在Messenger类中使用令牌的正确方法是什么?

本文介绍了在Messenger类中使用令牌的正确方法是什么?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在使用MVVM Light Toolkit的3.0.3.19版本.

I am using version 3.0.3.19 of the MVVM Light Toolkit.

来自 blog.galasoft.ch/archive/2010/03/16/whatrsquos-new-in-mvvm-light-v3.aspx :

现在可以使用令牌通过Messenger发送邮件.

Messages can now be sent through the Messenger with a token.

• 要发送带有令牌的消息，请使用重载Send(TMessage消息，对象令牌)方法.

• To send a message with token, use the method overload Send(TMessage message, object token).

要接收带有令牌的消息，请使用方法Register(对象收件人，对象令牌，Action操作)或Register(对象收件人， 对象令牌，bool receiveDerivedMessagesToo，操作操作)

To receive a message with token, use the methods Register(object recipient, object token, Action action) or Register(object recipient, object token, bool receiveDerivedMessagesToo, Action action)

令牌可以是简单值(int，字符串等)或实例 一堂课该邮件不会传递给已注册的收件人 带有其他令牌或完全没有令牌.

The token can be a simple value (int, string, etc…) or an instance of a class. The message is not delivered to recipients who registered with a different token, or with no token at all.

根据上述文档，我已经在ViewModel A中尝试了以下方法:

According to the documentation above, I have tried the following in ViewModel A:

Messenger.Default.Send(new NotificationMessage("message"), "token");

在ViewModel B中附带以下内容:

Along with the following in ViewModel B:

Messenger.Default.Register<NotificationMessage>(this, "token", (msg) => Console.WriteLine(msg.Notification));

但是，永远不会执行该回调.我在做什么错了?

However, the callback is never executed. What am I doing wrong?

推荐答案

我的ViewModelLocator在ViewModel B之前初始化ViewModelA.换句话说，该消息已由ViewModel A正确发送，但是ViewModel B尚未真正发送收到.

My ViewModelLocator was initializing ViewModel A before ViewModel B. In other words, the message was being sent properly by ViewModel A, but ViewModel B was not yet around to actually receive it.

我在ViewModelLocator中更改了初始化顺序，问题得以解决.此外，请验证Messenger是否可以使用String以外的其他类型的令牌.

I changed the order of initialization in the ViewModelLocator and the problem was solved. Also, verified that the Messenger worked with tokens of other types besides String.