我第一次在wpf mvvm中工作，并且在“现实生活中的问题”中遇到了一些问题
我有一个带有视图的ViewModel，从那里我必须打开第二个视图（带有它的ViewModel，它将有一个对象列表），在这里，我必须选择一个对象，将其返回到第一个ViewModel，我将在哪里使用它。
我正在使用一种简单的方法来打开第二个窗口，我知道我稍微破坏了mvvm模式
public object ShowDialog<TView, TViewModel>(TViewModel dataContext) where TView : IWindow, new() where TViewModel : BaseViewModel<TViewModel>
{
//Instancio la vista.
TView view = new TView();
WindowService wnd = new WindowService(view);
dataContext?.SetWindowService(wnd);
view.DataContext = dataContext;
view.ShowDialog();
return dataContext;
}
然后在ViewModel中，我像这样打开第二页
WindowService.ShowDialog<ChooseOneCat, ChooseOneCatViewModel>(null);
然后在ChooseOneCat ViewModel中，让用户选择以后必须返回的类别
这是我的问题，如何将那个对象赋予第一个视图模型？
Pd：我不使用任何其他框架。
谢谢！
答案 0 :(得分：0)
我设法使用messenger解决了问题，具体来说，是在Dalstroem response
中找到的一种实现源代码：
using System; using System.Collections.Concurrent; using System.Collections.Generic; using System.Linq; namespace Application.Messaging { public class Messenger { private static readonly object CreationLock = new object(); private static readonly ConcurrentDictionary<MessengerKey, object> Dictionary = new ConcurrentDictionary<MessengerKey, object>(); #region Default property private static Messenger _instance; /// <summary> /// Gets the single instance of the Messenger. /// </summary> public static Messenger Default { get { if (_instance == null) { lock (CreationLock) { if (_instance == null) { _instance = new Messenger(); } } } return _instance; } } #endregion /// <summary> /// Initializes a new instance of the Messenger class. /// </summary> private Messenger() { } /// <summary> /// Registers a recipient for a type of message T. The action parameter will be executed /// when a corresponding message is sent. /// </summary> /// <typeparam name="T"></typeparam> /// <param name="recipient"></param> /// <param name="action"></param> public void Register<T>(object recipient, Action<T> action) { Register(recipient, action, null); } /// <summary> /// Registers a recipient for a type of message T and a matching context. The action parameter will be executed /// when a corresponding message is sent. /// </summary> /// <typeparam name="T"></typeparam> /// <param name="recipient"></param> /// <param name="action"></param> /// <param name="context"></param> public void Register<T>(object recipient, Action<T> action, object context) { var key = new MessengerKey(recipient, context); Dictionary.TryAdd(key, action); } /// <summary> /// Unregisters a messenger recipient completely. After this method is executed, the recipient will /// no longer receive any messages. /// </summary> /// <param name="recipient"></param> public void Unregister(object recipient) { Unregister(recipient, null); } /// <summary> /// Unregisters a messenger recipient with a matching context completely. After this method is executed, the recipient will /// no longer receive any messages. /// </summary> /// <param name="recipient"></param> /// <param name="context"></param> public void Unregister(object recipient, object context) { object action; var key = new MessengerKey(recipient, context); Dictionary.TryRemove(key, out action); } /// <summary> /// Sends a message to registered recipients. The message will reach all recipients that are /// registered for this message type. /// </summary> /// <typeparam name="T"></typeparam> /// <param name="message"></param> public void Send<T>(T message) { Send(message, null); } /// <summary> /// Sends a message to registered recipients. The message will reach all recipients that are /// registered for this message type and matching context. /// </summary> /// <typeparam name="T"></typeparam> /// <param name="message"></param> /// <param name="context"></param> public void Send<T>(T message, object context) { IEnumerable<KeyValuePair<MessengerKey, object>> result; if (context == null) { // Get all recipients where the context is null. result = from r in Dictionary where r.Key.Context == null select r; } else { // Get all recipients where the context is matching. result = from r in Dictionary where r.Key.Context != null && r.Key.Context.Equals(context) select r; } foreach (var action in result.Select(x => x.Value).OfType<Action<T>>()) { // Send the message to all recipients. action(message); } } protected class MessengerKey { public object Recipient { get; private set; } public object Context { get; private set; } /// <summary> /// Initializes a new instance of the MessengerKey class. /// </summary> /// <param name="recipient"></param> /// <param name="context"></param> public MessengerKey(object recipient, object context) { Recipient = recipient; Context = context; } /// <summary> /// Determines whether the specified MessengerKey is equal to the current MessengerKey. /// </summary> /// <param name="other"></param> /// <returns></returns> protected bool Equals(MessengerKey other) { return Equals(Recipient, other.Recipient) && Equals(Context, other.Context); } /// <summary> /// Determines whether the specified MessengerKey is equal to the current MessengerKey. /// </summary> /// <param name="obj"></param> /// <returns></returns> public override bool Equals(object obj) { if (ReferenceEquals(null, obj)) return false; if (ReferenceEquals(this, obj)) return true; if (obj.GetType() != GetType()) return false; return Equals((MessengerKey)obj); } /// <summary> /// Serves as a hash function for a particular type. /// </summary> /// <returns></returns> public override int GetHashCode() { unchecked { return ((Recipient != null ? Recipient.GetHashCode() : 0) * >397) ^ (Context != null ? Context.GetHashCode() : 0); } } } } }