Django自带的分页插件
现象这样的一个问题 ，分页是不是有规律的，是个什么样的规律？，
假如我们对每页的数据固定显示20条 是什么样的呢？
pageSize=20 每页多少条
page=7 页码
| 每页条数（pageSize） |
页码 |
每页数据 |
| 10 |
1 |
0-10 |
| 10 |
2 |
10-20 |
| 10 |
7 |
60-70 |
| 10 |
n |
(N-1)*pageSize-n*pageSize |
是不是这样？这就是最基本的分页方式
最基本的分页思路
def list_students(request):
if request.method == "GET":
page = request.GET.get("page") #获取页码
page_size = request.GET.get("page_size") #获取每页条数
if not page: #设置默认页码为1
page = 1
if not page_size: #设置默认每页5
page_size = 5
page = int(page) #防止url直接传过来字符串的页码
page_size = int(page_size) #防止url直接传过来字符串的页码
start = (page-1)*page_size #页码数据开头的索引
end = page*page_size #页码数据结尾的索引
students = Student.objects.order_by("id") #排序查询
lenth = len(students) #获取长度
page_num = lenth/page_size #计算页码范围
if page_num != int(page_num): #判断页码是否为整数
page_num += 1
page_num = int(page_num)
page_range = range(1,page_num+1) #页码范围
data = students[start:end] #截取数据
return render(request,"stu_list.html",{“data”:data,”page_range”:page_range})使用django的分页插件进行分页
1、查询所有的数据
2、将数据传入分页的函数
3、调用具体页的数据
from django.core.paginator import Paginator
def list_students(request):
if request.method == "GET":
page = request.GET.get("page")
page_size = request.GET.get("page_size")
if not page:
page = 1
if not page_size:
page_size = 5
page = int(page)
all_data = Student.objects.all() #查询所有的数据 --->1<---
all_page = Paginator(all_data,int(page_size)) #将数据和单页条数放到Paginator里面 all_data = Student.objects.all() #查询所有的数据 --->2<---
data = all_page.page(page) #获取具体页的数据 --->3<---
return render(request,"stu_list.html",locals())
#基于分页实例
<P>
<p>
+++++++++++++++++++++总条数数+++++++++++++++++++++++++++
<br>{{ all_page.count }}
</p>
<p>
+++++++++++++++++++++总页数+++++++++++++++++++++++++++
<br>{{ all_page.num_pages }}
</p>
<p>
+++++++++++++++++++++页码范围+++++++++++++++++++++++++++
<br>{{ all_page.page_range }}
</p>
</P>
#基于当前分页
<p>
<p>
+++++++++++++++++++++当前页具体数据+++++++++++++++++++++++++++
<br>{{ data.object_list }}
</p>
<p>
+++++++++++++++++++++当前页码+++++++++++++++++++++++++++
<br>{{ data.number }}
</p>
<p>
+++++++++++++++++++++当前是否有上一页+++++++++++++++++++++++++++
<br>{{ data.has_previous }}<br>
+++++++++++++++++++++当前是否有下一页+++++++++++++++++++++++++++
<br>{{ data.has_other_pages }}
</p>
<p>
+++++++++++++++++++++开始索引+++++++++++++++++++++++++++
<br>{{ data.start_index }}<br>
+++++++++++++++++++++结束索引+++++++++++++++++++++++++++
<br>{{ data.end_index }}
</p>
</p>高级分页思路
Django查询本身是有惰性的，all并不是将所有的数据查询出来，只有在排序或者截取的时候，才会 具体查询。
查询 第1页到第5页，数据库只查询前50条数据，
查询 第6页的时候，会查询50-100。
首先编写实例代码
"""
page_size = 10
当我们查询第1-5页的时候，不对所有数据进行查询，只查询前50条,也就是5页
#page 1 select_range 0-50 return_range 1-10 r_n = 1 s_n = 1
#page 2 select_range 0-50 return_range 10-20 r_n = 2 s_n = 1
#page 3 select_range 0-50 return_range 20-30 r_n = 3 s_n = 1
#page 4 select_range 0-50 return_range 30-40 r_n = 4 s_n = 1
#page 5 select_range 0-50 return_range 40-50 r_n = 5 s_n = 1
#page 6 select_range 50-100 return_range 0-10 r_n = 1 s_n = 2
#page 7 select_range 50-100 return_range 10-20 r_n = 2 s_n = 2
#page 8 select_range 50-100 return_range 20-30 r_n = 3 s_n = 2
#page 9 select_range 50-100 return_range 30-40 r_n = 4 s_n = 2
#page n (s_n-1)*50-s_n*50
"""
total = list(range(103))
while True:
page = int(input(">>>"))
if page%5 == 0:
s_n = int(page/5)
r_n = 5
else:
s_n = int(page / 5)+1
r_n = page%5
select_start = (s_n-1)*50
select_end = s_n*50
select_range = total[select_start:select_end]
return_start = (r_n-1)*10
return_end = r_n*10
return_range = select_range[return_start:return_end]
page_range = [3,4,5,6,7]
if page <= 3:
page_range = range(1,6)
else:
page_range = range(page-2,page+3)
print("+++++++++++++++++++++++++++++++++++++++++++++++++++")
print("当前的页码是:%s" % page)
print("当前的大页码(s_n)是:%s" % s_n)
print("当前的小页码是(r_n):%s" % r_n)
print("查询的大范围（50条范围是）:%s" % str(select_range))
print("查询的小范围（10条范围是）:%s" % str(return_range))
print("反馈的页码是 :%s" % str(list(page_range)))
print("+++++++++++++++++++++++++++++++++++++++++++++++++++")然后将代码嵌入到我们的查询试图当中
def list_students(request):
if request.method == "GET":
page = request.GET.get("page")
page_size = request.GET.get("page_size")
onece_page = 5
if not page:
page = 1
if not page_size:
page_size = 5
page = int(page)
page_size =int(page_size)
if page % onece_page == 0:
s_n = int(page / onece_page)
r_n = onece_page
else:
s_n = int(page / onece_page) + 1
r_n = page % onece_page
total = Student.objects.all() # 查询所有的数据
select_start = (s_n - 1) * onece_page*page_size
select_end = s_n * onece_page*page_size
select_range = total[select_start:select_end]
return_start = (r_n - 1) * page_size
return_end = r_n * page_size
return_range = select_range[return_start:return_end]
if page <= 3:
page_range = range(1, 6)
else:
page_range = range(page - 2, page + 3)
return render(request,"stu_list.html",{"data":return_range,"page_range":page_range})