# 分页功能的实现

## 直接上代码吧:

import math

class Page:

def __init__(self, total_num, page_num, every_page_num=10, show_page_num=9):
"""
:param total_num: 数据库获取到的数据的总数
:param page_num: 前端获取的页数
:param every_page_num: 自定义每页显示条数
:param show_page_num: 显示分页数目
"""
self.total_num = total_num
self.page_num = page_num
self.every_page_num = every_page_num
self.show_page_num = show_page_num
self.page_tags_html = ''
self.page_start_num = 0
self.page_end_num = 0
self.start_page_num = 1
self.end_page_num = 1
try:
self.page_num = int(self.page_num)
except:
self.page_num = 1
# 通过向上取整计算出数据的总页数
self.total_page_num = math.ceil(self.total_num / self.every_page_num)
if self.total_page_num:
# 判断从前端得到的页码数是否小于1，小于1就重置为1
if self.page_num < 1:
self.page_num = 1
# 判断从前端得到的页码数是否大于总页码数，大于就重置为最大页码数
elif self.page_num > self.total_page_num:
self.page_num = self.total_page_num
# 当前页的开始数据
self.page_start_num = (self.page_num - 1) * self.every_page_num
# 当前页的结束数据
self.page_end_num = (self.page_num) * self.every_page_num
# 判断总页码数和要展示的页数，如果总页码数大于要展示的页码数就展示对应的页数否则有多少页就展示多少页
if self.total_page_num > self.show_page_num:
self.start_page_num = self.page_num - (self.show_page_num // 2)
self.end_page_num = self.page_num + (self.show_page_num // 2)
if self.start_page_num < 1:
self.start_page_num = 1
self.end_page_num = self.show_page_num
if self.end_page_num > self.total_page_num:
self.end_page_num = self.total_page_num
self.start_page_num = (self.total_page_num - self.show_page_num)
else:
self.start_page_num = 1
self.end_page_num = self.total_page_num

@property
def start(self):
return self.page_start_num

@property
def end(self):
return self.page_end_num

@property
def html(self):
pre_page_num = self.page_num - 1 if self.page_num > 1 else self.page_num
next_page_num = self.page_num + 1 if self.page_num < self.total_page_num else self.total_page_num
The_first_page = '<li><a href="?page=1">首页</a>' \
f'</li><li><a href="?page={pre_page_num}">&laquo;</a></li>'
The_last_page = f'<li><a href="?page={next_page_num}">&raquo;</a></li>' \
f'<li><a href="?page={self.total_page_num}">尾页</a></li></ul></nav>'

self.page_tags_html = f'<nav aria-label="Page navigation"> <ul class="pagination">{The_first_page}'
for i in range(self.start_page_num, self.end_page_num + 1):
if i == self.page_num:
self.page_tags_html += f'<li class="active"><a href="?page={i}">{i}</a></li>'
else:
self.page_tags_html += f'<li><a href="?page={i}">{i}</a></li>'
self.page_tags_html += The_last_page
return self.page_tags_html



import math
import copy

class Page:
def __init__(self, total_num, page_num, request, every_page_num=10, show_page_num=9):
"""
:param total_num: 数据库获取到的数据的总数
:param request: 当前url请求数据，用于获取url参数
:param page_num: 前端获取的页数
:param every_page_num: 自定义每页显示条数
:param show_page_num: 显示分页数目
"""
self.total_num = total_num
self.page_num = page_num
self.every_page_num = every_page_num
self.show_page_num = show_page_num
self.page_tags_html = ''
self.page_start_num = 0
self.page_end_num = 0
self.start_page_num = 1
self.end_page_num = 1

try:
self.page_num = int(self.page_num)
except:
self.page_num = 1

# 获取当前url请求中的参数
params = copy.deepcopy(request.GET)
self.params = params
# 通过向上取整计算出数据的总页数
self.total_page_num = math.ceil(self.total_num / self.every_page_num)
if self.total_page_num:
# 判断从前端得到的页码数是否小于1，小于1就重置为1
if self.page_num < 1:
self.page_num = 1
# 判断从前端得到的页码数是否大于总页码数，大于就重置为最大页码数
elif self.page_num > self.total_page_num:
self.page_num = self.total_page_num
# 当前页的开始数据
self.page_start_num = (self.page_num - 1) * self.every_page_num
# 当前页的结束数据
self.page_end_num = (self.page_num) * self.every_page_num
# 判断总页码数和要展示的页数，如果总页码数大于要展示的页码数就展示对应的页数否则有多少页就展示多少页
if self.total_page_num > self.show_page_num:
self.start_page_num = self.page_num - (self.show_page_num // 2)
self.end_page_num = self.page_num + (self.show_page_num // 2)
if self.start_page_num < 1:
self.start_page_num = 1
self.end_page_num = self.show_page_num
if self.end_page_num > self.total_page_num:
self.end_page_num = self.total_page_num
self.start_page_num = (self.total_page_num - self.show_page_num)
else:
self.start_page_num = 1
self.end_page_num = self.total_page_num

@property
def start(self):
return self.page_start_num

@property
def end(self):
return self.page_end_num

@property
def html(self):

pre_page_num = self.page_num - 1 if self.page_num > 1 else self.page_num
next_page_num = self.page_num + 1 if self.page_num < self.total_page_num else self.total_page_num
self.params["page"] = 1
The_home_page_html = f'<li><a href="?{self.params.urlencode()}">首页</a></li>'
self.params["page"] = pre_page_num
pre_page_num_html = f'<li><a href="?{self.params.urlencode()}">&laquo;</a></li>'
The_first_page_html = The_home_page_html + pre_page_num_html
self.params["page"] = next_page_num
next_page_num_html = f'<li><a href="?{self.params.urlencode()}">&raquo;</a></li>'
self.params["page"] = self.total_page_num
The_end_page_html = f'<li><a href="?{self.params.urlencode()}">尾页</a></li></ul></nav>'
The_last_page_html = next_page_num_html + The_end_page_html
self.page_tags_html = f'<nav aria-label="Page navigation"> <ul class="pagination">{The_first_page_html}'
for i in range(self.start_page_num, self.end_page_num + 1):
self.params["page"] = i
if i == self.page_num:
self.page_tags_html += f'<li class="active"><a href="?{self.params.urlencode()}">{i}</a></li>'
else:
self.page_tags_html += f'<li><a href="?{self.params.urlencode()}">{i}</a></li>'
self.page_tags_html += The_last_page_html

return self.page_tags_html


### 分页的使用：

class Home(views.View):
def get(self, request):
article_list = models.Article.objects.all()
totol_num = article_list.count()
page_num = request.GET.get("page", 1)
# 分页实例化传参
page_obj = Page(total_num=totol_num, page_num=page_num, every_page_num=9)
# 根据分页拿到的start和end切片得到所要的数据
data = article_list[page_obj.start:page_obj.end]
# 调用html方法得到分页的html代码片段
page_html = page_obj.html
return render(request, 'home.html', {'article_list': data, 'page_html': page_html})


# ps:在python脚本中调用django环境实现数据库批量添加数据操作

import os
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "fenye.settings")

if __name__ == "__main__":
import django
django.setup()
from app01 import models

def create():
obj_list = [models.Book(name = f"pyhton{i}") for i in range(160)]
models.Book.objects.bulk_create(obj_list)

create()
#
# def delete():
#     models.Book.objects.all().delete()

# delete()


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