分页器
<!--前端-->
{% for book in page_queryset %}
<p>{{ book.title }}</p>
{% endfor %}
{{ page_obj.page_html|safe }}
# 后端
book_list = models.Book.objects.all()
current_page = request.GET.get("page",1)
all_count = book_list.count()
page_obj = Pagination(current_page=current_page,all_count=all_count,per_page_num=10,pager_count=5)
page_queryset = book_list[page_obj.start:page_obj.end]
分页器模板代码
class Pagination(object):
def __init__(self, current_page, all_count, per_page_num=2, pager_count=11):
"""
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 用法:
queryset = model.objects.all()
page_obj = Pagination(current_page,all_count)
page_data = queryset[page_obj.start:page_obj.end]
获取数据用page_data而不再使用原始的queryset
获取前端分页样式用page_obj.page_html
"""
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)
utils文件中mypage.py
from app01.utils.mypage import Pagination
def book(request):
book_list = models.Book.objects.all()
current_page = request.GET.get("page",1)
all_count = book_list.count()
page_obj = Pagination(current_page=current_page,all_count=all_count,per_page_num=10)
page_queryset = book_list[page_obj.start:page_obj.end] return render(request,'booklist.html',locals())
views.py
<body>
<div class="container">
<div class="row">
<div class="col-md-8 col-md-offset-2">
{% for book in page_queryset %}
<p>{{ book.title }}</p>
{% endfor %}
{{ page_obj.page_html|safe }}
</div>
</div>
</div>
</body>
前端
Django 序列化组件
什么时候用
后端想直接将实例化出来的数据对象直接发送给客户端，那么这个时候，就可以用Django给我们提供的序列化方式
# 后端:
def ser(request):
#拿到用户表里面的所有的用户对象
user_list=models.User.objects.all()
#导入内置序列化模块
from django.core import serializers
#调用该模块下的方法，第一个参数是你想以什么样的方式序列化你的数据
ret=serializers.serialize('json',user_list)
return render(request,'index.html',locals())
# 前端得到:
[{"model": "app01.user","pk": 1,"fields":
{"username": "jason","age": 18,"gender": 1}
}......]
bulk_create 批量插入数据(高效)
l = []
for i in range(10000):
l.append(models.Book2(name='第%s本书'%i))
models.Book2.objects.bulk_create(l) # 批量插入数据
choices字段参数
为什么用
1.对于类型性别,假否,婚否的字段,有固定字段数据的字段可以用choices参数
2.节省空间,因为存的是数字
如何使用
# models.py文件中:
class User(models.Model):
username = models.CharField(max_length=32)
age = models.IntegerField()
choices = (
(1,'男'),(2,'女'),(3,'其他')
)
gender = models.IntegerField(choices=choices) # 指定choices参数
"""
1 存choice里面罗列的数字与中文对应关系
print(user_obj.get_gender_display())
只要是choices字段 在获取数字对应的注释 固定语法
get_字段名_display()
2 存没有罗列出来的数字
不会报错 还是展示数字
"""
# views.py文件中
def userlist(request):
user_obj = models.User.objects.filter(pk=1).first()
gender = user_obj.get_gender_display() # 得到对应的性别注释,如'男'