Develop Reference

WPF - How to trigger an event for each element(button) in a ListBox?

I'd like to trigger event for the elemens which is button in a listbox, the view is as below. It is a listbox with 32 buttons.The purpose is to toggle the button between 0-1 and trigger event for each element.
There are two solutions I am thinking about. The solution one is to set command for each button, it works but the problem is I can't catch a selectedItem or a selectedIndex successfully so that even thougn I know the button is toggled, but I don't know the item index.
<ListBox x:Name="lbDirection"
Grid.Row="1"
Grid.Column="1"
SelectionMode="Extended"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
ScrollViewer.VerticalScrollBarVisibility="Disabled"
Margin="30,26,44,83"
Style="{StaticResource ListBoxHorz}"
ItemContainerStyle="{StaticResource ItemNoBorder}"
SelectedItem="{Binding SelectedLineItem}"
ItemsSource="{Binding ButtonList}"
IsSynchronizedWithCurrentItem="True">
<ListBox.ItemTemplate>
<DataTemplate>
<Button Style="{StaticResource ChangeButton}"
Command="{Binding DataContext.ToggleDirectionCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType= ListBox}}">
<Button.Content>
<TextBlock Text="{Binding BtnText}"
TextDecorations="Underline" />
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
ViewModel:
public class DigitalIOViewModel : BindableBase
{
public ICommand ToggleDirectionCommand { get; set; }
public ICommand ToggleStateCommand { get; set; }
private ObservableCollection<LineButtons> btnlist;
private LineButtons _selectedLineItem;
public LineButtons SelectedLineItem
{
get { return _selectedLineItem; }
set {
_selectedLineItem=value;
OnPropertyChanged("SelectedLineItem");
}
}
public DigitalIOViewModel()
{
btnlist = new ObservableCollection<LineButtons>();
CreateButtonList();
ToggleDirectionCommand = new RelayCommand(ToggleDirectionAction);
}
private void ToggleDirectionAction()
{
LineButtons selectedLineItem = SelectedLineItem;
int lineIndex=(SelectedLineItem!= null && ButtonList!=null)? ButtonList.IndexOf(SelectedLineItem) : -1;
if (selectedLineItem.BtnText == "1" && lineIndex == 0)
{
ButtonList[lineIndex] = new LineButtons() { BtnText = "0" };
}
else
ButtonList[lineIndex] = new LineButtons() { BtnText = "1" };
}
public ObservableCollection<LineButtons> ButtonList
{
get { return btnlist; }
set { btnlist = value; OnPropertyChanged("ButtonList"); }
}
public void CreateButtonList()
{
for (int i = 0; i < 32; i++)
{
ButtonList.Add(new LineButtons() { BtnText = "1"});
}
}
}
public class LineButtons : BindableBase
{
private string btnText;
public string BtnText
{
get { return btnText; }
set { btnText = value; OnPropertyChanged("BtnText"); }
}
}
I cannot get a correct selectedIndex from this code.
The second solution is to use the IsSelected/SelectedItem property instead of button command binding, I was wondering if there is conflict with the button command binding for item and IsSelected property fot listbox,so we can't use them at the same time, can someone help me out which is the best solution? Thanks in advance.

In addition to the Command property you can set the CommandParameter to the current LineButtons item (class names should be singular, names of collections use plural):
<ListBox.ItemTemplate>
<DataTemplate>
<Button Style="{StaticResource ChangeButton}"
Command="{Binding DataContext.ToggleDirectionCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType= ListBox}}"
CommandParameter="{Binding}">
<Button.Content>
<TextBlock Text="{Binding BtnText, UpdateSourceTrigger=PropertyChanged}"
TextDecorations="Underline" />
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
Then get the current item, the item that triggered the command, by accessing the command parameter:
private void Execute(object commandParameter)
{
var currentLineButton = commandParameter as LineButtons;
...
}

Returning bound checkbox values using MVVM in a WPF form

I have an object that consists of a string and an array. The string populates a ComboBox and the array populates a ListView depending on the selected string value. Each line of the ListViewconsists of a TextBlock and a CheckBox.
On submit I want to be able to verify which items have been selected for further processing but there's a disconnect when using the MVVM approach. I currently have the DataContext of the submit Button binding to the ListView but only the first value is being returned upon submit (somewhere I need to save the selected values to a list I assume but I'm not sure where). I added an IsSelected property to the model which I think is the first step, but after that I've been grasping at straws.
Model
namespace DataBinding_WPF.Model
{
public class ExampleModel { }
public class Example : INotifyPropertyChanged
{
private string _name;
private string[] _ids;
private bool _isSelected;
public bool IsSelected
{
get => _isSelected;
set
{
if (_isSelected != value)
{
_isSelected = value;
RaisePropertyChanged("IsSelected");
}
}
}
public string Name
{
get => _name;
set
{
if (_name != value)
{
_name = value;
RaisePropertyChanged("Name");
}
}
}
public string[] IDs
{
get => _ids;
set
{
if (_ids != value)
{
_ids = value;
RaisePropertyChanged("IDs");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(property));
}
}
}
}
ViewModel
namespace DataBinding_WPF.ViewModel
{
public class ExampleViewModel : INotifyPropertyChanged
{
public ObservableCollection<Example> Examples
{
get;
set;
}
// SelectedItem in the ComboBox
// SelectedItem.Ids will be ItemsSource for the ListBox
private Example _selectedItem;
public Example SelectedItem
{
get => _selectedItem;
set
{
_selectedItem = value;
RaisePropertyChanged(nameof(SelectedItem));
}
}
// SelectedId in ListView
private string _selectedId;
public string SelectedId
{
get => _selectedId;
set
{
_selectedId = value;
RaisePropertyChanged(nameof(SelectedId));
}
}
private string _selectedCheckBox;
public string IsSelected
{
get => _selectedCheckBox;
set
{
_selectedCheckBox = value;
RaisePropertyChanged(nameof(IsSelected));
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(property));
}
}
public void LoadExample()
{
ObservableCollection<Example> examples = new ObservableCollection<Example>();
examples.Add(new Example { Name = "Mark", IDs = new string[] { "123", "456" }, IsSelected = false });
examples.Add(new Example { Name = "Sally", IDs = new string[] { "789", "101112" }, IsSelected = false });
Examples = examples;
}
/* BELOW IS A SNIPPET I ADDED FROM AN EXAMPLE I FOUND ONLINE BUT NOT SURE IF IT'S NEEDED */
private ObservableCollection<Example> _bindCheckBox;
public ObservableCollection<Example> BindingCheckBox
{
get => _bindCheckBox;
set
{
_bindCheckBox = value;
RaisePropertyChanged("BindingCheckBox");
}
}
}
}
View
<UserControl x:Class = "DataBinding_WPF.Views.StudentView"
xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x = "http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc = "http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d = "http://schemas.microsoft.com/expression/blend/2008"
xmlns:local = "clr-namespace:DataBinding_WPF"
mc:Ignorable = "d"
d:DesignHeight = "300" d:DesignWidth = "300">
<Grid>
<StackPanel HorizontalAlignment = "Left" >
<ComboBox HorizontalAlignment="Left"
VerticalAlignment="Top"
Width="120"
ItemsSource="{Binding Path=Examples}"
SelectedItem="{Binding SelectedItem}"
DisplayMemberPath="Name"/>
<ListView x:Name="myListView"
ItemsSource="{Binding SelectedItem.IDs}"
DataContext="{Binding DataContext, ElementName=submit_btn}"
SelectedItem="{Binding SelectedId}"
Height="200" Margin="10,50,0,0"
Width="Auto"
VerticalAlignment="Top"
Background="AliceBlue">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" >
<CheckBox
Name="myCheckBox"
IsChecked="{Binding IsSelected,
RelativeSource={RelativeSource AncestorType=ListViewItem}}"
Margin="5, 0"/>
<TextBlock Text="{Binding}" FontWeight="Bold" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button HorizontalAlignment="Left" Height="20" Width="100"
Click="Submit" x:Name="submit_btn">Submit</Button>
</StackPanel>
</Grid>
</UserControl>
View.cs
namespace DataBinding_WPF.Views
{
/// <summary>
/// Interaction logic for StudentView.xaml
/// </summary>
public partial class StudentView : UserControl
{
public StudentView()
{
InitializeComponent();
}
private void Submit(object sender, EventArgs e)
{
var selectedItems = ((Button)sender).DataContext;
// process each selected item
// foreach (var selected in ....) { }
}
}
}

The ListView control already exposes a selected items collection as property SelectedItems.
private void Submit(object sender, RoutedEventArgs e)
{
var selectedIds = myListView.SelectedItems.Cast<string>().ToList();
// ...do something with the items.
}
However, I doubt that you want to do this in the code-behind, but rather in the view model. For this purpose, WPF offers the concept of commands.
MVVM - Commands, RelayCommands and EventToCommand
What you need is a relay command or delegate command (the name varies across frameworks). It encapsulates a method that should be executed for e.g. a button click and a method to determine whether the command can be executed as an object that can be bound in the view. Unfortunately, WPF does not provide an implementation out-of-the-box, so you either have to copy an implementation like here or use an MVVM framework that already provides one, e.g. Microsoft MVVM Tookit.
You would expose a property Submit of type ICommand in your ExampleViewModel and initialize it in the constructor with an instance of RelayCommand<T> that delegates to a method to execute.
public class ExampleViewModel : INotifyPropertyChanged
{
public ExampleViewModel()
{
Submit = new RelayCommand<IList>(ExecuteSubmit);
}
public RelayCommand<IList> Submit { get; }
// ...other code.
private void ExecuteSubmit(IList selectedItems)
{
// ...do something with the items.
var selectedIds = selectedItems.Cast<string>().ToList();
return;
}
}
In your view, you would remove the Click event handler and bind the Submit property to the Command property of the Button. You can also bind the SelectedItems property of the ListView to the CommandParameter property, so the selected items are passed to the command on execution.
<Button HorizontalAlignment="Left"
Height="20"
Width="100"
x:Name="submit_btn"
Command="{Binding Submit}"
CommandParameter="{Binding SelectedItems, ElementName=myListView}">Submit</Button>
Additionally, a few remarks about your XAML.
Names of controls in XAML should be Pascal-Case, starting with a capital letter.
You should remove the DataContext binding from ListView completely, as it automatically receives the same data context as the Button anyway.
DataContext="{Binding DataContext, ElementName=submit_btn}"
You can save yourself from exposing and binding the SelectedItem property in your ExampleViewModel, by using Master/Detail pattern for hierarchical data.
<Grid>
<StackPanel HorizontalAlignment = "Left" >
<ComboBox HorizontalAlignment="Left"
VerticalAlignment="Top"
Width="120"
ItemsSource="{Binding Path=Examples}"
IsSynchronizedWithCurrentItem="True"
DisplayMemberPath="Name"/>
<ListView ItemsSource="{Binding Examples/IDs}"
SelectedItem="{Binding SelectedId}"
Height="200" Margin="10,50,0,0"
Width="Auto"
VerticalAlignment="Top"
Background="AliceBlue">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" >
<CheckBox Name="myCheckBox"
IsChecked="{Binding IsSelected, RelativeSource={RelativeSource AncestorType=ListViewItem}}"
Margin="5, 0"/>
<TextBlock Text="{Binding}"
FontWeight="Bold" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button HorizontalAlignment="Left"
Height="20"
Width="100"
Command="{Binding Submit}"
CommandParameter="{Binding SelectedItems, ElementName=myListView}">Submit</Button>
</StackPanel>
</Grid>

If the view's data context is bound to the view then remove the DataContext from the ListView.
You could remove the item template and instead use a GridView like:
<ListView.View>
<GridView >
<GridViewColumn Header="Selected" >
<GridViewColumn.CellTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsSelected}" Content="{Binding Name}" />
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
</GridView>
</ListView.View>
Since the ItemSource is an Observable collection, there are several options to monitor changes in the checkboxes:
Add an event handler to the item changed event of the collection and then you can add the Name or the collection index to a local collection. e.g Examples[e.CollectionIndex].Name
Alternatively iterate over the observable collection and select those Examples where Selected = "true"

How to access checkbox in ListBox items

I'm trying to make a ListBox with checkboxes into it.
In xaml I have:
<ListBox ItemsSource="{StaticResource ResourceKey=lstMaterialesCL}" SelectionMode="Multiple" Name="lstMaterial" >
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox Name="chkMaterial" Content="{Binding DescCompuesta}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
and my ListBox looks as:
It is ok, but look it, when I checked "Municipales" the item in the ListBox is not selected, and when I select in the ListBox "Industriales" it is not checked
If I inspect the items selected into the ListBox it don't coincide with the items Checked
foreach (var item in lstMaterial.SelectedItems)
{
MessageBox.Show(((MaterialesCL)item).DescCompuesta);
}
It shows me "Oficiales", "Industriales" and "Destrucciones" but the user was want select "Municipales" and "Destrucciones"
How I can to make coincide the ListBox items selected with the CheckBox checked if the CheckBox checked is mandatory?

XAML:
DescCompuestaList is a list of CheckListGeneric
<ListBox ItemsSource="{Binding DescCompuestaList}" >
<ListBox.ItemTemplate>
<HierarchicalDataTemplate>
<CheckBox Content="{Binding DescCompuesta}" IsChecked="{Binding IsChecked}"/>
</HierarchicalDataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Here your CheckListGeneric class
public class CheckListGeneric: ViewModelBase
{
#region ..:: Fields ::..
private bool _isChecked;
#endregion
#region ..:: Properties ::..
public long Id { get; set; }
public string DescCompuesta{ get; set; }
public bool IsChecked
{
get { return _isChecked; }
set { _isChecked = value; OnPropertyChanged("IsChecked"); }
}
#endregion
}
You can get all selected using a simple query
var selectedItems = DescCompuestaList.Where(x => x.IsChecked)
simple as life.

How about binding CheckBox's IsChecked property to ListBoxItem's IsSelected property.
Something like: IsChecked={Binding IsSelected, RelativeSource={RelativeSource AncestorType={x:Type ListBoxItem}}}
In your example:
<ListBox ItemsSource="{StaticResource ResourceKey=lstMaterialesCL}" SelectionMode="Multiple" Name="lstMaterial" >
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox Name="chkMaterial" Content="{Binding DescCompuesta}" IsChecked={Binding IsSelected, RelativeSource={RelativeSource AncestorType={x:Type ListBoxItem}}}/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>

For me it's always easiest way to use Blend for making templates.
Open project in blend and make one listBox, then select that ListBox and add template like in picture.
just to show purpose i have add simple checkBox and TextBlock, and you can make it as u like it.
in ViewModel i have made simple observable collection just to show purpose and bound ItemsSource to Users:
public class TestVM
{
public ObservableCollection<User> Users { get; set; }
public TestVM()
{
Users = new ObservableCollection<User>
{
new User{ IsChecked=true, Name="User1" },
new User{ IsChecked=false, Name="User2" },
new User{ IsChecked=true, Name="User3" },
new User{ IsChecked=false, Name="User3" },
};
}
}
public class User
{
public bool IsChecked { get; set; }
public string Name { get; set; }
}
This way you can make any template you like.

Wow, I tested all your suggestions, thank you so much to all, after all tests, the solution how I need it is more or less like this:
On xaml:
<StackPanel Orientation="Horizontal">
<ListBox ItemsSource="{Binding MaterialesVM}" SelectionMode="Multiple"
Name="ListBoxMateriales" Width="300" Height="200"
HorizontalAlignment="Left" VerticalAlignment="Top">
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="IsSelected" Value="{Binding IsChecked, Mode=TwoWay}" />
</Style>
</ListBox.ItemContainerStyle>
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsChecked, Mode=TwoWay}"
Content="{Binding DescCompuesta}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Button Name="btnPrueba" Style="{StaticResource BotonContent}"
Content="Selected" Width="80" Height="30" HorizontalAlignment="Left"
VerticalAlignment="Top"
Margin="10,0,0,0" Click="btnPrueba_Click"/>
<Button Name="btnLimpia" Style="{StaticResource BotonRechazar}"
Width="30" Height="30" Click="btnLimpia_Click" HorizontalAlignment="Left"
VerticalAlignment="Top"
Margin="5,0,0,0" ToolTipService.ToolTip="Limpia Todos"/>
<Button Name="btnMarca" Style="{StaticResource BotonAceptar}"
Width="30" Height="30" Click="btnMarca_Click" HorizontalAlignment="Left"
VerticalAlignment="Top"
Margin="5,0,0,0" ToolTipService.ToolTip="Selecciona Todos"/>
</StackPanel>
On this way I don't care on where clicked, the item will be selected or un-selected (on the CheckBox and on the ListItem)
And to see the items selected:
// To show the selected items
private void btnPrueba_Click(object sender, RoutedEventArgs e)
{
var selectedItems = MaterialesVM.Where(x => x.IsChecked);
foreach (var item in selectedItems)
{
MessageBox.Show(((MaterialesCL)item).DescCompuesta);
}
}
To select all items:
// To select all items
private void btnMarca_Click(object sender, RoutedEventArgs e)
{
var Items = ListBoxMateriales.Items;
foreach (MaterialesCL item in Items)
{
item.IsChecked = true;
}
}
To un-select all items:
// To un-select all items
private void btnLimpia_Click(object sender, RoutedEventArgs e)
{
var Items = ListBoxMateriales.Items;
foreach (MaterialesCL item in Items)
{
item.IsChecked = false;
}
}
and my classes are:
MaterialesCL.cs
public class MaterialesCL : INotifyPropertyChanged
{
public int Material { get; set; }
public string Descripcion { get; set; }
public string DescCompuesta { get; set; }
private bool _ischecked;
public bool IsChecked
{
get { return _ischecked; }
set
{
_ischecked = value;
OnPropertyChanged("IsChecked");
}
}
#region PropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
LstMaterialesCL.cs
public class LstMaterialesCL : ObservableCollection<MaterialesCL>, INotifyPropertyChanged
{
public LstMaterialesCL()
{
BasculaEntities _context = new BasculaEntities();
var Query = (from m in _context.Materiales
select new { m.Material, m.Descripcion}
).OrderBy(m => m.Material).ToList();
foreach (var item in Query)
{
this.Add(new MaterialesCL { Material = item.Material,
Descripcion = item.Descripcion, DescCompuesta = item.Material.ToString("000") + " - " + item.Descripcion,
IsChecked=false});
}
}
}
and on my UserControl MaterialesVM is an instance of LstMaterialesCL
LstMaterialesCL MaterialesVM = new LstMaterialesCL();
and so my test of ListBox with CheckBoxes works as I need.
Thank to all you I has learn so much.

WPF Tabcontrol (TabItem Content is not appearing)

I implemented a TabControl with Closable TabItems in my App. For this, I am using a Collection which I fill with the SubMenuItems of MenuItem "Öffne", which are bound to ICommands in the MainViewModel.
So if I click on MenuItem "Open Tab1", then the header of Tab 1 is created, but I can not see any content. The content of the TabItem is shown AFTER I click on the Header of the TabItem. But I want it to be shown directly when the TabItem is "created" without any need of clicking on the header. Closing the TabItems from the "X" button works fine.
I looked at a couple of examples and tried a ContentTemplate, but it didn't work (Maybe I made something wrong?).
I Hope you can tell me what i have done wrong or show me a good example.
Thanks in advance!
Here are my code snippets:
MainWindow.XAML:
<Window.Resources>
<vm:MainViewModel x:Key="viewModel"/>
</Window.Resources>
<TabControl Background="#FFE5E5E5" ItemsSource="{Binding TabControlViews}" SelectedItem="{Binding CurrentTabItem}" Margin="0,21,0,0">
<TabControl.ItemTemplate>
<DataTemplate>
<DockPanel Width="120">
<TextBlock Text="{Binding Header}"/>
<Button
Command="{Binding ParameterizedCommand, Source={StaticResource viewModel}}"
CommandParameter="{Binding Header, RelativeSource={RelativeSource AncestorType={x:Type TabItem}}}"
Content="X"
Cursor="Hand"
DockPanel.Dock="Right"
Focusable="False"
FontFamily="Courier"
FontSize="9"
FontWeight="Bold"
Margin="0,1,0,0"
Padding="0"
VerticalContentAlignment="Bottom"
Width="16" Height="16" />
<ContentPresenter
Content="{Binding Path=DisplayName}"
VerticalAlignment="Center" />
</DockPanel>
</DataTemplate>
</TabControl.ItemTemplate>
<!--<TabControl.ContentTemplate>
<DataTemplate>
</DataTemplate>
</TabControl.ContentTemplate>-->
<TabControl.Resources>
<DataTemplate x:Name="test" DataType="{x:Type vm:MenueVM}">
<cu:MenueSearch/>
</DataTemplate>
<DataTemplate DataType="{x:Type vm:FieldPointsVM}">
<cu:FieldPointsSearch/>
</DataTemplate>
<DataTemplate DataType="{x:Type vm:DataTransferVM}">
<cu:DataTransfer/>
</DataTemplate>
</TabControl.Resources>
</TabControl>
MainWindow.cs:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
var vm = (MainViewModel)Resources["viewModel"];
this.DataContext = vm;
}
}
MainViewModel.cs:
public MainViewModel()
{
TabControlViews = new ObservableCollection<BaseViewModel>();
_menueVM = new MenueVM("Menüpunkte", "Menue");
_fieldVM = new FieldPointsVM("Feldpunkte", "FieldPoint");
_dataVM = new DataTransferVM("DatenTransfer", "DataTransfer");
ParameterizedCommand = new RelayCommand(DoParameterizedCommand);
}
private void DoParameterizedCommand(object parameter)
{
if (parameter.ToString() == "App.ViewModel.MenueVM")
{
TabControlViews.Remove(_menueVM);
}
else if (parameter.ToString() == "App.ViewModel.FieldPointsVM")
{
TabControlViews.Remove(_fieldVM);
}
else if (parameter.ToString() == "App.ViewModel.DataTransfer")
{
TabControlViews.Remove(_dataVM);
}
}
private ICommand _parameterizedCommand;
public ICommand ParameterizedCommand
{
get
{
return _parameterizedCommand;
}
set
{
_parameterizedCommand = value;
}
}
private TabItem _propCurrentTabItem;
public TabItem CurrentTabItem
{
get
{
return _propCurrentTabItem;
}
set
{
_propCurrentTabItem = value;
}
}
private ObservableCollection<BaseViewModel> _TabControlViews = new ObservableCollection<BaseViewModel>();
public ObservableCollection<BaseViewModel> TabControlViews
{
get
{
return _TabControlViews;
}
set
{
_TabControlViews = value;
OnPropertyChanged();
}
}
public ICommand OpenMenupunkteCommand
{
get
{
return new BaseCommand(OpenMenuPunkte);
}
}
public ICommand OpenFeldpunkteCommand
{
get
{
return new BaseCommand(OpenFeldpunkte);
}
}
public ICommand OpenDataTransferCommand
{
get
{
return new BaseCommand(OpenDataTransfer);
}
}
private void OpenMenuPunkte()
{
if (!TabControlViews.Contains(_menueVM))
{
TabControlViews.Add(_menueVM);
}
}
private void OpenFeldpunkte()
{
if (!TabControlViews.Contains(_fieldVM))
{
TabControlViews.Add(_fieldVM);
}
}
private void OpenDataTransfer()
{
if (!TabControlViews.Contains(_dataVM))
{
TabControlViews.Add(_dataVM);
}
}
MenueVM.cs
public class MenueVM : BaseViewModel
{
public MenueVM()
{
//Here are some actions done for Data, but I think they are unimportant for this question
}
public MenueVM(string header, string content)
{
Header = header;
Content = content;
}
private string _header;
public string Header
{
get
{
return _header;
}
set
{
_header = value;
}
}

Still time to post an answer?
Try this :
XAML:
<TabControl ItemsSource="{Binding....}" IsSynchronizedWithCurrentItem="True">
<!-- style, template, ... -->
</TabControl>
CS:
//Adding your viewModel to your ObservableCollection<> TabControlViews
TabControlViews.Add(_viewModelToAdd);
ICollectionView collectionView = CollectionViewSource.GetDefaultView(TabControlViews);
if (collectionView != null)
{
collectionView.MoveCurrentTo(_viewModelToAdd);
//And this is because you don't want your tabItem to be selected :
collectionView.MoveCurrentToPrevious();
}
Found in the downloadable DemoMVVMApp here : https://msdn.microsoft.com/en-us/magazine/dd419663.aspx#id0090030
I've also spent a huge amount of time to solve this problem... ;-)

The problem is that your tab is been created, but it´s not been selected. So, in addition to calling
TabControlViews.Add(_dataVM)
, you should also update your CurrentTabItem
CurrentTabItem = _dataVM;
and bind your TabControl SelectedItem property to your CurrentTabItem, like this:
<TabControl ItemsSource="{Binding TabControlViews}" SelectedItem="{Binding CurrentTabItem}">
Also, if you remove a TabItem and want to get back to the last one, you have to call
CurrentTabItem = TabControlViews.LastOrDefault();

Wpf MVVM - Tabbed interface is not working as expected

First: I am new to MVVM and WPF.
I am trying to create a little application with a tabbed user interface. Users can create products and storage locations, using a button which should open a new TabItem.
My code in the view looks like this:
<TabControl ItemsSource="{Binding Workspaces}"
IsSynchronizedWithCurrentItem="True"
Margin="3"
DockPanel.Dock="Top">
<TabControl.ItemTemplate>
<DataTemplate>
<Label Content="{Binding DisplayName}" />
</DataTemplate>
</TabControl.ItemTemplate>
</TabControl>
and the View Model is this:
ObservableCollection<WorkspaceViewModel> _workspaces;
public ObservableCollection<WorkspaceViewModel> Workspaces
{
get
{
if (_workspaces == null)
{
_workspaces = new ObservableCollection<WorkspaceViewModel>();
}
return _workspaces;
}
set
{
_workspaces = value;
}
}
public void AddProduct(object obj)
{
Workspaces.Add(new ProductViewModel());
}
Various other buttons add different ViewModels to the Workspaces Collection.
I have defined multiple Data Template (one for each ViewModel). Here is one:
<DataTemplate DataType="{x:Type vm:ProductViewModel}">
<vw:ProductView />
</DataTemplate>
The WorkspaceViewModel is this:
namespace Inventory.Desktop.ViewModels
{
public abstract class WorkspaceViewModel : INotifyPropertyChanged
{
#region Events and EventHandlers
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
}
and eg the ProductViewModel
namespace Inventory.Desktop.ViewModels
{
public class ProductViewModel: WorkspaceViewModel
{
private Product _product;
private string _displayName;
public string DisplayName
{
get
{
if (String.IsNullOrEmpty(_displayName))
{
return "Neues Produkt";
} else
{
return _displayName;
}
}
set
{
_displayName = value;
NotifyPropertyChanged("DisplayName");
}
}
#region Public Properties
public Product Product
{
get
{
return _product;
}
set
{
_product = value;
NotifyPropertyChanged("Product");
}
}
public string Title
{
get
{
return _product.Title;
}
set
{
_product.Title = value;
NotifyPropertyChanged("Title");
}
}
public string ScanCode
{
get
{
return _product.ScanCode;
}
set
{
_product.ScanCode = value;
NotifyPropertyChanged("ScanCode");
}
}
public string Manufacturer
{
get
{
return _product.Manufacturer;
}
set
{
_product.Manufacturer = value;
NotifyPropertyChanged("Manufacturer");
}
}
public string ManufacturerNumber
{
get
{
return _product.ManufacturerNumber;
}
set
{
_product.ManufacturerNumber = value;
NotifyPropertyChanged("ManufacturerNumber");
}
}
public string Description
{
get
{
return _product.Description;
}
set
{
_product.Description = value;
NotifyPropertyChanged("Description");
}
}
#endregion
#region Commands
private ICommand _saveCommand;
public ICommand SaveCommand
{
get
{
return _saveCommand;
}
set
{
_saveCommand = value;
}
}
#endregion
#region Command Executions
public void Save(object obj)
{
using (var db = new InvContext())
{
db.Products.Attach(Product);
db.Entry(Product).State = Product.ProductId == 0 ?
EntityState.Added : EntityState.Modified;
db.SaveChanges();
}
MessageBox.Show("Product saved: " + Product.Title);
}
#endregion
#region Constructors
public ProductViewModel()
{
if (_product == null)
{
_product = new Product();
}
SaveCommand = new RelayCommand(new Action<object>(Save));
}
#endregion
}
}
Here the ProductView.xaml view:
<UserControl x:Class="Inventory.Desktop.Views.ProductView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="400" d:DesignWidth="450">
<DockPanel>
<StackPanel DockPanel.Dock="Top" Orientation="Horizontal" FlowDirection="RightToLeft">
<Button Name="SaveProductButton" Command="{Binding SaveCommand}" Content="Speichern" Margin="3" BorderThickness="0">
</Button>
</StackPanel>
<StackPanel DockPanel.Dock="Top" VerticalAlignment="Stretch">
<Label Content="Scan Code" />
<TextBox Text="{Binding Path=ScanCode}" HorizontalAlignment="Stretch" Margin="3" Padding="3" Height="50" TextAlignment="Right">
<TextBox.Background>
<ImageBrush ImageSource="..\Images\Barcode32.png" AlignmentX="Left" Stretch="None" />
</TextBox.Background>
</TextBox>
<Label Content="Bezeichnung" />
<TextBox Text="{Binding Path=Title, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
<Label Content="Hersteller" />
<TextBox Text="{Binding Path=Manufacturer, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
<Label Content="Hersteller Nummer" />
<TextBox Text="{Binding Path=ManufacturerNumber, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
<Label Content="Beschreibung / Information" />
<TextBox Text="{Binding Path=Description, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Stretch" Margin="3" />
</StackPanel>
</DockPanel>
</UserControl>
and here the code-behind ProductView.xaml.cs:
namespace Inventory.Desktop.Views
{
/// <summary>
/// Interaktionslogik für ProductView.xaml
/// </summary>
public partial class ProductView : UserControl
{
ProductViewModel _productModel = new ProductViewModel();
public ProductView()
{
InitializeComponent();
base.DataContext = _productModel;
}
}
}
What's currently working:
When I click a button, I got a new TabItem displaying the correct view and all commands work correctly.
What's not working:
When I open a TabItem, enter some information, and then I open another TabItem with a different ViewModel, switching the focus to the new TabItem and then back to the original oen, then all entered information are gone (object is null).
When I open a TabItem, enter some information, and then I open another TabItem with the same ViewModel, then both TabItems show the the same information.
When I add a new TabItem, it doesn't get focus.
I am totally lost and I hope you can tell me what I am doing wrong.
Best
Stefan

Have a property on your ViewModel to store the reference to current/selected tab
public WorkspaceViewModel SelectedTab
{
get { return _selectedTab; }
set
{
_selectedTab = value;
RaisePropertyChanged(() => SelectedTab);
}
}
and bind this to SelectedItem property on TabControl.
<TabControl ItemsSource="{Binding Workspaces}"
SelectedItem="{Binding SelectedTab, Mode=TwoWay}"
Margin="3"
DockPanel.Dock="Top">
<TabControl.ItemTemplate>
<DataTemplate>
<Label Content="{Binding DisplayName}" />
</DataTemplate>
</TabControl.ItemTemplate>
</TabControl>
And finally, you want to update SelectedTab property whenever you are adding a new tab. Modify your AddProduct like this:
public void AddProduct(object obj)
{
var workspace = new ProductViewModel();
Workspaces.Add(workspace);
SelectedTab = workspace;
}