DataGrid 数据绑定/更新中的 WPF ComboBox 不起作用 [英] WPF ComboBox in DataGrid databinding/update not working

问题描述

如果我在 Visual Studio 2010 中设置一个新的 WPF 应用程序并添加以下代码+XAML，则会打开一个数据网格，其中包含组合框.现在的问题是通过组合框更改值不会传播到绑定数据模型.换句话说:永远不会设置名为 MyValue 的属性.现在花了我几个小时，我不知道为什么这不起作用.也有许多类似的主题和建议没有.

If I set up a new WPF application in Visual Studio 2010 and add the following code+XAML, a data grid opens with comboboxes inside. The problem now is that changeing a value through a combobox does not get propagated to the bound data model. In other words: the property named MyValue never gets set. It took me hours now and I have no clue why this doesn't work. Also many similar threads and suggestions didn't.

这里是 XAML.它只是一个包含 DataGrid 的简单窗口.DataGrid 有一个模板列，其中设置了 CellTemplate 和 CellEditingTemplate.两者都包含一个 ComboBox，其中填充了来自资源部分的列表.ComboBox.SelectedItem 绑定到 MyItem.MyValue:

Here the XAML. It is just a simple Window with a DataGrid contained. The DataGrid has a template column where CellTemplate and CellEditingTemplate are set. Both contain a ComboBox that is filled with the list from the resource section. The ComboBox.SelectedItem is bound to MyItem.MyValue:

<Window x:Class="DataGridComboBoxExample.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"    xmlns:local="clr-namespace:DataGridComboBoxExample">

    <Window.Resources>

        <local:MyItemList x:Key="ItemList"/>

        <DataTemplate x:Key="NotificationModeDataTemplate">
            <ComboBox
                ItemsSource="{StaticResource ItemList}"
                SelectedItem="{Binding Path=MyValue, Mode=OneWay}" />
        </DataTemplate>
        <DataTemplate x:Key="NotificationModeEditTemplate">
            <ComboBox
                ItemsSource="{StaticResource ItemList}"
                SelectedItem="{Binding Path=MyValue, Mode=TwoWay}" />
        </DataTemplate>

    </Window.Resources>

    <Grid>
        <DataGrid x:Name="myDataGrid" AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTemplateColumn
                    Header="Test" Width="100"
                    CellTemplate="{StaticResource NotificationModeDataTemplate}"
                    CellEditingTemplate="{StaticResource NotificationModeEditTemplate}" />
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

这里是代码.它包含仅设置 DataContext 的主 Window ctor.MyItem 是支持 INotifyPropertyChanged 的​​行数据模型.MyItemList 是绑定到 ComboBox.ItemsSource 的选项列表.

Here the code. It contains the main Window ctor which just sets up a DataContext. MyItem is the row's datamodel supporting INotifyPropertyChanged. MyItemList is the list of choices bound to ComboBox.ItemsSource.

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        myDataGrid.ItemsSource = new List<MyItem> 
        {
            new MyItem { MyValue = "i0" },
            new MyItem { MyValue = "i1" },
            new MyItem { MyValue = "i0" },
        };
    }
}

public class MyItem : INotifyPropertyChanged
{
    public string MyValue
    {
        get { return myValue; }
        set
        {
            myValue = value;
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("MyValue"));
            }
        }
    }
    private string myValue;

    public event PropertyChangedEventHandler PropertyChanged;
}

public class MyItemList : List<string>
{
    public MyItemList() { Add("i0"); Add("i1"); Add("i2"); }
}

推荐答案

我怀疑您需要使 SelectedItem 绑定更新 PropertyChanged 上的源才能使其工作.

I suspect you'll need to make the SelectedItem binding update the source on PropertyChanged for this to work.

SelectedItem="{Binding Path=MyValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"

SelectedItem="{Binding Path=MyValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"

我会在调试时让 CellTemplate 和 CellEditingTemplate 都引用您的编辑模板，以消除另一个不相关的模板，直到您将其整理好.

I'd make the CellTemplate and CellEditingTemplate both reference your edit template while debugging this, to eliminate the other, irrelevant, template until you get it sorted out.

这篇关于DataGrid 数据绑定/更新中的 WPF ComboBox 不起作用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！