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>
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 '''
<!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>
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=8, 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)
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 %}
""" 自定义的分页组件，以后如果想要使用这个分页组件，你需要做如下几件事： 在视图函数中： def pretty_list(request): # 1.根据自己的情况去筛选自己的数据 queryset = models.PrettyNum.objects.all() # 2.实例化分页对象 page_object = Pagination(request, queryset) context = { "queryset": page_object.page_queryset, # 分完页的数据 "page_string": page_object.html() # 生成页码 } return render(request, 'pretty_list.html', context) 在HTML页面中 {% for obj in queryset %} {{obj.xx}} {% endfor %} <ul class="pagination"> {{ page_string }} </ul> """ from django.utils.safestring import mark_safe class Pagination(object): def __init__(self, request, queryset, page_size=10, page_param="page", plus=5): """ :param request: 请求的对象 :param queryset: 符合条件的数据（根据这个数据给他进行分页处理） :param page_size: 每页显示多少条数据 :param page_param: 在URL中传递的获取分页的参数，例如：/etty/list/?page=12 :param plus: 显示当前页的 前或后几页（页码） """ from django.http.request import QueryDict import copy query_dict = copy.deepcopy(request.GET) query_dict._mutable = True self.query_dict = query_dict self.page_param = page_param page = request.GET.get(page_param, "1") if page.isdecimal(): page = int(page) else: page = 1 self.page = page self.page_size = page_size self.start = (page - 1) * page_size self.end = page * page_size self.page_queryset = queryset[self.start:self.end] total_count = queryset.count() total_page_count, div = divmod(total_count, page_size) if div: total_page_count += 1 self.total_page_count = total_page_count self.plus = plus def html(self): # 计算出，显示当前页的前5页、后5页 if self.total_page_count <= 2 * self.plus + 1: # 数据库中的数据比较少，都没有达到11页。 start_page = 1 end_page = self.total_page_count else: # 数据库中的数据比较多 > 11页。 # 当前页<5时（小极值） if self.page <= self.plus: start_page = 1 end_page = 2 * self.plus + 1 else: # 当前页 > 5 # 当前页+5 > 总页面 if (self.page + self.plus) > self.total_page_count: start_page = self.total_page_count - 2 * self.plus end_page = self.total_page_count else: start_page = self.page - self.plus end_page = self.page + self.plus # 页码 page_str_list = [] self.query_dict.setlist(self.page_param, [1]) page_str_list.append('<li><a href="?{}">首页</a></li>'.format(self.query_dict.urlencode())) # 上一页 if self.page > 1: self.query_dict.setlist(self.page_param, [self.page - 1]) prev = '<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode()) else: self.query_dict.setlist(self.page_param, [1]) prev = '<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode()) page_str_list.append(prev) # 页面 for i in range(start_page, end_page + 1): self.query_dict.setlist(self.page_param, [i]) if i == self.page: ele = '<li class="active"><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i) else: ele = '<li><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i) page_str_list.append(ele) # 下一页 if self.page < self.total_page_count: self.query_dict.setlist(self.page_param, [self.page + 1]) prev = '<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode()) else: self.query_dict.setlist(self.page_param, [self.total_page_count]) prev = '<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode()) page_str_list.append(prev) # 尾页 self.query_dict.setlist(self.page_param, [self.total_page_count]) page_str_list.append('<li><a href="?{}">尾页</a></li>'.format(self.query_dict.urlencode())) search_string = """ <li> <form style="float: left;margin-left: -1px" method="get"> <input name="page" style="position: relative;float:left;display: inline-block;width: 80px;border-radius: 0;" type="text" class="form-control" placeholder="页码"> <button style="border-radius: 0" class="btn btn-default" type="submit">跳转</button> </form> </li> """ page_str_list.append(search_string) page_string = mark_safe("".join(page_str_list)) return page_string
从来就没有正确的选择，我们只不过是要努力奋斗，使当初的选择变得正确。
