分页
当数据库中数据有很多，我们通常会在前端页面做分页展示。
分页的数据可以在前端页面实现，也可以在后端实现分页。
后端实现分页的原理就是每次只请求一页数据。
准备工作
我们使用脚本批量创建一些测试数据（将下面的代码保存到bulk_create.py文件中放到Django项目的根目录，直接执行即可。）：
import os if __name__ == "__main__": os.environ.setdefault("DJANGO_SETTINGS_MODULE", "about_orm.settings") import django django.setup() from app01 import models bulk_obj = (models.Publisher(name='沙河第{}出版社'.format(i)) for i in range(300)) models.Publisher.objects.bulk_create(bulk_obj)
自定义分页
稳扎稳打版
def publisher_list(request): # 从URL中取当前访问的页码数 try: current_page = int(request.GET.get('page')) except Exception as e: # 取不到或者页码数不是数字都默认展示第1页 current_page = 1 # 总数据量 total_count = models.Publisher.objects.count() # 定义每页显示多少条数据 per_page = 10 # 计算出总页码数 total_page, more = divmod(total_count, per_page) if more: total_page += 1 # 定义页面上最多显示多少页码(为了左右对称，一般设为奇数) max_show = 11 half_show = max_show // 2 # 计算一下页面显示的页码范围 if total_page <= max_show: # 总页码数小于最大显示页码数 page_start = 1 page_end = total_page elif current_page + half_show >= total_page: # 右边越界 page_end = total_page page_start = total_page - max_show elif current_page - half_show <= 1: # 左边越界 page_start = 1 page_end = max_show else: # 正常页码区间 page_start = current_page - half_show page_end = current_page + half_show # 数据索引起始位置 data_start = (current_page-1) * per_page data_end = current_page * per_page publisher_list = models.Publisher.objects.all()[data_start:data_end] # 生成页面上显示的页码 page_html_list = [] page_html_list.append('<nav aria-label="Page navigation"><ul class="pagination">') # 加首页 first_li = '<li><a href="/publisher_list/?page=1">首页</a></li>' page_html_list.append(first_li) # 加上一页 if current_page == 1: prev_li = '<li><a href="#"><span aria-hidden="true">«</span></a></li>' else: prev_li = '<li><a href="/publisher_list/?page={}"><span aria-hidden="true">«</span></a></li>'.format(current_page - 1) page_html_list.append(prev_li) for i in range(page_start, page_end + 1): if i == current_page: li_tag = '<li class="active"><a href="/publisher_list/?page={0}">{0}</a></li>'.format(i) else: li_tag = '<li><a href="/publisher_list/?page={0}">{0}</a></li>'.format(i) page_html_list.append(li_tag) # 加下一页 if current_page == total_page: next_li = '<li><a href="#"><span aria-hidden="true">»</span></a></li>' else: next_li = '<li><a href="/publisher_list/?page={}"><span aria-hidden="true">»</span></a></li>'.format(current_page + 1) page_html_list.append(next_li) # 加尾页 page_end_li = '<li><a href="/publisher_list/?page={}">尾页</a></li>'.format(total_page) page_html_list.append(page_end_li) page_html_list.append('</ul></nav>') page_html = "".join(page_html_list) return render(request, "publisher_list.html", {"publisher_list": publisher_list, "page_html": page_html})
封装保存版
class Pagination(object): """自定义分页（Bootstrap版）""" def __init__(self, current_page, total_count, base_url, per_page=10, max_show=11): """ :param current_page: 当前请求的页码 :param total_count: 总数据量 :param base_url: 请求的URL :param per_page: 每页显示的数据量，默认值为10 :param max_show: 页面上最多显示多少个页码，默认值为11 """ try: self.current_page = int(current_page) except Exception as e: # 取不到或者页码数不是数字都默认展示第1页 self.current_page = 1 # 定义每页显示多少条数据 self.per_page = per_page # 计算出总页码数 total_page, more = divmod(total_count, per_page) if more: total_page += 1 self.total_page = total_page # 定义页面上最多显示多少页码(为了左右对称，一般设为奇数) self.max_show = max_show self.half_show = max_show // 2 self.base_url = base_url @property def start(self): return (self.current_page-1) * self.per_page @property def end(self): return self.current_page * self.per_page def page_html(self): # 计算一下页面显示的页码范围 if self.total_page <= self.max_show: # 总页码数小于最大显示页码数 page_start = 1 page_end = self.total_page elif self.current_page + self.half_show >= self.total_page: # 右边越界 page_end = self.total_page page_start = self.total_page - self.max_show elif self.current_page - self.half_show <= 1: # 左边越界 page_start = 1 page_end = self.max_show else: # 正常页码区间 page_start = self.current_page - self.half_show page_end = self.current_page + self.half_show # 生成页面上显示的页码 page_html_list = [] page_html_list.append('<nav aria-label="Page navigation"><ul class="pagination">') # 加首页 first_li = '<li><a href="{}?page=1">首页</a></li>'.format(self.base_url) page_html_list.append(first_li) # 加上一页 if self.current_page == 1: prev_li = '<li><a href="#"><span aria-hidden="true">«</span></a></li>' else: prev_li = '<li><a href="{}?page={}"><span aria-hidden="true">«</span></a></li>'.format( self.base_url, self.current_page - 1) page_html_list.append(prev_li) for i in range(page_start, page_end + 1): if i == self.current_page: li_tag = '<li class="active"><a href="{0}?page={1}">{1}</a></li>'.format(self.base_url, i) else: li_tag = '<li><a href="{0}?page={1}">{1}</a></li>'.format(self.base_url, i) page_html_list.append(li_tag) # 加下一页 if self.current_page == self.total_page: next_li = '<li><a href="#"><span aria-hidden="true">»</span></a></li>' else: next_li = '<li><a href="{}?page={}"><span aria-hidden="true">»</span></a></li>'.format( self.base_url, self.current_page + 1) page_html_list.append(next_li) # 加尾页 page_end_li = '<li><a href="{}?page={}">尾页</a></li>'.format(self.base_url, self.total_page) page_html_list.append(page_end_li) page_html_list.append('</ul></nav>') return "".join(page_html_list)
封装保存版使用实例
def publisher_list(request): # 从URL中取当前访问的页码数 current_page = int(request.GET.get('page')) # 比len(models.Publisher.objects.all())更高效 total_count = models.Publisher.objects.count() page_obj = Pagination(current_page, total_count, request.path_info) data = models.Publisher.objects.all()[page_obj.start:page_obj.end] page_html = page_obj.page_html() return render(request, "publisher_list.html", {"publisher_list": data, "page_html": page_html})
Django内置分页
内置分页view部分
from django.shortcuts import render from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger L = [] for i in range(999): L.append(i) def index(request): current_page = request.GET.get('p') paginator = Paginator(L, 10) # per_page: 每页显示条目数量 # count: 数据总个数 # num_pages:总页数 # page_range:总页数的索引范围，如: (1,10),(1,200) # page: page对象 try: posts = paginator.page(current_page) # has_next 是否有下一页 # next_page_number 下一页页码 # has_previous 是否有上一页 # previous_page_number 上一页页码 # object_list 分页之后的数据列表 # number 当前页 # paginator paginator对象 except PageNotAnInteger: posts = paginator.page(1) except EmptyPage: posts = paginator.page(paginator.num_pages) return render(request, 'index.html', {'posts': posts})
内置分页HTML代码
<!DOCTYPE html> <html> <head lang="en"> <meta charset="UTF-8"> <title></title> </head> <body> <ul> {% for item in posts %} <li>{{ item }}</li> {% endfor %} </ul> <div class="pagination"> <span class="step-links"> {% if posts.has_previous %} <a href="?p={{ posts.previous_page_number }}">Previous</a> {% endif %} <span class="current"> Page {{ posts.number }} of {{ posts.paginator.num_pages }}. </span> {% if posts.has_next %} <a href="?p={{ posts.next_page_number }}">Next</a> {% endif %} </span> </div> </body> </html>
