Question

我有ListView，其中每个元素主要由2列DataGrid组成。

<ListView Name="SelectedWhereItemListView" 
          ItemsSource="{Binding AddedWhereItems}"
          VerticalContentAlignment="Top">
   <ListView.ItemsPanel>
      <ItemsPanelTemplate>
         <StackPanel Orientation="Horizontal" />
      </ItemsPanelTemplate>
   </ListView.ItemsPanel>
   <ListView.ItemTemplate>
      <DataTemplate>
         <StackPanel Orientation="Vertical">
            <TextBlock Text="{Binding TableName}" />
            <TextBlock Text="{Binding ColumnName}" />
            <DataGrid SelectionMode="Single" AutoGenerateColumns="False" ItemsSource="{Binding WhereFieldCondition}">
               <DataGrid.Columns>
                  <DataGridComboBoxColumn Width="Auto" Header="{lex:Loc Key=Operator}" SelectedValueBinding="{Binding Operator}">
                     <DataGridComboBoxColumn.ElementStyle>
                        <Style TargetType="{x:Type ComboBox}">
                           <Setter Property="ItemsSource" Value="{Binding Path=DataContext.WhereFieldConditions[DataType], RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
                        </Style>
                     </DataGridComboBoxColumn.ElementStyle>
                     <DataGridComboBoxColumn.EditingElementStyle>
                        <Style TargetType="{x:Type ComboBox}">
                           <Setter Property="ItemsSource" Value="{Binding Path=DataContext.WhereFieldConditions[DataType], RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
                        </Style>
                     </DataGridComboBoxColumn.EditingElementStyle>
                  </DataGridComboBoxColumn>
                  <DataGridTextColumn Width="Auto" Header="{lex:Loc Key=Value}" Binding="{Binding Value}" />
               </DataGrid.Columns>
            </DataGrid>
         </StackPanel>
      </DataTemplate>
   </ListView.ItemTemplate>
</ListView>

我使用DataGrid为ListView元素指定1..n运算符/值对。

在当前图形结果下方，只是为了有一个更具体的想法

ListView的每个元素都是最终生成的查询的where子句。每个块都有一个数据类型（int，varchar等）。基于ListView元素数据类型，我想填充数据网格的DataGridComboBoxColumn运算符。

我在ViewModel中创建了这个属性

public Dictionary<string, ObservableCollection<string>> WhereFieldConditions
{
    get
    {
        if (_whereFieldconditions == null)
        {
            _whereFieldconditions = new Dictionary<string, ObservableCollection<string>>();
            _whereFieldconditions.Add("int", new ObservableCollection<string>(new string[] { "<", ">", "=", "!=" }.ToList<string>()));
            _whereFieldconditions.Add("decimal", new ObservableCollection<string>(new string[] { "<", ">", "=", "!=" }.ToList<string>()));
            _whereFieldconditions.Add("nvarchar", new ObservableCollection<string>(new string[] { "=", "like" }.ToList<string>()));
            _whereFieldconditions.Add("varchar", new ObservableCollection<string>(new string[] { "=", "like" }.ToList<string>()));
            _whereFieldconditions.Add("char", new ObservableCollection<string>(new string[] { "=", "like" }.ToList<string>()));
            _whereFieldconditions.Add("datetime", new ObservableCollection<string>(new string[] { "<", ">", "=" }.ToList<string>()));

        }
        return _whereFieldconditions;
    }
}

不幸的是（对我:)）我获得了以下异常

System.Windows.Data Error: 17 : Cannot get 'Item[]' value (type 'ObservableCollection`1') from 'WhereFieldConditions' (type 'Dictionary`2'). BindingExpression:Path=DataContext.WhereFieldConditions[.DataType]; DataItem='StockageQueryEditorView' (Name=''); target element is 'TextBlockComboBox' (Name=''); target property is 'ItemsSource' (type 'IEnumerable') TargetInvocationException:'System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
   at System.ThrowHelper.ThrowKeyNotFoundException()
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at MS.Internal.Data.PropertyPathWorker.GetValue(Object item, Int32 level)
   at MS.Internal.Data.PropertyPathWorker.RawValue(Int32 k)'

但我目前无法使用ListView项中包含的对象的DataType映射DataGridComboBoxColumn。我不知道如何修改这个绑定，以使其正常工作，如果这是正确的方法，也不要老实说：

Binding Path=DataContext.WhereFieldConditions[DataType], RelativeSource={RelativeSource AncestorType={x:Type Window}

Answer 1

但我目前无法使用ListView项中包含的对象的DataType映射DataGridComboBoxColumn

您无法在XAML中执行此操作。 XAML是标记语言，无法使用ItemsSource解析ListView [DataType]中基础对象的类型。这不受支持。

您可以使用multi value converter获取Dictionary<string, ObservableCollection<string>>和数据对象，并根据对象的类型返回正确的ObservableCollection<string>：

<Style TargetType="{x:Type ComboBox}">
    <Setter Property="ItemsSource">
        <Setter.Value>
            <MultiBinding Converter="{StaticResource conv}">
                <Binding Path="DataContext.WhereFieldConditions" RelativeSource="{RelativeSource AncestorType={x:Type Window}}" />
                <Binding Path="DataContext" RelativeSource="{RelativeSource AncestorType=ListViewItem}" />
            </MultiBinding>
        </Setter.Value>
    </Setter>
</Style>

将DataGridComboBoxColumn绑定到Dictionary

1 个答案: