无法在 MainWindow.xaml.cs 中获取选定的组合框项

我想在MainWindow.xaml.cs中访问ComboBox项目(在另一个类中定义(，但我不能。

我是 C# 和 WPF 的新手。此代码的目的是获取选定的组合框项作为搜索键。我已经从互联网上的许多示例代码中复制了，现在我完全迷失了。我什至不知道哪个部分是错误的。所以，让我展示整个代码(对不起(：

MainWindow.xaml：

<Window x:Class="XY.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:XY"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="454.4">
<Grid>
<DataGrid ItemsSource="{Binding channels}"
SelectedItem="{Binding SelectedRow, Mode=TwoWay}"
Margin="0,0,0,-0.2">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding name}"
Header="Channel" Width="Auto"/>
<DataGridTemplateColumn Width="100" Header="Point Setting">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox x:Name="piontsComboBox"
ItemsSource="{Binding DataContext.points,
RelativeSource={RelativeSource AncestorType={x:Type Window}}}"
SelectionChanged="PrintText"
DisplayMemberPath="name" 
SelectedValuePath="name"
Margin="5"
SelectedItem="{Binding DataContext.SelectedPoint,
RelativeSource={RelativeSource AncestorType={x:Type Window}},
Mode=TwoWay}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
<TextBox x:Name="tb" Width="140" Height="30" Margin="10,250,200,30"></TextBox>
<Button x:Name="Browse_Button" Content="Browse" Margin="169,255,129.6,0"
Width="75" Click="Browse_Button_Click" Height="30" VerticalAlignment="Top"/>
</Grid>

MainWindow.xaml.cs：

using System;
using System.Windows;
using System.Windows.Controls;
namespace XY
{
public partial class MainWindow : Window
{
public GridModel gridModel { get; set; }
public MainWindow()
{
InitializeComponent();
gridModel = new GridModel();
this.DataContext = gridModel;
}
private void Browse_Button_Click(object sender, RoutedEventArgs e)
{
WakeupClass clsWakeup = new WakeupClass();
clsWakeup.BrowseFile += new EventHandler(gridModel.ExcelFileOpen);
clsWakeup.Start();
}
void PrintText(object sender, SelectionChangedEventArgs args)
{
//var item = pointsComboBox SelectedItem as Point;
//if(item != null)
//{
//    tb.Text = "You selected " + item.name + ".";
//}
MessageBox.Show("I'd like to show the item.name in the TextBox.");
}
}
public class WakeupClass
{
public event EventHandler BrowseFile;
public void Start()
{
BrowseFile(this, EventArgs.Empty);
}
}
}

点.cs：

namespace XY
{
public class Point : ViewModelBase
{
private string _name;
public string name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("name");
}
}
private int _code;
public int code
{
get { return _code; }
set
{
_code = value;
OnPropertyChanged("code");
}
}
}
}

记录.cs：

namespace XY
{
public class Record : ViewModelBase
{
private string _name;
public string name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("name");
}
}
private int _PointCode;
public int PointCode
{
get { return _PointCode; }
set
{
_PointCode = value;
OnPropertyChanged("PointCode");
}
}
private Record _selectedRow;
public Record selectedRow
{
get { return _selectedRow; }
set
{
_selectedRow = value;
OnPropertyChanged("SelectedRow");
}
}
private Point _selectedPoint;
public Point SelectedPoint
{
get { return _selectedPoint; }
set
{
_selectedPoint = value;
_selectedRow.PointCode = _selectedPoint.code;
OnPropertyChanged("SelectedRow");
}
}
}
}

ViewModelBase.cs：

using System.ComponentModel;
namespace XY
{
public class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
}
}

网格模型.cs：

using System.Collections.ObjectModel;
using System.Windows;
namespace XY
{
public class GridModel : ViewModelBase
{
public ObservableCollection<Record> channels { get; set; }
public ObservableCollection<Point> points { get; set; }
public GridModel()
{
channels = new ObservableCollection<Record>() {
new Record {name = "High"},
new Record {name = "Middle"},
new Record {name = "Low"}
};
}
internal void ExcelFileOpen(object sender, System.EventArgs e)
{
points = new ObservableCollection<Point> { new Point { } };
points.Add(new Point { name = "point1", code = 1 });
points.Add(new Point { name = "point2", code = 2 });
points.Add(new Point { name = "point3", code = 3 });
MessageBox.Show("Assume that Excel data are loaded here.");
}
}
}

该过程是这样的：

单击"浏览"按钮以加载数据。
单击第一列"频道"对列表进行排序(这是一个错误，但如果不这样做，"点设置"项将不会显示(。
单击"点设置"组合框以选择项目(点 1、点 2、...等(。

此代码应在文本框中显示选定的项名称。

如果所有内容都在 MainWindow.xaml.cs 中，则可以访问 ComboBox 项。自从我将代码分成不同的类以来，它一直不起作用。请帮助我。任何建议都会有所帮助。

您的绑定确实有效。您可以使用sender对象来实现所需的目标。

void PrintText(object sender, SelectionChangedEventArgs args)
{
var comboBox = sender as ComboBox;
var selectedPoint = comboBox.SelectedItem as Point;
tb.Text = selectedPoint.name;
}

问题是 DataGridColumn 不是 WPF 逻辑树的一部分，因此您的相对源绑定将不起作用。使绑定正常工作的唯一方法是一种 kluge(根据我的经验，WPF 非常常见(。创建一个逻辑树中的虚拟元素，然后引用该元素。

所以

<FrameworkElement x:Name="dummyElement" Visibility="Collapsed"/>
<DataGrid ItemsSource="{Binding channels}"
SelectedItem="{Binding SelectedRow, Mode=TwoWay}"
Margin="0,0,0,-0.2">

那么你的绑定将如下所示

<ComboBox x:Name="piontsComboBox"
ItemsSource="{Binding DataContext.points,
Source={x:Reference dummyElement}}"
SelectionChanged="PrintText"
DisplayMemberPath="name" 
SelectedValuePath="name"
Margin="5"
SelectedItem="{Binding DataContext.SelectedPoint,
Source={x:Reference dummyElement},
Mode=TwoWay}"/>

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