Django基础之三（类视图）

类视图

简介

视图是一个可调用的对象，它接收一个请求然后返回一个响应，这个可调用对象可以不只是函数，Django提供一些可以用作视图的类
基于类的视图使用Python 对象实现视图，它提供除函数视图之外的另外一种方式

view

• 属性

http_method_names：添加未知的请求方法

• 方法

as_view()：将类视图转换成可被调用的函数视图
dispatch()： 根据请求去匹配http_method_names下的对应函数去处理请求
http_method_not_allowed()：返回405错误

• 实例

from django.views import View
class IndexView(View):
    http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace','list']
    def get(self,request,*args,**kwargs):
        return HttpResponse(IndexView)

    def post(self,request,*args,**kwargs):
        data = request.POST
        return HttpResponse(data)
    #需要将list方法加入 http_method_names，否则会经过，dispatch，http_method_not_allowed()：返回405错误
    def list(self,request,*args,**kwargs):
        return HttpResponse("ListView")
请求方式：
In [27]: import requests                                                                
In [28]: url = 'http://192.168.33.10:8080/dashboard/index/'                             
In [29]: res = requests.request('list',url)                                             
In [30]: res.content                                                                    
Out[30]: b'ListView'

数据分页

基于sql切片的方式分页

数据准备

In [3]: from django.contrib.auth.models import User
In [4]: for n in range(1,101): 
...:     User.objects.create_user('wanghui-{}'.format(n),'wanghui-{}@alibaba.com'.format(n),'123456') 
In [5]: User.objects.all()[1:10]      

类视图

class UserView(View):
    #http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace','list']
    def get(self,request,*args,**kwargs):
      #展示数据
        # queryset = User.objects.all()
        # return HttpResponse(queryset)
        try:
            page = int(request.GET.get('page'))
        except:
            page = 1
        if page < 1:
            page = 1
        per = 10
        end = page * per
        start = end - per
        queryset = User.objects.all()[start:end]
        data = [{"id":user.id,"username":user.username,"email":user.email} for user in queryset]
        return JsonResponse(data,safe=False)

基于Paginator对象的分页

class Paginator(object_list, per_page, orphans=0, allow_empty_first_page=True)
属性
- Paginator.count 所有页面的objects总数
- Paginator.num_pages 页面总数
- Paginator.page_range 页码的范围，从1开始，例如[1, 2, 3, 4]
方法
- Paginator.page(number) 返回一个page对象,number， 当前显示的是第几页

Page对象

class Page(object_list, number, paginator)

方法
- Page.has_next() 如果有下一页，返回True
- Page.has_previous() 如果有上一页，返回 True
- Page.has_other_pages() 如果有上一面或下一页，返回True
- Page.next_page_number() 返回下一页的页码.如果不存在,抛出InvalidPage异常
- Page.previous_page_number() 返回上一页的页码.如果不存在,抛出InvalidPage异常
- Page.start_index() 返回当前页上的第一个对象，相对于分页列表的所有对象的序号
- Page.end_index() 返回当前页上的最后一个对象，相对于分页列表的所有对象的序号

创建用户小例子

from django.core.paginator import Paginator
class UserViewV2(View):
    def get(self,request,*args,**kwargs):
        queryset = User.objects.all()
        paginator = Paginator(queryset,10)
        try:
            page = int(request.GET.get("page"))
        except:
            page = 1
        if page < 1:
            page = 1
        page = paginator.page(page)
        data = [{"id":user.id,"username":user.username,"email":user.email} for user in page.object_list]
        return JsonResponse(data,safe=False)

    def post(self,request,*args,**kwargs):
        username = request.POST.get("username")
        userpass = request.POST.get("userpass")
        email = request.POST.get('email')
        if not username or userpass or not email:
            return JsonResponse({"errormsg":"参数有误！"})
        user = User.objects.create(username,email,userpass)
        return JsonResponse({"id":user.id,"username":user.username,"email":user.email})

请求方式

In [1]: import requests                                                                     
In [2]: url = "http://192.168.33.10:8080/dashboard/userview/"                
In [3]: data = {}                                                                                         
In [4]: data["username"] = "zhangsan"                                                     
In [5]: data["userpass"] = '123456'                                                           
In [6]: data["email"] = "[e-mail]"                                     
In [7]: requests.post(url,data)                                                                 
Out[7]: <Response [200]>