Django-admin流程

- 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：将注册类添加到 _registry中 
                    _registry = {  
                        key是传进来的model   value:是ModelAdmin的对象，传了两个参数
                        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()   #是动态的
                    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():
                        model_class是一个类
                        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 )
            

参考博客1：http://www.cnblogs.com/wupeiqi/articles/7444717.html 

参考博客2：http://www.cnblogs.com/haiyan123/p/8034430.html