Django Admin流程

            
类复习：

    class Base(object):
        def __init__(self,val):
            self.val = val
        def func(self):
            self.test()
            print(self.val)
        def test(self):
            print('Base.test')
    class Foo(Base):
        def test(self):
            print('Foo.test')

    class Bar(object):
        def __init__(self):
            self._registry = {}
        def regiter(self,a,b=None):
            if not b:
                b = Base
            self._registry[a] = b(a) # 函数、类、对象
    
    obj = Bar()
    obj.regiter(1,Foo)
    obj.regiter(2)
    obj._registry[1].func() # Foo的对象
    obj._registry[2].func() # Base对象


            

- admin

    路由规则：
        /admin/app01/role/           查看角色列表
        /admin/app01/role/add/       添加角色
        /admin/app01/role/2/change/  编辑
        /admin/app01/role/2/delete/  删除
        
        
        /admin/app01/userinfo/           
        /admin/app01/userinfo/add/      
        /admin/app01/userinfo/1/change/
        /admin/app01/userinfo/1/delete/
        

- Django启动
    
- admin流程

    - 执行已经注册app的admins.py文件
    - 创建AdminSite类的admin.site对象 执行对象register()方法, 把数据赋值到self.registry={}中
        - self._registry[model] = ModelAdmin(model, self)

    - 进入urls.py 执行admin.site.urls方法
        - 返回一个元组 元组的第一个元素是列表

    
    - 所以生成url的时候经历了两个类 一个是admin.site类  admin.site会调用model_admin类中的urls


            
- admin源码流程

    a. 运行程序，找到每一个app中的 admin.py 文件，并加载
        - app01.admin.py 
            - 创建admin.site中的对象
            - 执行对象的 register方法，目的：讲注册类添加到 _registry中 
                _registry = {
                    models.Role: ModelAdmin(models.Role,admin.site),
                    models.UserInfo: ModelAdmin(models.UserInfo,admin.site)
                    models.UserType: ModelAdmin(models.UserType,admin.site)
                }
            
        - app02.admin.py
            - 用app01.admin中创建那个admin.site对象
            - 执行对象的 register方法，目的：讲注册类添加到 _registry中 
                _registry = {
                    models.Role: ModelAdmin(models.Role,admin.site),
                    models.UserInfo: ModelAdmin(models.UserInfo,admin.site)
                    models.UserType: ModelAdmin(models.UserType,admin.site)
                    models.Article: ModelAdmin(models.Article,admin.site)
                }
    
        admin.site是一个对象（单例模式创建），其中封装了： 
            _registry = {
                models.Role: ModelAdmin(models.Role,admin.site),
                models.UserInfo: ModelAdmin(models.UserInfo,admin.site)
                models.UserType: ModelAdmin(models.UserType,admin.site)
                models.Article: ModelAdmin(models.Article,admin.site)
            }
    b. urls.py 

        再次调用 admin.site 对象的 urls属性：
            urlpatterns = [
                url(r'^admin/', admin.site.urls),
            ]
        
        class ModelAdmin(object):
            def __init__(self,model_class,site):
                self.model_class = model_class
                self.site = site 
                
            def changelist_view(self,request):
                data_list = self.model_class.objects.all()
                return HttpResponse('列表页面')

            def add_view(self,request):
                return HttpResponse('添加页面')


            def delete_view(self,request,nid):
                return HttpResponse('删除页面')

            def change_view(self,request,nid):
                return HttpResponse('修改页面')
            
            def get_urls(self):
                 urlpatterns = [
                    url(r'^$', self.changelist_view),
                    url(r'^add/$', self.add_view),
                    url(r'^(.+)/delete/$', self.delete_view),
                    url(r'^(.+)/change/$', self.change_view),
                ]
                return urlpatterns
            
            @property 
            def urls(self):
                return self.get_urls()
            
        
        class AdminSite(object):
            def __init__(self):
                self._registry = {}
                
            def register(self,model_class,model_admin):
                self._registry[model_class] = model_admin(model_class,self)
            
            def get_urls(self):
                """
                models.Role: ModelAdmin(models.Role,admin.site),
                models.UserInfo: ModelAdmin(models.UserInfo,admin.site)
                models.UserType: ModelAdmin(models.UserType,admin.site)
                models.Article: ModelAdmin(models.Article,admin.site)
                """
                url_list = []
                for model_class,model_admin in self._registry.items():
                    app_name = model_class._meta.app_label
                    model_name = model_class._meta.model_name 
                    url_list += [
                        url('%s/%s' %(app_name,model_name,), include(model_admin.urls))
                    ]
                    
                return url_list
                    
            
            @property
            def urls(self):
                return (self.get_urls(), None,None )