在 WPF DataGrid 中绑定 ComboBoxColumn 的 ItemsSource [英] Binding ItemsSource of a ComboBoxColumn in WPF DataGrid

问题描述

我有两个简单的 Model 类和一个 ViewModel...

I have two simple Model classes and a ViewModel...

public class GridItem
{
    public string Name { get; set; }
    public int CompanyID { get; set; }
}

public class CompanyItem
{
    public int ID { get; set; }
    public string Name { get; set; }
}

public class ViewModel
{
    public ViewModel()
    {
        GridItems = new ObservableCollection<GridItem>() {
            new GridItem() { Name = "Jim", CompanyID = 1 } };

        CompanyItems = new ObservableCollection<CompanyItem>() {
            new CompanyItem() { ID = 1, Name = "Company 1" },
            new CompanyItem() { ID = 2, Name = "Company 2" } };
    }

    public ObservableCollection<GridItem> GridItems { get; set; }
    public ObservableCollection<CompanyItem> CompanyItems { get; set; }
}

...和一个简单的窗口:

...and a simple Window:

<Window x:Class="DataGridComboBoxColumnApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <DataGrid AutoGenerateColumns="False" ItemsSource="{Binding GridItems}" >
            <DataGrid.Columns>
                <DataGridTextColumn Binding="{Binding Name}" />
                <DataGridComboBoxColumn ItemsSource="{Binding CompanyItems}"
                                    DisplayMemberPath="Name"
                                    SelectedValuePath="ID"
                                    SelectedValueBinding="{Binding CompanyID}" />
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

ViewModel 设置为 App.xaml.cs 中 MainWindow 的 DataContext:

The ViewModel is set to the MainWindow's DataContext in App.xaml.cs:

public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);

        MainWindow window = new MainWindow();
        ViewModel viewModel = new ViewModel();

        window.DataContext = viewModel;
        window.Show();
    }
}

如您所见，我将 DataGrid 的 ItemsSource 设置为 ViewModel 的 GridItems 集合.这部分工作，显示名称为Jim"的单个网格线.

As you can see I set the ItemsSource of the DataGrid to the GridItems collection of the ViewModel. This part works, the single Grid line with Name "Jim" is displayed.

我还想将每行 ComboBox 的 ItemsSource 设置为 ViewModel 的 CompanyItems 集合.这部分不起作用:组合框保持为空，在调试器输出窗口中我看到一条错误消息:

I also want to set the ItemsSource of the ComboBox in every row to the CompanyItems collection of the ViewModel. This part does not work: The ComboBox remains empty and in the Debugger Output Window I see an error message:

System.Windows.Data 错误:2:不能找到管理 FrameworkElement 或目标的 FrameworkContentElement元素.BindingExpression:Path=CompanyItems;数据项=空；目标元素是'DataGridComboBoxColumn'(哈希码=28633162)；目标财产是ItemsSource"(类型IEnumerable")

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=CompanyItems; DataItem=null; target element is 'DataGridComboBoxColumn' (HashCode=28633162); target property is 'ItemsSource' (type 'IEnumerable')

我相信 WPF 希望 CompanyItems 成为 GridItem 的属性，但事实并非如此，这就是绑定失败的原因.

I believe that WPF expects CompanyItems to be a property of GridItem which is not the case, and that's the reason why the binding fails.

我已经尝试使用 RelativeSource 和 AncestorType 像这样:

I've already tried to work with a RelativeSource and AncestorType like so:

<DataGridComboBoxColumn ItemsSource="{Binding CompanyItems, 
    RelativeSource={RelativeSource Mode=FindAncestor,
                                   AncestorType={x:Type Window}}}"
                        DisplayMemberPath="Name"
                        SelectedValuePath="ID"
                        SelectedValueBinding="{Binding CompanyID}" />

但这在调试器输出中给了我另一个错误:

But that gives me another error in the debugger output:

System.Windows.Data 错误:4:不能查找绑定参考源'RelativeSource FindAncestor,AncestorType='System.Windows.Window',AncestorLevel='1''.BindingExpression:Path=CompanyItems;数据项=空；目标元素是'DataGridComboBoxColumn'(哈希码=1150788)；目标属性是'ItemsSource'(类型 'IEnumerable')

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Window', AncestorLevel='1''. BindingExpression:Path=CompanyItems; DataItem=null; target element is 'DataGridComboBoxColumn' (HashCode=1150788); target property is 'ItemsSource' (type 'IEnumerable')

问题:如何将 DataGridComboBoxColumn 的 ItemsSource 绑定到 ViewModel 的 CompanyItems 集合?有可能吗?

提前感谢您的帮助！

推荐答案

请检查以下 DataGridComboBoxColumn xaml 是否适合您:

Pls, check if DataGridComboBoxColumn xaml below would work for you:

<DataGridComboBoxColumn 
    SelectedValueBinding="{Binding CompanyID}" 
    DisplayMemberPath="Name" 
    SelectedValuePath="ID">

    <DataGridComboBoxColumn.ElementStyle>
        <Style TargetType="{x:Type ComboBox}">
            <Setter Property="ItemsSource" Value="{Binding Path=DataContext.CompanyItems, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
        </Style>
    </DataGridComboBoxColumn.ElementStyle>
    <DataGridComboBoxColumn.EditingElementStyle>
        <Style TargetType="{x:Type ComboBox}">
            <Setter Property="ItemsSource" Value="{Binding Path=DataContext.CompanyItems, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
        </Style>
    </DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>

您可以在这里找到解决您所面临问题的另一种解决方案:在 WPF DataGrid 中使用组合框

Here you can find another solution for the problem you're facing: Using combo boxes with the WPF DataGrid

这篇关于在 WPF DataGrid 中绑定 ComboBoxColumn 的 ItemsSource的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！