在MVVM中使用WPF DataGridComboBoxColumn - 在ViewModel中绑定到属性

Question

我使用了优秀的MVVM Light Toolkit。我的视图模型公开：

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); 
    } 
} 

视图有一个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> 

数据网格有一个ItemsSource时，你可以看到CourtCodes的。我希望CourtType列是CourtCodesTypeCourt中包含的所有列举的CourtType的下拉列表。对于我的生活，我似乎无法用任何东西填充DataGridComboBoxColumn。当前失败的尝试正在寻找使用RelativeSource ...我做错了什么？

除了不能工作，这两个错误，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列定义不参加你所期望的方式逻辑树。这是荒谬的，但我最后一次检查，你必须做这样的事情：

<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> 

你会发现我也改变了你的TextBinding到SelectedItemBinding。我不确定你是否真的想要TextBinding，但如果你只是想让用户在列表中进行选择，那么SelectedItemBinding可能就是你想要的。

另外，您的虚拟机并不完全遵循最佳实践。您使用的是List<T>而不是ObservableCollection<T>，并且您将其公开为List<T>而不是简单的东西，例如ICollection<T>。

Answer 2

在这里，我已经找到答案http://cinch.codeplex.com/discussions/239522

对于DataGridComboBoxColumn你要创建的ItemsSource的StaticRecource，如：

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

，并与下面绑定到DataGridComboBoxColumn：

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

这是因为DataGridColumns不是可视化树的一部分。

如果你想在DataGrid中的项目的集合捆绑，你必须在两种风格设置的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

看看这个精彩教程/例如： https://code.msdn.microsoft.com/windowsdesktop/Best-ComboBox-Tutorial-5cc27f82