MVVM屬性不更新

Question

我有產權更新

奇怪的問題

我的模型看起來像

using GalaSoft.MvvmLight.Messaging; 
using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Linq; 
using System.Text; 
using TestSome.DataType; 
using TestSome.MessageInfrastructure; 
using TestSome.WorkingWithNode; 

namespace TestSome.Model 
{ 
    class CentralModel 
    { 
     private BalanceTest someTest; 
     public BalanceTest SomeTest 
     { 
      get { return someTest; } 
      set { someTest = value; } 
     } 
     public void ListenBalance() 
     { 
      SocketHandler.Socket.Handle.Add("balance", (m) => 
      { 
       try 
       { 
        BalanceTest bt = m.Message.Json.GetFirstArgAs<BalanceTest>(); 
        SomeTest = bt; 
        Messenger.Default.Send(new BalanceCommunicator { TestBalance = bt }, "Token"); 
       } 
       catch (Exception ex) 
       { 
        System.Windows.MessageBox.Show(ex.Message.ToString()); 
       } 
      }); 
     } 
    } 
} 

我的視圖模型看起來像

public class BalanceViewModel : ViewModelBase 
{ 
    private BalanceTest some; 
    public BalanceTest Some 
    { 
     get { return some; } 
     set { some = value; RaisePropertyChanged("Some"); } 
    } 
    private CentralModel CM; 
    public BalanceViewModel() 
     { 
      try 
      { 
       CM = new CentralModel(); 
       CM.ListenBalance(); 
       Some = CM.SomeTest; 
      } 
      catch (Exception ex) 
      { 
       System.Windows.MessageBox.Show(ex.Message.ToString()); 
      } 
     } 

和XAML看起來像

<UserControl x:Class="TestSome.Views.BalanceView" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
     xmlns:Test="clr-namespace:TestSome.Model" 
     mc:Ignorable="d" 
     d:DesignHeight="300" d:DesignWidth="300"> 
<UserControl.Resources> 
    <Test:CentralModel x:Key="CentralMode"></Test:CentralModel> 
</UserControl.Resources> 
<Expander ExpandDirection="Right"> 
<StackPanel Orientation="Horizontal"> 

     <Label Content="{Binding SomeTest.Balance,Source={StaticResource CentralMode},Mode=TwoWay}"></Label> 
</StackPanel> 
</Expander> 

爲什麼不更新？

Answer 1

我建議你實現你的CentralModel類的event和處理程序在你的BalanceViewModel，爲了交流新數據向上。

在CentralModel類：

/// <summary> 
/// Raised when a new balance is received. 
/// </summary> 
public event EventHandler<EventArgs> NewBalanceEvent; 

public void ListenBalance() 
{ 
    SocketHandler.Socket.Handle.Add("balance", (m) => 
    { 
     try 
     { 
      BalanceTest bt = m.Message.Json.GetFirstArgAs<BalanceTest>(); 
      SomeTest = bt; 
      Messenger.Default.Send(new BalanceCommunicator { TestBalance = bt }, "Token"); 

      // Raise the event 
      EventHandler<EventArgs> RaiseNewBalanceEvent = NewBalanceEvent; 
      if (null != RaiseNewBalanceEvent) 
      { 
       RaiseNewBalanceEvent(this, EventArgs.Empty); 
      } 
     } 
     catch (Exception ex) 
     { 
      System.Windows.MessageBox.Show(ex.Message.ToString()); 
     } 
    }); 
} 

而在你BalanceViewModel類掛鉤事件：

private void NewBalanceEventHandler(Object sender, EventArgs args) 
{ 
    // This will trigger the property changed event. 
    Some = CM.SomeTest; 
} 

public BalanceViewModel() 
{ 
    try 
    { 
     CM = new CentralModel(); 
     CM.ListenBalance(); 
     Some = CM.SomeTest; 

     // Attach to the NewBalance event 
     // Note: you should detatch it again (with -=) when you've finished with it. 
     CM.NewBalanceEvent += NewBalanceEventHandler; 
    } 
    catch (Exception ex) 
    { 
     System.Windows.MessageBox.Show(ex.Message.ToString()); 
    } 
} 

現在，每當拉姆達在SocketHandler.Socket.Handle.Add被調用時，CentralModel提高了NewBalanceEvent，這依次（通過框架）調用BalanceViewModel的事件處理程序委託，並且Some屬性得到更新。

編輯

此外，this answer，由fix-likes-coding提供的是正確的：你需要綁定到View中的正確的屬性。

Answer 2

您不會在SomeTest屬性上提升RaisePropertyChanged("SomeTest")。它爲什麼會起作用？ :)

Answer 3

您需要綁定到你的BalanceViewModel的Some，而不是到CentralModel

<Label Content="{Binding Path=Some.Balance,Mode=TwoWay}"></Label>