（提问复习为主）
一、Django请求的生命周期
          路由系统 -> 视图函数(获取模板+数据=》渲染) -> 字符串返回给用户
 
 
二、路由系统
          /index/                        ->  函数或类.as_view()
          /detail/(\d+)                 ->  函数(参数) 或 类.as_view()（参数）
          /detail/(?P<nid>\d+)   ->  函数(参数) 或 类.as_view()（参数）
          /detail/                        ->  include("app01.urls")
          /detail/    name='a1'   ->  include("app01.urls")
                                      - 视图中：reverse
                                      - 模板中：{% url "a1" %}
 
 
三、视图
     FBV：函数
          def index(request,*args,**kwargs):
               ..
 
     CBV：类
          class Home(views.View):
 
               def get(self,reqeust,*args,**kwargs):
                    ..
 
     获取用户请求中的数据：
          request.POST.get
          request.GET.get
          reqeust.FILES.get()
          # checkbox,
          ........getlist()
          request.path_info
          文件对象 = reqeust.FILES.get()
          文件对象.name
          文件对象.size
          文件对象.chunks()
 
          # <form 特殊的设置></form>
 
     给用户返回数据：
          render(request, "模板的文件的路径", {'k1': [1,2,3,4],"k2": {'name': '张扬','age': 73}})
          redirect("URL")
          HttpResponse(字符串)
 
 
四、模板语言
          render(request, "模板的文件的路径", {'obj': 1234, 'k1': [1,2,3,4],"k2": {'name': '张扬','age': 73}})
 
     <html>
     <body>
          <h1> {{ obj }} </h1>
          <h1> {{ k1.3 }} </h1>
          <h1> {{ k2.name }} </h1>
          {% for i in k1 %}
               <p> {{ i }} </p>
          {% endfor %}
 
          {% for row in k2.keys %}
               {{ row }}
          {% endfor %}
 
          {% for row in k2.values %}
               {{ row }}
          {% endfor %}
 
          {% for k,v in k2.items %}
               {{ k }} - {{v}}
          {% endfor %}
     </body>
     </html>
 
五、ORM
     a. 创建类和字段
          class User(models.Model):
               age = models.IntergerFiled()
               name = models.CharField(max_length=10)#字符长度
          
          #生成数据表
          Python manage.py makemigrations
          python manage.py migrate
 
          —切记：一定要在 settings.py 中注册APP
 
     b. 数据库操作
          增
               models.User.objects.create(name='qianxiaohu',age=18)
               dic = {'name': 'xx', 'age': 19}
               models.User.objects.create(**dic)
 
 
               obj = models.User(name='qiangxiaohu',age=18)
               obj.save()
          删
               models.User.objects.filter(id=1).delete()
          改
               models.User.objects.filter(id__gt=1).update(name='alex',age=84)
               dic = {'name': 'xx', 'age': 19}
               models.User.objects.filter(id__gt=1).update(**dic)
          查
               models.User.objects.filter(id=1,name='root')
               models.User.objects.filter(id__gt=1,name='root')
               models.User.objects.filter(id__lt=1)
               models.User.objects.filter(id__gte=1)
               models.User.objects.filter(id__lte=1)
 
               models.User.objects.filter(id=1,name='root')
               dic = {'name': 'xx', 'age__gt': 19}
               models.User.objects.filter(**dic)
 
               v1 = models.Business.objects.all()
               # QuerySet ,内部元素都是对象
               # QuerySet ,内部元素都是字典
               v2 = models.Business.objects.all().values('id','caption')
               # QuerySet ,内部元素都是元组
               v3 = models.Business.objects.all().values_list('id','caption')
 
               # 获取到的一个对象，如果不存在就报错
               models.Business.objects.get(id=1)
               对象或者None = models.Business.objects.filter(id=1).first()
 
 
               外键：
                    v = models.Host.objects.filter(nid__gt=0)
                    v[0].b.caption  ---->  通过.符号进行跨表
 
 
          外键：
               class UserType(models.Model):
                    caption = models.CharField(max_length=32)
                id  caption
               # 1，普通用户
               # 2，VIP用户
               # 3， 游客
 
               class User(models.Model):
                    age = models.IntergerFiled()
                    name = models.CharField(max_length=10)#字符长度
                    # user_type_id = models.IntergerFiled() # 约束，
                    user_type = models.ForeignKey("UserType",to_field='id') # 约束，
 
                 name age  user_type_id     
               # 张扬  18     3
               # 张A扬 18     2
               # 张B扬 18     2
 
张扬：
     position:fixed absolute relative
 
 
六、Ajax
 
          $.ajax({
               url: '/host',
               type: "POST",
               data: {'k1': 123,'k2': "root"},
               success: function(data){
                    // data是服务器端返回的字符串
                    var obj = JSON.parse(data);
               }
          })
 
 
          建议：永远让服务器端返回一个字典
 
          return HttpResponse(json.dumps(字典))
 
 
七、ORM多对多：
    创建多对多：
          方式一：自定义关系表
               class Host(models.Model):
                    nid = models.AutoField(primary_key=True)
                    hostname = models.CharField(max_length=32,db_index=True)
                    ip = models.GenericIPAddressField(protocol="ipv4",db_index=True)
                    port = models.IntegerField()
                    b = models.ForeignKey(to="Business", to_field='id')
               # 10？
               class Application(models.Model):
                    name = models.CharField(max_length=32)
               # 2
               class HostToApp(models.Model):
                    hobj = models.ForeignKey(to='Host',to_field='nid')
                    aobj = models.ForeignKey(to='Application',to_field='id')
 
               # HostToApp.objects.create(hobj_id=1,aobj_id=2）
 
 
          方式二：自动创建关系表
               class Host(models.Model):
                    nid = models.AutoField(primary_key=True)
                    hostname = models.CharField(max_length=32,db_index=True)
                    ip = models.GenericIPAddressField(protocol="ipv4",db_index=True)
                    port = models.IntegerField()
                    b = models.ForeignKey(to="Business", to_field='id')
               # 10？
               class Application(models.Model):
                    name = models.CharField(max_length=32)
                    r = models.ManyToManyField("Host")
 
               无法直接对第三张表进行操作
 
               obj = Application.objects.get(id=1)
               obj.name
 
               # 第三张表操作
               obj.r.add(1)
               obj.r.add(2)
               obj.r.add(2,3,4)
               obj.r.add(*[1,2,3,4]) 
               obj.r.remove(1)
               obj.r.remove(2,4)
               obj.r.remove(*[1,2,3])
               obj.r.clear()
               obj.r.set([3,5,7]) #只保留设置数据
 
               # 所有相关的主机对象“列表” QuerySet
               obj.r.all()