Question

以下代码基于此post：

我的问题：我无法看到我做错了什么让INotifyPropertyChanged导致textBox1绑定自动反映这个简单示例中的更改。

XAML。我添加了textBox2来确认属性正在改变

<StackPanel>
  <Button Margin="25" Content="Change the Value" Click="Button_Click"/>

  <Label Content="{}{Binding MyTextProperty}"/>
  <TextBox Name="textBox1" Text="{Binding MyTextProperty}"/>

  <Label Content="updated using code behind"/>
  <TextBox Name="textBox2" />
</StackPanel>

代码隐藏

Partial Class MainWindow

  Private vm = New ViewModel

  Sub New()
    InitializeComponent()
    DataContext = New ViewModel()
    textBox2.Text = vm.MyTextProperty
  End Sub

  Private Sub Button_Click(sender As Object, e As RoutedEventArgs)
    vm.ChangeTextValue()
    textBox2.Text = vm.MyTextProperty
  End Sub
End Class

视图模型

Public Class ViewModel
  Implements INotifyPropertyChanged

  Private _MyTextValue As String = String.Empty
  Public Property MyTextProperty() As String
    Get
      Return _MyTextValue
    End Get

    Set(ByVal value As String)
      _MyTextValue = value
      NotifyPropertyChanged("MyTextProperty")
    End Set
  End Property

  Public Sub New()
    MyTextProperty = "Value 0"
  End Sub

  Public Sub ChangeTextValue()
    MyTextProperty = Split(MyTextProperty)(0) & " " & Split(MyTextProperty)(1) + 1
  End Sub

  Public Event PropertyChanged As PropertyChangedEventHandler _
        Implements INotifyPropertyChanged.PropertyChanged

  Private Sub NotifyPropertyChanged(ByVal propertyName As String)
    RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
  End Sub
End Class

除了我所犯的任何错误之外，还有任何其他关于通过最佳做法改进的书面评论，请指教;例如声明ViewModel或设置StaticResource。我现在正在学习WPF和MVVM。

Answer 1

您没有将数据上下文设置为正确的!true == false

ViewModel

应该是：

DataContext = New ViewModel()

INotifyPropertyChanged不会导致此代码中的屏幕更新

1 个答案: