在 Autofac "property injection" / ASP.NET Webforms Application 中解析 2 个相同类型的属性

Question

我有一个 BasePage class，它有两个相同依赖类型的属性，我找不到使用 Autofac

提供所需参数的方法

我尝试注册类型，两个 BasePage 属性现在都指向同一个最后注册的组件，即 FaxSender，我在函数 TryGetDeclaringProperty 添加了一个断点，它工作正常并检查 BasePage [的属性名称=29=].

[更新示例]

public class BasePage : System.Web.UI.Page
{
    public ISender EmailSender { get; set; }
    public ISender FaxSender { get; set; }
}

public class EmailSender : ISender
{
    private readonly SmtpClient _smtpClient;

    public EmailSender(SmtpClient smtpClient)
    {
        _smtpClient = smtpClient;
    }
    public void Send(INotification notification)
    {
        //...
    }
}

public class FaxSender : ISender
{
    private readonly SmtpClient _smtpClient;

    public FaxSender(SmtpClient smtpClient)
    {
        _smtpClient = smtpClient;
    }
    public void Send(INotification notification)
    {
        //...
    }
}

在Global.asax.cs

  var emailSmtp = new SmtpClient
        {
            ...
        };

        var emailSender = new EmailSender(emailSmtp);

        var faxSmtp = new SmtpClient
        {
            ...
        };

        var faxSender = new FaxSender(faxSmtp);

        var builder = new ContainerBuilder();

//--------------------------------
        builder.RegisterType<BasePage>()
            .WithProperties(new Parameter[]{
                new NamedPropertyParameter("EmailSender", emailSender),
                new NamedPropertyParameter("FaxSender", faxSender),
            });
 //--------------------------------  

    //OR

//--------------------------------

builder.RegisterType<EmailSender>()
            .Named<ISender>("email")
            .WithParameter("smtpClient", emailSmtp);
        builder.RegisterType<FaxSender>()
            .Named<ISender>("fax")
            .WithParameter("smtpClient", faxSmtp);

        builder.RegisterType<BasePage>()
            .AsSelf()
            .WithProperties(new Parameter[] {
                new ResolvedParameter(
                    (pi, c) => {
                        PropertyInfo ppi = null;
                        if (pi.TryGetDeclaringProperty(out ppi)) {
                            return ppi.Name == "EmailSender";
                        } else {
                            return false;
                        }
                    },
                    (pi, c) => c.ResolveNamed<ISender>("email")),
                new ResolvedParameter(
                    (pi, c) => {
                        PropertyInfo ppi = null;
                        if (pi.TryGetDeclaringProperty(out ppi)) {
                            return ppi.Name == "FaxSender";
                        } else {
                            return false;
                        }
                    },
                    (pi, c) => c.ResolveNamed<ISender>("fax"))
            });

//--------------------------------
//and then

        var container = builder.Build();

        _containerProvider = new ContainerProvider(container);

        using (var scope = container.BeginLifetimeScope())
        {
            scope.Resolve<BasePage>();
        }

在Default.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
    //Object reference not set to an instance of an object.  [Exception in both cases]
    EmailSender.Send(new EmailNotification(...);

    FaxSender.Send(new FaxNotification(...));
}

Answer 1

由于 ASP.net webform 的架构，Page 实例不是由 Autofac 创建的，您无法为页面实例配置任何注册。在这种情况下不会使用 WithProperty 方法。

在您的情况下，一种解决方案是手动解决依赖关系。

在您的 BasePage 组件中

public ISender EmailSender
{
    get
    {
        var cpa = (IContainerProviderAccessor)this.Context.ApplicationInstance;
        return cpa.ContainerProvider.RequestLifetime.ResolveNamed<ISender>("email");
    }
}

另一个解决方案是使用 IIndex<TKey, TValue>。您可以只拥有一个包含所有 ISender 的属性，而不是拥有 2 个属性。

public IIndex<String, ISender> Senders {get; set; }

当您需要特定的发件人时，您可以通过

访问它

ISender emailSender = this.Senders["email"];

顺便说一句，如果您想要预期的行为，但对于由 Autofac 创建的实例，您应该使用 NamedPropertyParameter 而不是 NamedParameter。

// not working for webform !!! 
builder.RegisterType<BasePage>()
       .WithProperties(new Parameter[]{
           new NamedPropertyParameter("X", emailSender),
           new NamedPropertyParameter("Y", faxSender),
       });

如果你想通过依赖注入获取你的值，没有简单的方法可以做到。

Autofac 内部依赖于此扩展方法：

public static class ParameterInfoExtensions
{
  public static bool TryGetDeclaringProperty(this ParameterInfo pi, out PropertyInfo prop)
  {
    MethodInfo mi = pi.Member as MethodInfo;
    if (mi != (MethodInfo)null && mi.IsSpecialName 
        && mi.Name.StartsWith("set_", StringComparison.Ordinal) 
        && mi.DeclaringType != (Type)null)
    {
      prop = mi.DeclaringType.GetTypeInfo().GetDeclaredProperty(mi.Name.Substring(4));
      return true;
    }
    prop = null;
    return false;
  }
}

并且您可以通过这种方式将其与 ResolvedParameter 一起使用：

builder.RegisterType<EmailSender>() 
       .Named<ISender>("email")
       .WithParameter("smtpClient", emailSmtp);
builder.RegisterType<FaxSender>()
       .Named<ISender>("fax")
       .WithParameter("smtpClient", faxSmtp);

builder.RegisterType<BasePage>()
       .AsSelf()
       .WithProperties(new Parameter[] {
           new ResolvedParameter(
             (pi, c) => {
               PropertyInfo ppi = null;
               if (pi.TryGetDeclaringProperty(out ppi)) {
                 return ppi.Name == "SmtpClient";
               } else {
                 return false;
               }
             },
             (pi, c) => c.ResolveNamed<ISender>("email")),
           new ResolvedParameter(
             (pi, c) => {
               PropertyInfo ppi = null;
               if (pi.TryGetDeclaringProperty(out ppi)) {
                 return ppi.Name == "FaxClient";
               } else {
                 return false;
               }
           },
           (pi, c) => c.ResolveNamed<ISender>("fax"))
       });

在 Autofac "property injection" / ASP.NET Webforms Application 中解析 2 个相同类型的属性

Resolve 2 properties of the same type in Autofac "property injection" / ASP.NET Webforms Application

c#

asp.net

webforms

autofac