private readonly IPropertyMappingService _propertyMappingService; //依赖与抽象而不是实现，这里依赖注入和下面的容器都必须是接口类型
public CompanyRepository(Restful_DbContext context, IPropertyMappingService propertyMappingService)
{
_context = context ?? throw new ArgumentNullException(nameof(context));
_propertyMappingService = propertyMappingService ?? throw new ArgumentNullException(nameof(propertyMappingService));
}
//再次犯错，这里必须要注入接口类型propertyMappingServiceForTask，容器里必须是接口类型或者抽象服务类
public EmployeeTaskRepository(Restful_DbContext context, IPropertyMappingServiceForTask propertyMappingServiceForTask)
{
_context = context ?? throw new ArgumentNullException(nameof(context));
_propertyMappingServiceForTask = propertyMappingServiceForTask ?? throw new ArgumentNullException(nameof(propertyMappingServiceForTask));
}
