table class="table table-striped table-hover table-bordered">
<thead>
<tr>
<th>ID</th>
<th>书名</th>
<th>价格</th>
<th>出版日期</th>
<th>出版社</th>
<th>作者</th>
<th>操作</th>
</tr>
</thead>
<tbody>
{% for book in page_queryset %}
<tr>
<td>{{ book.id }}</td>
<td class="warning">{{ book.title }}</td>
<td class="info">{{ book.price }}</td>
<td class="dark">{{ book.publish_date|date:'Y-m-d' }}</td>
<td class="success">{{ book.publish.name }}</td>
<td>
{% for author in book.authors.all %}
{% if forloop.last %}
{{ author.name }}
{% else %}
{{ author.name }}、
{% endif %}
{% endfor %}
</td>
<td>
<a href="{% url 'book_edit' book.pk %}" class="btn btn-primary btn-xs">编辑</a>
<a href="{% url 'book_delete' book.pk %}" class="btn btn-danger btn-xs">删除</a>
<button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal" id="bbb" onclick="AA('{{ html }}')">
Launch
</button>
</td>
</tr>
{% endfor %}
</tbody>
</table>
{# 只需要这一行代码就可以实现分页 #}
<div class="text-center">{{ page_obj.page_html|safe }}</div>
</div>
</div>
</div>
{% endblock %}
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