如何根據bool值動態設置ComboBox綁定？

Question

我遇到過這種情況，我需要根據選擇哪個切換按鈕來動態設置組合框的Items源。

在應用程序中有兩個切換按鈕，高/普通。如果高位切換，我想將組合框的綁定設置爲higherGradePointKV，否則如果普通切換爲ordinaryGradePointKV。

到目前爲止，我設置了Bool屬性，用於更高/普通以及在視圖模型的構造函數中調用的。

我正在努力的部分是在此方法中設置來自代碼的綁定。

有誰知道我可以如何設置這個實現的其餘部分？

這就是布爾屬性和列表被定義並稱爲視圖模型：

namespace LC_Points.ViewModel 
{ 

    public class MainViewModel : ViewModelBase 
    { 

     /// <summary> 
     /// Initializes a new instance of the MainViewModel class. 
     /// </summary> 
     public MainViewModel() 
     { 
      //call methods to initilise list data 
      SetGradeComboBoxBinding(); 
      GetOrdinaryGradePairs(); 
      GetHigherGradePairs(); 
     } 

     public List<StringKeyValue> higherGradePointKV { get; set; } 
     public List<StringKeyValue> ordinaryGradePointKV { get; set; } 


     //ordinary toggle button bool 
     private bool _isOrdinaryToggled; 
     public bool IsOrdinaryToggled 
     { 
      get 
      { 
       return _isOrdinaryToggled; 
      } 
      set 
      { 
       _isOrdinaryToggled = value; 
       RaisePropertyChanged("IsOrdinaryToggled"); 
      } 
     } 

     //Higher toggle button bool property 
     private bool _isHigherToggled; 
     public bool IsHigherToggled 
     { 
      get 
      { 
       return _isHigherToggled; 
      } 
      set 
      { 
       _isHigherToggled = value; 
       RaisePropertyChanged("IsHigherToggled"); 
      } 
     } 


     //Sets the grade combo box binding based on button toggled. 
     public void SetGradeComboBoxBinding() 
     { 

      if(_isHigherToggled) 
      { 
       //set binding to higherGradePointKV 

      } 
      else if(_isOrdinaryToggled) 
      { 

       //set binding to higherGradePointKV 


      } 

     } 


     public class StringKeyValue 
     { 
      public string Key { get; set; } 
      public int Value { get; set; } 
     } 


     public void GetOrdinaryGradePairs() 
     { 

      List<StringKeyValue> ordianryGradePointKVTemp = new List<StringKeyValue>(); 


      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "A1", Value = 60 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "A2", Value = 50 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "B1", Value = 45 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "B2", Value = 40 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "B3", Value = 35 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "C1", Value = 30 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "C2", Value = 25 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "C3", Value = 20 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "D1", Value = 15 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "D2", Value = 10 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "D3", Value = 5 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "E,F,NG", Value = 0 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "Pass", Value = 30 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "Merit", Value = 50 }); 
      ordianryGradePointKVTemp.Add(new StringKeyValue { Key = "Distinction", Value = 70 }); 


      ordinaryGradePointKV = ordianryGradePointKVTemp; 

     } 


     public void GetHigherGradePairs() 
     { 

      List<StringKeyValue> higherGradePointKVTemp = new List<StringKeyValue>(); 


      higherGradePointKVTemp.Add(new StringKeyValue { Key = "A1", Value = 100 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "A2", Value = 90 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "B1", Value = 85 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "B2", Value = 80 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "B3", Value = 75 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "C1", Value = 70 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "C2", Value = 65 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "C3", Value = 60 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "D1", Value = 55 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "D2", Value = 50 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "D3", Value = 45 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "E,F,NG", Value = 0 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "Pass", Value = 30 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "Merit", Value = 50 }); 
      higherGradePointKVTemp.Add(new StringKeyValue { Key = "Distinction", Value = 70 }); 


      higherGradePointKV = higherGradePointKVTemp; 
     } 


    } 
} 

這是目前在那裏經由XAML指定只有一個物品來源視圖：

<Page x:Class="LC_Points.MainPage" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
     xmlns:local="using:LC_Points" 
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
     Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" 
     DataContext="{Binding Source={StaticResource Locator}}" 
     mc:Ignorable="d"> 



    <Grid> 
     <Grid.RowDefinitions> 
      <RowDefinition Height="40*" /> 
      <RowDefinition Height="20*" /> 
      <RowDefinition Height="30*" /> 
      <RowDefinition Height="30*" /> 
      <RowDefinition Height="20*" /> 
      <RowDefinition Height="20*" /> 
     </Grid.RowDefinitions> 
     <Grid.ColumnDefinitions> 
      <ColumnDefinition Width="4*" /> 
      <ColumnDefinition Width="3*" /> 
      <ColumnDefinition Width="2*" /> 
     </Grid.ColumnDefinitions> 

     <!-- TitlePanel contains the name of the application and page title --> 
     <StackPanel x:Name="TitlePanel" 
        Grid.Row="0" 
        Margin="12,17,0,28"> 
      <TextBlock Style="{StaticResource SubheaderTextBlockStyle}" Text="LC POINTS" /> 
      <TextBlock Margin="9,-7,0,0" 
         Foreground="DarkGreen" 
         Style="{StaticResource HeaderTextBlockStyle}" 
         Text="Home" /> 
     </StackPanel> 

     <ComboBox x:Name="gradeCmbBx" 
        Grid.Row="1" 
        Grid.Column="0" 
        Grid.ColumnSpan="2" 
        Width="60" 
        HorizontalAlignment="Right" 
        DisplayMemberPath="Key" 
        ItemsSource="{Binding ordinaryGradePointKV}" /> 


     <ToggleButton x:Name="higherTglBtn" 
         Grid.Row="3" 
         HorizontalAlignment="Left" 
         Content="Higher" 
         IsChecked="{Binding IsHigherToggled, 
              Mode=TwoWay}" /> 
     <ToggleButton x:Name="ordinaryTglBtn" 
         Grid.Row="3" 
         Grid.ColumnSpan="2" 
         HorizontalAlignment="Center" 
         Content="Ordinary" 
         IsChecked="{Binding IsOrdinaryToggled, 
              Mode=TwoWay}" /> 

    </Grid> 


</Page> 

Answer 1

在組合框的自定義樣式上使用Triggers屬性來更改源。

<ComboBox 
    Grid.Row="1" 
    Grid.Column="0" 
    Grid.ColumnSpan="2" 
    Width="60" 
    HorizontalAlignment="Right" 
    DisplayMemberPath="Key"> 
    <ComboBox.Style> 
     <Style> 
      <Setter Property="ComboBox.ItemsSource" Value="{Binding ordinaryGradePointKV}"></Setter> 
      <Style.Triggers> 
       <DataTrigger Binding="{Binding IsHigherToggled}" Value="True"> 
        <Setter Property="ComboBox.ItemsSource" 
         Value="{Binding higherGradePointKV}" /> 
       </DataTrigger> 
      </Style.Triggers> 
     </Style> 
    </ComboBox.Style> 
</ComboBox>