波苏斯和多个的ViewModels指向相同POCO？

问题描述

一个人怎么会去处理这样的情况？具有具有到相同POCO对象的引用多个视图模型。视图模型A更新的POCO ...现在视图模型B需要知道这个不知何故？

How would one go about handling a situation like this? Having more than one ViewModel having a reference to the same POCO object. ViewModel A updates the POCO... now ViewModel B needs to know about this somehow?

推荐答案

假设你的POCO不能实施 INotifyPropertyChanged的，你可以使用当POCO改变格局，以提醒其他视图模型：

Assuming that your POCO can't implement INotifyPropertyChanged, you could use a mediator pattern to alert other view models when a POCO is changed:

public interface ICareWhenAModelChanges<T>
{
    void ModelUpdated(T updatedModel);
}

public class ModelChangeMediator<T>
{
    private List<ICareWhenAModelChanges<T>> _listeners = new List<ICareWhenAModelChanges<T>>();

    public void Register(ICareWhenAModelChanges<T> listener)
    {
        _listeners.Add(listener);
    }

    public void NotifyThatModelIsUpdated(T updatedModel)
    {
        foreach (var listener in _listeners) listener.ModelUpdated(updatedModel);
    }
}

您的视图模型则可以实现 ICareWhenAModelChanges< T> 接口，与调解员的共享实例注册本身（或者通过一个单身，或者更好，某种DI / IoC框架的收购），做任何它需要在 ModelUpdated 法

Your view model can then implement the ICareWhenAModelChanges<T> interface, register itself with a shared instance of the mediator (acquired through either a singleton or, better, some kind of DI/IoC framework) and do whatever it needs to in the ModelUpdated method

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