WPF：根據另一個下拉列表上的值啓用下拉列表

Question

我的視圖中有兩個組合框。

我想要的是，當我在ComboBox1上選擇值1時，ComboBox2變爲啓用狀態。但是，當我在ComboBox1中選擇任何其他不是1的值時，ComboBox2保持禁用狀態。

Answer 1

您的XAML：

<ComboBox x:Name="cb1" Margin="10,0" IsReadOnly="True" IsEditable="True" Text="Please select" HorizontalAlignment="Center" > 
    <ComboBoxItem x:Name="cbi11" Content="Option1" HorizontalAlignment="Left" Width="198" Selected="cbi11_Selected" /> 
    <ComboBoxItem x:Name="cbi12" Content="Option2" HorizontalAlignment="Left" Width="198" Selected="cbi12_Selected"/> 
    <ComboBoxItem x:Name="cbi13" Content="Option3" HorizontalAlignment="Left" Width="198" Selected="cbi13_Selected"/> 
</ComboBox> 

<ComboBox x:Name="cb2" Margin="10,0" IsReadOnly="True" IsEditable="True" Text="Please select" HorizontalAlignment="Center" > 
    <ComboBoxItem x:Name="cbi21" Content="Option1" HorizontalAlignment="Left" Width="198" Selected="cbi21_Selected" /> 
    <ComboBoxItem x:Name="cbi22" Content="Option2" HorizontalAlignment="Left" Width="198" Selected="cbi22_Selected"/> 
    <ComboBoxItem x:Name="cbi23" Content="Option3" HorizontalAlignment="Left" Width="198" Selected="cbi23_Selected"/> 
</ComboBox> 

而且背後的代碼：

private void cbi11_Selected(object sender, RoutedEventArgs e) 
    { 
     cb2.IsEnabled = true; 
    } 
private void cbi12_Selected(object sender, RoutedEventArgs e) 
    { 
     cb2.IsEnabled = false; 
    } 
private void cbi13_Selected(object sender, RoutedEventArgs e) 
    { 
     cb2.IsEnabled = false; 
    } 

Answer 2

如果你正確地這樣做，那麼你問錯了問題爲您的視圖模型將完成大部分的工作，爲你

假設你有一個這樣的視圖模型（使用Prism）

public class VM:BindableBase 
{ 
    public ICollectionView Combo1Options {get,set} 
    public ICollectionView Combo2Options {get,set} 

    private object _Combo1Value; 
    private object _Combo2Value; 

    public object Combo1Value 
    { 
     get { return _Combo1Value; } 
     set 
     { 
      if(SetProperty(ref _Combo1Value, value)) 
      { 
       Combo2Options .Refresh(); 
       PropertyChanged(nameof(Combo2Enabled));      
      } 
     } 
    } 

    public object Combo2Value 
    { 
     get { return _Combo2Value; } 
     set { SetProperty(ref _Combo2Value, value); } 
    } 
    public bool Combo2Enabled => Combo1Value != null;//or what ever logic defines if combo2 is required 

} 

那麼你就只綁定到視圖模型

<ComboBox ItemSource={Binding Combo1Options }, SelectedItem={Binding Combo1Value }/> 
<ComboBox ItemSource={Binding Combo2Options }, SelectedItem={Binding Combo2Value } IsEnabled={Binding Combo2Enabled}/> 

使用的CollectionView的你獲得過濾的組合框項目的能力，所以我會推薦它