选项模式 - Interface/Abstract 属性

Question

我想将以下对象与 ServiceCollection 中的 appsettings.json 数据绑定，但是我无法更改设计class 或界面：

public class TransferOptions :ITransferOptions 
{
   public IConnectionInfo Source {get;set;}
   public IConnectionInfo Destination {get;set;}
}

public class ConnectionInfo : IConnectionInfo
{
   public string UserName{get;set;}
   public string Password{get;set;}
}

public interface ITransferOptions
{
   IConnectionInfo Source {get;set;}
   IConnectionInfo Destination {get;set;}
}

public interface IConnectionInfo
{
   string UserName{get;set;}
   string Password{get;set;}
}

这是我在appsettings.json

中的数据

{
"TransferOptions":{
    "Source ":{
                 "UserName":"USERNAME",
                 "Password":"PASSWORD"
              },
    "Destination":{
                 "UserName":"USERNAME",
                 "Password":"PASSWORD"
              }
   }
}

这是我在服务提供商上的配置：

var provider=new ServiceCollection()
.Configure<TransferOptions>(options => _configuration.GetSection("TransferOptions").Bind(options))
.BuildServiceProvider();

这是我出错的部分

Cannot create instance of type 'IConnectionInfo' because it is either abstract or an interface:

var transferOptions =_serviceProvider.GetService<IOptions<TransferOptions>>()

Answer 1

An interface cannot be instantiated directly.

因此，如果您不能更改 class' 设计 - 即使用 ConnectionInfo 的具体实现 - 我想您可以实例化 ConnectionInfo class 并将其分配给IConnectionInfo 接口如下：

public class TransferOptions : ITransferOptions 
{
   public IConnectionInfo Source { get; set; } = new ConnectionInfo();
   public IConnectionInfo Destination { get; set; } = new ConnectionInfo();
}

Answer 2

由于接口和规定的限制，您需要自己构建选项成员

var services = new ServiceCollection();

IConnectionInfo source = _configuration.GetSection("TransferOptions:Source").Get<ConnectionInfo>();
IConnectionInfo destination = _configuration.GetSection("TransferOptions:Destination").Get<ConnectionInfo>();

services.Configure<TransferOptions>(options => {
    options.Source = source;
    options.Destination = destination;
});

var provider = services.BuildServiceProvider();

选项模式 - Interface/Abstract 属性

Options pattern - Interface/Abstract property

c#

.net-core

.net-core-configuration

servicecollection

An interface cannot be instantiated directly.