Show List in xaml using ViewModel

Show List in xaml using ViewModel - c#

I have a UserControl called "UserControllerIo" and this is what it has:
public ObservableCollection<string> Messages { get; set; }
public UserControllerIo()
{
Messages = new ObservableCollection<string>();
InitializeComponent();
IoComponentViewModel.Instance = new IoComponentViewModel();
Label1.DataContext = IoComponentViewModel.Instance;
Messages.Add(Label1.Text);
}
I consume this in my xml like so:
<Grid>
<Label>
<TextBlock x:Name="Label1" TextWrapping="WrapWithOverflow"
Text="{Binding Path=XState, Mode=OneWay}">
</TextBlock>
</Label>
<ListView
x:Name="ListView"
ItemsSource="{Binding Messages}" />
</Grid>
I have a view model for this control:
class IoComponentViewModel : INotifyPropertyChanged
{
public static IoComponentViewModel Instance { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
private string _xState;
public string XState
{
get { return _xState; }
set
{
_xState = value;
OnPropertyChanged($"XState");
}
}
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
And I invoke to populate the list on another class like so:
case x:
IoComponentViewModel.Instance.XState = msg;
break;
My problem is, it is not showing in my Listview although I can see it in my label. Can you please show me how. Thank you.

I don't know how much I understood your task from the provided code, but look at this implementation variant.
IoComponentViewModel:
public class IoComponentViewModel : INotifyPropertyChanged
{
public static IoComponentViewModel Instance { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
private string _xState;
public string XState
{
get { return _xState; }
set
{
if (_xState == value)
return;
XStates.Add(_xState = value);
OnPropertyChanged($"XState");
}
}
public ObservableCollection<string> XStates { get; } = new ObservableCollection<string>();
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
XAML:
<Grid x:Name="PART_Grid">
<Grid.DataContext>
<local:IoComponentViewModel/>
</Grid.DataContext>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<!--<Label>-->
<TextBlock x:Name="Label1" TextWrapping="WrapWithOverflow"
Text="{Binding XState, Mode=OneWay}">
</TextBlock>
<!--</Label>-->
<ListView Grid.Row="1"
x:Name="ListView"
ItemsSource="{Binding XStates}" />
</Grid>
Code Behind:
//public ObservableCollection<string> Messages { get; set; }
public UserControllerIo()
{
//Messages = new ObservableCollection<string>();
InitializeComponent();
// IoComponentViewModel.Instance = new IoComponentViewModel();
//Label1.DataContext = IoComponentViewModel.Instance;
IoComponentViewModel.Instance = (IoComponentViewModel)PART_Grid.DataContext;
//Messages.Add(Label1.Text);
}

I misread the question initially. There are two problems. Your list is not binding to the view model, so you need an element reference.
<UserControl x:Class="StackOverflow.UserControllerIo"
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:StackOverflow"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800"
x:Name="MyUserControl"
>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<Label>
<TextBlock Foreground="Black" x:Name="Label1" TextWrapping="WrapWithOverflow"
Text="{Binding Path=XState, Mode=OneWay}">
</TextBlock>
</Label>
<ListView Grid.Row="1"
x:Name="ListView"
ItemsSource="{Binding Messages, ElementName=MyUserControl}" >
</ListView>
</Grid>
Secondly, at the point where you add Label1.Text to your data binding is not ready. So you will need to wait for binding before you read the text, for example in load event like this:
public partial class UserControllerIo : UserControl
{
public ObservableCollection<string> Messages { get; set; }
public UserControllerIo()
{
Messages = new ObservableCollection<string>();
InitializeComponent();
IoComponentViewModel.Instance = new IoComponentViewModel();
Label1.DataContext = IoComponentViewModel.Instance;
IoComponentViewModel.Instance.XState = "Something";
Loaded += UserControllerIo_Loaded;
}
private void UserControllerIo_Loaded(object sender, RoutedEventArgs e)
{
Messages.Add(Label1.Text);
}
}

EDIT:
my first tests mislead me, by testing with an int property for adding values to the List on runtime.
ObservableCollection updates anyway!
The problem is how you declared the Messages Property. If you have a Property on a Control it needs to be a dependency Property to notify the UI.
replace
public ObservableCollection<string> Messages { get; set; }
with
public ObservableCollection<string> Messages
{
get { return (ObservableCollection<string>)GetValue(MessagesProperty); }
set { SetValue(MessagesProperty, value); }
}
public static readonly DependencyProperty MessagesProperty =
DependencyProperty.Register("Messages", typeof(ObservableCollection<string>), typeof(UserControllerIo), new PropertyMetadata(null));
and you should be fine.
OR
you could imlpement INotifyPropertyChanged on your UserControl class.
And don't forget to maintain #Clemens' comment about binding!!!
ItemsSource="{Binding Messages, RelativeSource={RelativeSource AncestorType=UserControl}}

Related

INotifyPropertyChanged in wpf application of List

Problem
I want to refresh my wpf view when a change is made in a List of objects in my application, but it wont register the INotifyChanged method when I change a value.
What I've tried
I went to multiple different stackoverflow pages with sort of the same problem but I don't get it working right. It wont register a change in a object in the list.
my code
below is the code for the MainWindow of the WPF application in wher with the last button click I change the value of XLocation in an object out of a list.
public partial class MainWindow : Window
{
private string filePathArtist { get; set; }
private string filePathGrid { get; set; }
public Game.Game Game { get; set; }
public MainWindow()
{
InitializeComponent();
filePathGrid = String.Empty;
filePathArtist = String.Empty;
}
private void BtnOpen_Click(object sender, RoutedEventArgs e)
{
OpenFileDialog openFileDialog = new OpenFileDialog();
bool? res = openFileDialog.ShowDialog();
if (res == true)
{
string filepathgrid = openFileDialog.FileName;
filePathGrid = filepathgrid;
GridTextBox.Text = filepathgrid;
}
}
private void PickArtistBtn_Click(object sender, RoutedEventArgs e)
{
OpenFileDialog openFileDialog = new OpenFileDialog();
bool? res = openFileDialog.ShowDialog();
if (res == true)
{
string filepathartist = openFileDialog.FileName;
filePathArtist = filepathartist;
ArtistTextBox.Text = filepathartist;
}
}
private void CreateGridBtn_Click(object sender, RoutedEventArgs e)
{
Game = new Game.Game(filePathGrid, filePathArtist);
this.DataContext = Game;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
Game.Artists[0].XLocation = 30;
}
}
Next code is the Game class where is implemented a INotfyPropertyChanged on the list of Artists.
public class Game : INotifyPropertyChanged
{
public List<Artist> _artists;
public List<Artist> Artists
{
get
{
return _artists;
}
set
{
_artists = value;
OnPropertyChanged("Artists");
}
}
public List<ITile> Tiles { get; set; }
public Game()
{
}
public Game(string graphPath, string artistPath)
{
IDataParser graphParser = DataFactory.DataFactory.Instance.CreateParser(graphPath);
IDataParser artistParser = DataFactory.DataFactory.Instance.CreateParser(artistPath);
Tiles = graphParser.ParseGridData(graphPath);
Artists = artistParser.ParseArtistData(artistPath);
Test = "new Game";
}
public string Test { get; set; } = "t";
public event PropertyChangedEventHandler? PropertyChanged;
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Ive also added the INotifyPropertyChanged in the Artists class
public class Artist : INotifyPropertyChanged
{
private float _xLocation;
private float _yLocation;
private int _xVelocity;
private int _yVelocity;
public float XLocation
{
get => _xLocation;
set
{
_xLocation = value;
OnPropertyChanged("XLocation");
}
}
public float ConvertedXLoc
{
get => XLocation * (float)3.75;
set { }
}
public float YLocation
{
get => _yLocation;
set
{
_yLocation = value;
OnPropertyChanged("YLocation");
}
}
public float ConvertedYLoc
{
get => YLocation * (float)3.75;
set { }
}
public int XVelocity
{
get => _xVelocity;
set
{
_xVelocity = value;
}
}
public int YVelocity
{
get => _yVelocity;
set
{
_yVelocity = value;
}
}
public event PropertyChangedEventHandler? PropertyChanged;
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Then here is the Xaml code where I bind the objects to the wpf UI.
<Window x:Class="BroadwayBoogie.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:game="clr-namespace:BroadwayBoogie.Game"
mc:Ignorable="d"
Title="MainWindow" Height="900" Width="900"
>
<Window.DataContext>
<game:Game/>
</Window.DataContext>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="201*"/>
<ColumnDefinition Width="199*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="21*"/>
<RowDefinition Height="401*"/>
<RowDefinition Height="20*"/>
</Grid.RowDefinitions>
<Button x:Name="BtnOpen" Content="Pick Grid" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Click="BtnOpen_Click"/>
<TextBox x:Name="GridTextBox" HorizontalAlignment="Center" TextWrapping="NoWrap" VerticalAlignment="Center" Width="266" />
<Button x:Name="PickArtistBtn" Content="Pick Artist" HorizontalAlignment="Left" Margin="356,0,0,0" VerticalAlignment="Center" Click="PickArtistBtn_Click" RenderTransformOrigin="-0.135,0.647"/>
<TextBox x:Name="ArtistTextBox" HorizontalAlignment="Left" Margin="30,14,0,0" TextWrapping="NoWrap" VerticalAlignment="Top" Width="231" Grid.Column="1"/>
<Button x:Name="CreateGridBtn" Grid.Column="1" Content="Create Grid" HorizontalAlignment="Left" Margin="311,14,0,0" VerticalAlignment="Top" Click="CreateGridBtn_Click"/>
<Canvas Width="800" Height="800" Grid.ColumnSpan="2" Margin="49,15,51,27" Grid.Row="1" Background="DarkSeaGreen" Grid.RowSpan="2">
<ItemsControl Name="tilesItemsControl" ItemsSource="{Binding Tiles}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Canvas>
<Rectangle
Width="15"
Height="15"
Fill="{Binding Color}"
Canvas.Left ="{Binding ConvertedXLoc}"
Canvas.Top="{Binding ConvertedYLoc}" />
</Canvas>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
<ItemsControl Name="ArtistItemsControl" ItemsSource="{Binding Artists}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Canvas>
<Rectangle
Width="3.75"
Height="3.75"
Fill="Black"
Canvas.Left ="{Binding ConvertedXLoc}"
Canvas.Top="{Binding ConvertedYLoc}" />
</Canvas>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Canvas>
<Grid/>
<Button Content="Button" HorizontalAlignment="Left" Margin="4,0,0,0" Grid.Row="2" VerticalAlignment="Center" Click="Button_Click"/>
</Grid>
So with the press of the button I added for testing purposes. It changes a value in the List and then the PropertyChanged method should detect that but it doesn't detect it it just skips it.
Question
So my basic question is, how do I detect the change of a property from objects out of the List of Artists.

OnPropertyChanged will only be executed when the property itself is changed. A new item in a list is not a property change. That's the reason why no updates happens.
Instead a List, try an ObservableCollection. An ObservableCollection implements an additional INotifyCollectionChanged which makes the UI able to react on changing items in the list.

UWP TextBlock Text doesn't change

My goal was to make a list of selectable shows where the user can pick one, then edit data about it in the right panel.
I have an ObservableCollection that is bound to a ListView. The test Shows appear correctly. I also have a Show SelectedShow that is bound using Mode.TwoWay. When I select a different Show in the ListView, I receive the corresponding debug statement.
The TextBlock's Text does not change when I click different Shows in the ListView.
Any ideas?
MainPage.xaml:
<Page
x:Class="PlexHelper.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:PlexHelper"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="2*"></ColumnDefinition>
<ColumnDefinition Width="6*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"></RowDefinition>
</Grid.RowDefinitions>
<StackPanel Orientation="Vertical">
<TextBox HorizontalAlignment="Stretch" Text="" PlaceholderText="Search shows..."/>
<ListView ItemsSource="{x:Bind Shows}" SelectedItem="{x:Bind SelectedShow, Mode=TwoWay}" SelectionChanged="OnSelectionChanged">
<ListView.ItemTemplate>
<DataTemplate x:DataType="local:Show">
<TextBlock Text="{x:Bind Name, Mode=OneWay}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
<TextBlock Grid.Column="1" FontSize="50" HorizontalAlignment="Center" VerticalAlignment="Center" Text="{x:Bind SelectedShow.Name, Mode=OneWay}"></TextBlock>
</Grid>
</Page>
MainPage.xaml.cs:
using System.Collections.ObjectModel;
using System.Diagnostics;
using Windows.UI.Xaml.Controls;
namespace PlexHelper
{
public sealed partial class MainPage : Page
{
public ObservableCollection<Show> Shows { get; } = new ObservableCollection<Show>();
public Show SelectedShow { get; set; }
public MainPage()
{
this.InitializeComponent();
Shows.Add(new Show("Show 1"));
Shows.Add(new Show("Show 2"));
Shows.Add(new Show("Show 3"));
SelectedShow = Shows[0];
}
private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
{
Debug.WriteLine("now selected: " + SelectedShow.Name);
}
}
}
Show.cs:
using System.ComponentModel;
using System.Runtime.CompilerServices;
namespace PlexHelper
{
public class Show : INotifyPropertyChanged
{
private string _name;
public string Name
{
get => _name;
set
{
if (_name != value)
{
_name = value;
OnPropertyChanged();
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
public Show(string name = "Default Show Name")
{
Name = name;
}
public void OnPropertyChanged([CallerMemberName] string propertyName = null) =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}

You need to raise PropteryChanged event for SelectedShow as well in order to reflect it on UI.
Your MainPlage should look like this:
public sealed partial class MainPage : Page, INotifyPropertyChanged
{
public ObservableCollection<Show> Shows { get; } = new ObservableCollection<Show>();
private Show _selectedShow;
public Show SelectedShow
{
get => _selectedShow;
set
{
if (_selectedShow != value)
{
_selectedShow = value;
OnPropertyChanged();
}
}
}
public MainPage()
{
this.InitializeComponent();
Shows.Add(new Show("Show 1"));
Shows.Add(new Show("Show 2"));
Shows.Add(new Show("Show 3"));
SelectedShow = Shows[0];
}
private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
{
Debug.WriteLine("now selected: " + SelectedShow.Name);
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string propertyName = null) =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
I would better recommend creating a ViewModel which contains the list of Shows along with the SelectedShow and Implement INotifyPropertyChanged in that VM.

C# WPF - ComboBox of databound ObservableCollection of classes

Recently I started converting a proof of concept UWP app to a working WPF app.
What I want is to have two dropdowns (combobox) of "characters" I can choose, I want them databound to an ObservableCollection property, where the characters I selected is stored in a different Character property for player 1 then player 2.
I had databinding on dropdowns working in the UWP app, but I can't get it to work in the WPF app.
In the WPF app, the comboboxes stay empty and I can't select an option.
I tried following the answer to this question, but I think I'm missing something: Binding a WPF ComboBox to a custom list
Here is the code, kept minimal:
Character.cs
public class Character : INotifyPropertyChanged
{
private int _id;
public int Id
{
get
{
return _id;
}
set
{
_id = value;
}
}
private string _name;
public string Name
{
get
{
return _name;
}
set
{
_name = value;
}
}
public event PropertyChangedEventHandler PropertyChanged = delegate { };
public Character(int id, string name)
{
Id = id;
Name = name;
}
public void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
MainWindow.xaml
<Window x:Class="SmashWiiUOverlayManager.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:SmashWiiUOverlayManager"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<StackPanel Grid.Column="0" Grid.Row="0">
<ComboBox
Name="Player1CharacterDropdown"
ItemsSource="{Binding CharacterList, Mode=TwoWay}"
SelectedItem="{Binding Player1SelectedCharacter, Mode=TwoWay}"
SelectedValuePath="Name"
DisplayMemberPath="Name"
Width="144">
</ComboBox>
</StackPanel>
<StackPanel Grid.Column="0" Grid.Row="1" HorizontalAlignment="Right">
<ComboBox
Name="Player2CharacterDropdown"
ItemsSource="{Binding CharacterList, Mode=TwoWay}"
SelectedItem="{Binding Player2SelectedCharacter, Mode=TwoWay}"
SelectedValuePath="Character"
DisplayMemberPath="Name"
Width="144">
</ComboBox>
</StackPanel>
</Grid>
</Window>
MainWindow.xaml.cs
public partial class MainWindow : Window, INotifyPropertyChanged
{
private ObservableCollection<Character> _characterList;
public ObservableCollection<Character> CharacterList
{
get
{
return _characterList;
}
set
{
_characterList = value;
}
}
private Character _player1SelectedCharacter;
public Character Player1SelectedCharacter
{
get
{
return _player1SelectedCharacter;
}
set
{
_player1SelectedCharacter = value;
}
}
private Character _player2SelectedCharacter;
public Character Player2SelectedCharacter
{
get
{
return _player2SelectedCharacter;
}
set
{
_player2SelectedCharacter = value;
}
}
public event PropertyChangedEventHandler PropertyChanged = delegate { };
public MainWindow()
{
this.DataContext = this;
InitializeComponent();
CharacterList = new ObservableCollection<Character>
{
new Character(0, "Mario"),
new Character(1, "Luigi"),
new Character(2, "Wario"),
};
}
public void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
This code currently leaves the comboboxes empty.
When I use:
Player1CharacterDropdown.ItemsSource = new ObservableCollection<Character>
{
new Character(0, "Mario", ".\\images\\mario.png"),
new Character(1, "Luigi", ".\\images\\luigi.png"),
new Character(2, "Wario", ".\\images\\wario.png"),
};
... the combox gets filled, but it's databound to the property, which is what I would like.
What am I missing here?

How to set dependency property of ItemsControl.ItemTemplate and handle its events

I have a main control (MainWindow.xaml) and an user control (ItemView.xaml). MainWindow contains an ItemsControl for all the ItemView-s and a simple button to add an item. All logic is (should be?) inside two corresponding viewmodels (MainWindowViewModel and ItemViewModel). Below is my code (made it as short as possible), but I have two problems with it:
When a new item is added it is correctly displayed but the exception is raised (Cannot create default converter to perform 'two-way' conversions between types 'WpfApplication1.ItemView' and 'WpfApplication1.ItemViewModel'.).
The OnDelete event handler in MainWindowViewModel is never raised? Edit: actually the ViewModel property inside BtnDeleteClick is null so yeah... of course.
Btw - I use Fody PropertyChanged.
MainWindow.xaml:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:wpfApplication1="clr-namespace:WpfApplication1"
Title="MainWindow" Height="350" Width="525"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition></RowDefinition>
</Grid.RowDefinitions>
<Button Grid.Row="0" Width="100" Height="35" Content="Add" HorizontalAlignment="Left" Margin="10" Click="BtnAddClick"></Button>
<Border Grid.Row="1" MinHeight="50">
<ItemsControl ItemsSource="{Binding ViewModel.Items}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<wpfApplication1:ItemView ViewModel="{Binding ., PresentationTraceSources.TraceLevel=High, Mode=TwoWay}"></wpfApplication1:ItemView>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Border>
</Grid>
</Window>
MainWindow.xaml.cs:
[ImplementPropertyChanged]
public partial class MainWindow
{
public MainWindowViewModel ViewModel { get; set; }
public MainWindow()
{
InitializeComponent();
ViewModel = new MainWindowViewModel();
}
private void BtnAddClick(object sender, RoutedEventArgs e)
{
ViewModel.Add();
}
}
MainWindowViewModel.cs:
[ImplementPropertyChanged]
public class MainWindowViewModel
{
public ObservableCollection<ItemViewModel> Items { get; set; }
public MainWindowViewModel()
{
Items = new ObservableCollection<ItemViewModel>();
}
public void Add()
{
var item = new ItemViewModel();
item.OnDelete += (sender, args) =>
{
Debug.WriteLine("-- WAITING FOR THIS TO HAPPEN --");
Items.Remove(item);
};
Items.Add(item);
}
}
ItemViewModel.xaml:
<UserControl x:Class="WpfApplication1.ItemView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<Grid>
<Button Width="100" Height="35" Content="Delete" Click="BtnDeleteClick"></Button>
</Grid>
</UserControl>
ItemView.xaml.cs:
[ImplementPropertyChanged]
public partial class ItemView
{
public static readonly DependencyProperty ViewModelProperty = DependencyProperty.Register
(
"ViewModel", typeof(ItemViewModel), typeof(ItemView), new UIPropertyMetadata(null)
);
public ItemViewModel ViewModel
{
get { return (ItemViewModel)GetValue(ViewModelProperty); }
set { SetValue(ViewModelProperty, value); }
}
public ItemView()
{
InitializeComponent();
}
private void BtnDeleteClick(object sender, RoutedEventArgs e)
{
ViewModel.Delete();
}
}
And ItemViewModel.cs:
[ImplementPropertyChanged]
public class ItemViewModel
{
public event EventHandler OnDelete;
public void Delete()
{
var handler = OnDelete;
if (handler != null)
{
handler(this, new EventArgs());
}
}
}

You should not set
DataContext="{Binding RelativeSource={RelativeSource Self}}"
in the XAML of your ItemView. It effectively breaks the ViewModel="{Binding .}" binding in MainWindow.xaml, because the DataContext is no longer an ItemsViewModel, but an ItemsView.
As a rule, you should never explicitly set the DataContext of a UserControl, because all "external" bindings would then require an explicit Source or RelativeSource value.
That said, you're doing all this way too complicated. Instead of having a button click handler in your ItemsView, you could simply have a view model with a delete command, and bind the Button's Command property to this command.
It may look like this:
public class ItemViewModel
{
public string Name { get; set; }
public ICommand Delete { get; set; }
}
public class MainViewModel
{
public MainViewModel()
{
Items = new ObservableCollection<ItemViewModel>();
}
public ObservableCollection<ItemViewModel> Items { get; private set; }
public void AddItem(string name)
{
Items.Add(new ItemViewModel
{
Name = name,
Delete = new DelegateCommand(p => Items.Remove(p as ItemViewModel))
});
}
}
and would be used like this:
<UserControl x:Class="WpfApplication1.ItemView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
<Button Content="Delete"
Command="{Binding Delete}"
CommandParameter="{Binding}"/>
</Grid>
</UserControl>

How to bind listview to custom item collection

How do I get my custom item collection to show up in my list view using WPF data bindings?
I have a tried to make a ViewModel and a custom collection that the ViewModel manipulates, in an attempt to get this collection to show up in a listview. I have a view model and a custom collection and a custom item class:
public class TranslationViewModel
{
public TranslationViewModel() { this.translatedItems = new TransListboxCollection(); }
public TransListboxCollection translatedItems { get; private set; }
public void addTranslatedItem(TransListboxItem message)
{
translatedItems.Add(message);
}
}
public class TransListboxCollection : BindingList<TransListboxItem>
{
public TransListboxCollection()
{
//initialize
}
}
public class TransListboxItem : INotifyPropertyChanged
{
private String _rawString;
private String _tString;
public String rawString
{
get { return _rawString; }
set { _rawString = value; NotifyPropertyChanged("rawString"); }
}
public String tString
{
get { return _tString; }
set { _tString = value; NotifyPropertyChanged("tString"); }
}
public TransListboxItem(String value)
{
this.tString = value;
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public override string ToString()
{
return this.tString;
}
}
I have a WPF element hosted in a windows form
public partial class wGlobal : UserControl
{
public TranslationViewModel tvm { get; set; }
public wGlobal()
{
InitializeComponent();
this.DataContext = tvm;
}
}
The XAML code for such
<UserControl
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:MHF_Transcoder_3" x:Class="MHF_Transcoder_3.wGlobal"
mc:Ignorable="d"
d:DesignWidth="1000" d:DesignHeight="150">
<Grid Width="1000" Height="150">
<ListView x:Name="listView1" ItemsSource="{Binding tvm}" HorizontalAlignment="Left" Width="1000" Height="150" VerticalAlignment="Top" Background="Black" Foreground="White" RenderTransformOrigin="0.5,0.5">
<DataTemplate>
<TextBlock Text="{Binding tString}" ToolTipService.ToolTip="{Binding rawString}" />
</DataTemplate>
</ListView>
</Grid>
and I have that element hosted in a windows form control
public partial class frmGlobal : Form
{
wGlobal xamlForm;
TranslationViewModel tvm;
public frmGlobal()
{
InitializeComponent();
tvm = new TranslationViewModel();
xamlForm = (wGlobal)elementHost1.Child;
xamlForm.tvm = tvm;
}
delegate void addMessageCallback(TransListboxItem message);
public void addMessage(TransListboxItem message) {
tvm.addTranslatedItem(message);
}
}
When I get the program up and launch everything, all my list view says is "System.Windows.DataTemplate". I've never really worked with WPF or data bindings before. I'm open to any and all advice and suggestions. Please help me get this setup and properly working.

Wrap Datatemplate with ItemTemplate
<ListView x:Name="listView1" ItemsSource="{Binding translatedItems}" HorizontalAlignment="Left" Width="1000" Height="150" VerticalAlignment="Top" Background="Black" Foreground="White" RenderTransformOrigin="0.5,0.5">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding tString}" ToolTipService.ToolTip="{Binding rawString}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Also as the tvm is the datacontext, you must bind to the collection "translatedItems"

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