在MVVM中使用WPF DataGridComboBoxColumn - 在ViewModel中綁定到屬性

Question

我使用了優秀的MVVM Light Toolkit。我的視圖模型公開：

public const string CourtCodesTypeCourtPropertyName = "CourtCodesTypeCourt"; 
private List<CourtType> _courtCodesTypes = new List<CourtType>(); 
public List<CourtType> CourtCodesTypeCourt 
{ 
    get 
    { 
     return _courtCodesTypes; 
    } 

    set 
    { 
     if (_courtCodesTypes == value) 
     { 
      return; 
     } 

     var oldValue = _courtCodesTypes; 
     _courtCodesTypes = value; 

     // Update bindings and broadcast change using GalaSoft.MvvmLight.Messenging 
     RaisePropertyChanged(CourtCodesTypeCourtPropertyName, oldValue, value, true); 
    } 
} 

public const string CourtCodesPropertyName = "CourtCodes"; 
private List<Court> _courtCodes = null; 
public List<Court> CourtCodes 
{ 
    get 
    { 
     return _courtCodes; 
    } 

    set 
    { 
     if (_courtCodes == value) 
     { 
      return; 
     } 

     var oldValue = _courtCodes; 
     _courtCodes = value; 

     // Update bindings and broadcast change using GalaSoft.Utility.Messenging 
     RaisePropertyChanged(CourtCodesPropertyName, oldValue, value, true); 
    } 
} 

視圖有一個DataGrid：

<DataGrid 
     ItemsSource="{Binding CourtCodes, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
     AutoGenerateColumns="False" 
     AlternatingRowBackground="{DynamicResource OffsetBrown}" 
     AlternationCount="1" Margin="45,0"> 
    <DataGrid.Columns> 
    <DataGridTextColumn Binding="{Binding Abbreviation, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
     Header="Abbreviation" 
     Width="25*" /> 
    <DataGridTextColumn Binding="{Binding FullName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
     Header="Court" 
     Width="75*" /> 
    <DataGridComboBoxColumn Header="CourtType" 
     ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, Path=DataContext.CourtCodesTypeCourt} TextBinding="{Binding CourtTypeDescription}""/> 
    </DataGrid.Columns> 
    </DataGrid> 

數據網格有一個ItemsSource時，你可以看到CourtCodes的。我希望CourtType列是CourtCodesTypeCourt中包含的所有列舉的CourtType的下拉列表。對於我的生活，我似乎無法用任何東西填充DataGridComboBoxColumn。當前失敗的嘗試正在尋找使用RelativeSource ...我做錯了什麼？

除了不能工作，這兩個錯誤，我看到的是：

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Window', AncestorLevel='1''. BindingExpression:Path=DataContext.CourtCodesTypeCourt; DataItem=null; target element is 'DataGridComboBoxColumn' (HashCode=38771709); target property is 'ItemsSource' (type 'IEnumerable')

和

System.Windows.Data Error: 40 : BindingExpression path error: 'CourtCodesTypeCourt' property not found on 'object' ''Court' (HashCode=38141773)'. BindingExpression:Path=CourtCodesTypeCourt.CourtTypeDescription; DataItem='Court' (HashCode=38141773); target element is 'ComboBox' (Name=''); target property is 'Text' (type 'String')

Answer 1

DataGrid列定義不參加你所期望的方式邏輯樹。這是荒謬的，但我最後一次檢查，你必須做這樣的事情：

<DataGridComboBoxColumn Header="CourtType" SelectedItemBinding="{Binding Type}"> 
    <DataGridComboBoxColumn.ElementStyle> 
     <Style TargetType="ComboBox"> 
      <Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, Path=DataContext.CourtCodesTypeCourt}"/> 
      <Setter Property="IsReadOnly" Value="True"/> 
     </Style> 
    </DataGridComboBoxColumn.ElementStyle> 
    <DataGridComboBoxColumn.EditingElementStyle> 
     <Style TargetType="ComboBox"> 
      <Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, Path=DataContext.CourtCodesTypeCourt}"/> 
     </Style> 
    </DataGridComboBoxColumn.EditingElementStyle> 
</DataGridComboBoxColumn> 

你會發現我也改變了你的TextBinding到SelectedItemBinding。我不確定你是否真的想要TextBinding，但如果你只是想讓用戶在列表中進行選擇，那麼SelectedItemBinding可能就是你想要的。

另外，您的虛擬機並不完全遵循最佳實踐。您使用的是List<T>而不是ObservableCollection<T>，並且您將其公開爲List<T>而不是簡單的東西，例如ICollection<T>。

Answer 2

在這裏，我已經找到答案http://cinch.codeplex.com/discussions/239522

對於DataGridComboBoxColumn你要創建的ItemsSource的StaticRecource，如：

<CollectionViewSource Source="{Binding Element=theView, Path=DataContext.ViewModelCollection1}" x:Key="ViewModelCollection1" /> 

，並與下面綁定到DataGridComboBoxColumn：

ItemsSource="{Binding Source={StaticResource ViewModelCollection1}}" 

這是因爲DataGridColumns不是可視化樹的一部分。

如果你想在DataGrid中的項目的集合捆綁，你必須在兩種風格設置的ItemsSource：

<DataGridComboBoxColumn.ElementStyle> 
    <Style TargetType="ComboBox"> 
     <Setter Property="ItemsSource" Value="{Binding Path=ModelCollection1}" /> 
    </Style> </DataGridComboBoxColumn.ElementStyle> <DataGridComboBoxColumn.EditingElementStyle> 
    <Style TargetType="ComboBox"> 
     <Setter Property="ItemsSource" Value="{Binding Path=ModelCollection1}" /> 
    </Style> </DataGridComboBoxColumn.EditingElementStyle> 

Answer 3

看看這個精彩教程/例如： https://code.msdn.microsoft.com/windowsdesktop/Best-ComboBox-Tutorial-5cc27f82