Я воспроизвел вашу проблему, и я достиг своей задачу.
Это первоначальный вид.
Затем после выбора Кегалла,
Я думаю, что это то, что вам нужно.
Определить view model для ComboBoxItem. (В моем случае я создал класс под названием MyComboBoxItem и включаю в себя свойство, а именно HasVisited, Address, City, TextBoxValue)
В вашей основной модели представления, определить property связать ComboBox ItemsSource (я определил свойство ComboBoxItems) и другое свойство связывать SelectedItem из ComboBox (я определил свойство, называемое SelectedComboBoxItem).
В способе изменения выбора вставьте свою логику для установки texbox.
Вот мой XAML
<Window x:Class="ComboboxSelectedItemChange.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:vm="clr-namespace:ComboboxSelectedItemChange.ViewModels"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.DataContext>
<vm:MainViewModel />
</Grid.DataContext>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="40" />
<RowDefinition Height="30" />
</Grid.RowDefinitions>
<Label Grid.Column="0" Grid.Row="0" Content="Combo box test" />
<ComboBox Grid.Column="1" Grid.Row="1"
ItemsSource="{Binding ComboBoxItems}"
SelectedItem="{Binding SelectedComboBoxItem}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox IsChecked="{Binding HasVisited}" Width="30" />
<TextBlock Text="{Binding TextBoxValue}" Width="100" />
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<i:InvokeCommandAction Command="{Binding ChangeSelectionCommand}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
</Grid>
И это мой Main View model, который связывается с выше зрения
public class MainViewModel : ViewModelBase
{
#region Declarations
private ObservableCollection<MyComboBoxItemViewModel> comboBoxItems;
private MyComboBoxItemViewModel selectedComboBoxItem;
private ICommand changeSelectionCommand;
#endregion
#region Properties
/// <summary>
/// Gets or sets the combo box items.
/// </summary>
/// <value>The combo box items.</value>
public ObservableCollection<MyComboBoxItemViewModel> ComboBoxItems
{
get
{
return comboBoxItems;
}
set
{
comboBoxItems = value;
NotifyPropertyChanged("ComboBoxItems");
}
}
/// <summary>
/// Gets or sets the selected combo box item.
/// </summary>
/// <value>The selected combo box item.</value>
public MyComboBoxItemViewModel SelectedComboBoxItem
{
get
{
return selectedComboBoxItem;
}
set
{
selectedComboBoxItem = value;
NotifyPropertyChanged("SelectedComboBoxItem");
}
}
#endregion
#region Commands
/// <summary>
/// Gets the change selection command.
/// </summary>
/// <value>The change selection command.</value>
public ICommand ChangeSelectionCommand
{
get
{
if (changeSelectionCommand == null)
{
changeSelectionCommand = new RelayCommand(param => this.ChangeSelection(),
null);
}
return changeSelectionCommand;
}
}
#endregion
#region Constructors
/// <summary>
/// Initializes a new instance of the <see cref="MainViewModel"/> class.
/// </summary>
public MainViewModel()
{
//Add some dummy data
this.ComboBoxItems = new ObservableCollection<MyComboBoxItemViewModel>();
MyComboBoxItemViewModel item1 = new MyComboBoxItemViewModel();
item1.HasVisited = false;
item1.Address = "123, Matara";
item1.City = "Matara";
item1.TextBoxValue = item1.City;
this.ComboBoxItems.Add(item1);
MyComboBoxItemViewModel item2 = new MyComboBoxItemViewModel();
item2.HasVisited = false;
item2.Address = "125, Colombo";
item2.City = "Colombo";
item2.TextBoxValue = item2.City;
this.ComboBoxItems.Add(item2);
MyComboBoxItemViewModel item3 = new MyComboBoxItemViewModel();
item3.HasVisited = false;
item3.Address = "465, Kegalle";
item3.City = "Kegalle";
item3.TextBoxValue = item3.City;
this.ComboBoxItems.Add(item3);
this.SelectedComboBoxItem = item2;
this.ComboBoxItems.Where(item => item == this.SelectedComboBoxItem).First().TextBoxValue = this.SelectedComboBoxItem.Address;
}
#endregion
#region Private Methods
/// <summary>
/// Changes the selection.
/// </summary>
private void ChangeSelection()
{
foreach (var comboBoxitem in this.ComboBoxItems)
{
this.ComboBoxItems.Where(item => item == comboBoxitem).First().TextBoxValue = comboBoxitem.City;
}
this.ComboBoxItems.Where(item => item == this.SelectedComboBoxItem).First().TextBoxValue = this.SelectedComboBoxItem.Address;
this.ComboBoxItems.Where(item => item == this.SelectedComboBoxItem).First().HasVisited = true;
}
#endregion
}
И это MyComboBoxItemViewModel
public class MyComboBoxItemViewModel : ViewModelBase
{
#region Declarations
private bool hasVisited;
private string address;
private string city;
private string textBoxValue;
#endregion
#region Properties
/// <summary>
/// Gets or sets a value indicating whether this instance has visited.
/// </summary>
/// <value>
/// <c>true</c> if this instance has visited; otherwise, <c>false</c>.
/// </value>
public bool HasVisited
{
get
{
return hasVisited;
}
set
{
hasVisited = value;
NotifyPropertyChanged("HasVisited");
}
}
/// <summary>
/// Gets or sets the address.
/// </summary>
/// <value>The address.</value>
public string Address
{
get
{
return address;
}
set
{
address = value;
NotifyPropertyChanged("Address");
}
}
/// <summary>
/// Gets or sets the city.
/// </summary>
/// <value>The city.</value>
public string City
{
get
{
return city;
}
set
{
city = value;
NotifyPropertyChanged("City");
}
}
/// <summary>
/// Gets or sets the text box value.
/// </summary>
/// <value>The text box value.</value>
public string TextBoxValue
{
get
{
return textBoxValue;
}
set
{
textBoxValue = value;
NotifyPropertyChanged("TextBoxValue");
}
}
#endregion
}