Binding a TextBlock to a Property a ListView changes

Binding a TextBlock to a Property a ListView changes - c#

I just can't figure it out. What I am missing to bound the Textblock?
I need the TextBlock to update everytime I select a new item in the ListView.
This is a sample I made. I my real application, I used the id from the ListView1 to fetch something from my DB that I want to display in my textBlock..
I know WPF binds to Properties and I need to implement INotifyPropertyChanged but I can't get the bindings right or maybe I am missing something else?
I have added DateTime.Now.TosString() just to see more clearly if the TextBlock changes.
XAML:
<Window x:Class="WpfSO.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">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="30"/>
<RowDefinition />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition />
</Grid.ColumnDefinitions>
<TextBlock Grid.Row="0" x:Name="txtBlockPerson"
Text="{Binding MyPerson}" />
<ListView Grid.Row="1" Grid.Column="0" x:Name="ListView1"
ItemsSource="{Binding ListData}"
IsSynchronizedWithCurrentItem="True"
SelectionChanged="ListView1_SelectionChanged">
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="HorizontalContentAlignment" Value="Left" />
</Style>
</ListView.ItemContainerStyle>
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}"></TextBlock>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</Window>
C#
using System;
using System.ComponentModel;
using System.Windows;
using System.Collections.ObjectModel;
namespace WpfSO
{
public partial class MainWindow : Window
{
private ObservableCollection<Person> ListData { get; set; }
private const string _myName = "You clicked on: ";
public Person MyPerson { get; set; }
public MainWindow()
{
InitializeComponent();
// TextBlock
MyPerson = new Person(_myName);
txtBlockPerson.DataContext = MyPerson;
// ListView
ListData = new ObservableCollection<Person>();
var p1 = new Person("p1");
var p2 = new Person("p2");
ListData.Add(p1);
ListData.Add(p2);
ListView1.ItemsSource = ListData;
}
private void ListView1_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
{
MyPerson.Name = _myName + ListView1.SelectedItem + ". Time: " +DateTime.Now.ToString();
}
}
public class Person : INotifyPropertyChanged
{
private string _name;
public event PropertyChangedEventHandler PropertyChanged;
public string Name
{
get { return _name; }
set
{
if (value != _name)
{
_name = value;
OnPropertyChanged("PersonName");
}
}
}
public Person(string name)
{
Name = name;
}
// Create the OnPropertyChanged method to raise the event
protected void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
}
}

The OnPropertyChanged needs to have the correct name of your property..
Instead of OnPropertyChanged("PersonName"); use
OnPropertyChanged("Name");

Related

WPF Inculding a UserControl in another UserControl with multiple bindings on DependencyProperty [duplicate]

I wrote a customcontrol. It is a textbox with a button which opens a OpenFileDialog.
The Text property of the TextBox is bound to my dependency property "FileName". And if the user selects a file via the OpenFileDialog, i set the result to this property.
The TextBox gets the right value through binding.
But now my problem. For my view I'm using a ViewModel. So I have a Binding to my DependencyProperty "FileName" to the property in my ViewModel.
After changing the "FileName" property (changes direct to the textbox or selecting a file via the dialog), the viewmodel property doesn't update.
CustomControl.xaml.cs
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using Microsoft.Win32;
namespace WpfApplication1.CustomControl
{
/// <summary>
/// Interaction logic for FileSelectorTextBox.xaml
/// </summary>
public partial class FileSelectorTextBox
: UserControl, INotifyPropertyChanged
{
public FileSelectorTextBox()
{
InitializeComponent();
DataContext = this;
}
#region FileName dependency property
public static readonly DependencyProperty FileNameProperty = DependencyProperty.Register(
"FileName",
typeof(string),
typeof(FileSelectorTextBox),
new FrameworkPropertyMetadata(string.Empty,
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
new PropertyChangedCallback(OnFileNamePropertyChanged),
new CoerceValueCallback(OnCoerceFileNameProperty)));
public string FileName
{
get { return (string)GetValue(FileNameProperty); }
set { /*SetValue(FileNameProperty, value);*/ CoerceFileName(value); }
}
private bool _shouldCoerceFileName;
private string _coercedFileName;
private object _lastBaseValueFromCoercionCallback;
private object _lastOldValueFromPropertyChangedCallback;
private object _lastNewValueFromPropertyChangedCallback;
private object _fileNameLocalValue;
private ValueSource _fileNameValueSource;
private static void OnFileNamePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (d is FileSelectorTextBox)
{
(d as FileSelectorTextBox).OnFileNamePropertyChanged(e);
}
}
private void OnFileNamePropertyChanged(DependencyPropertyChangedEventArgs e)
{
LastNewValueFromPropertyChangedCallback = e.NewValue;
LastOldValueFromPropertyChangedCallback = e.OldValue;
FileNameValueSource = DependencyPropertyHelper.GetValueSource(this, FileNameProperty);
FileNameLocalValue = this.ReadLocalValue(FileNameProperty);
}
private static object OnCoerceFileNameProperty(DependencyObject d, object baseValue)
{
if (d is FileSelectorTextBox)
{
return (d as FileSelectorTextBox).OnCoerceFileNameProperty(baseValue);
}
else
{
return baseValue;
}
}
private object OnCoerceFileNameProperty(object baseValue)
{
LastBaseValueFromCoercionCallback = baseValue;
return _shouldCoerceFileName ? _coercedFileName : baseValue;
}
internal void CoerceFileName(string fileName)
{
_shouldCoerceFileName = true;
_coercedFileName = fileName;
CoerceValue(FileNameProperty);
_shouldCoerceFileName = false;
}
#endregion FileName dependency property
#region Public Properties
public ValueSource FileNameValueSource
{
get { return _fileNameValueSource; }
private set
{
_fileNameValueSource = value;
OnPropertyChanged("FileNameValueSource");
}
}
public object FileNameLocalValue
{
get { return _fileNameLocalValue; }
set
{
_fileNameLocalValue = value;
OnPropertyChanged("FileNameLocalValue");
}
}
public object LastBaseValueFromCoercionCallback
{
get { return _lastBaseValueFromCoercionCallback; }
set
{
_lastBaseValueFromCoercionCallback = value;
OnPropertyChanged("LastBaseValueFromCoercionCallback");
}
}
public object LastNewValueFromPropertyChangedCallback
{
get { return _lastNewValueFromPropertyChangedCallback; }
set
{
_lastNewValueFromPropertyChangedCallback = value;
OnPropertyChanged("LastNewValueFromPropertyChangedCallback");
}
}
public object LastOldValueFromPropertyChangedCallback
{
get { return _lastOldValueFromPropertyChangedCallback; }
set
{
_lastOldValueFromPropertyChangedCallback = value;
OnPropertyChanged("LastOldValueFromPropertyChangedCallback");
}
}
#endregion FileName dependency property
private void btnBrowse_Click(object sender, RoutedEventArgs e)
{
FileDialog dlg = null;
dlg = new OpenFileDialog();
bool? result = dlg.ShowDialog();
if (result == true)
{
FileName = dlg.FileName;
}
txtFileName.Focus();
}
#region INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion INotifyPropertyChanged
}
}
CustomControl.xaml
<UserControl x:Class="WpfApplication1.CustomControl.FileSelectorTextBox"
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="23" d:DesignWidth="300">
<Border BorderBrush="#FF919191"
BorderThickness="0">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" MinWidth="80" />
<ColumnDefinition Width="30" />
</Grid.ColumnDefinitions>
<TextBox Name="txtFileName"
HorizontalAlignment="Stretch"
VerticalAlignment="Center"
Grid.Column="0"
Text="{Binding FileName}" />
<Button Name="btnBrowse"
Click="btnBrowse_Click"
HorizontalContentAlignment="Center"
ToolTip="Datei auswählen"
Margin="1,0,0,0"
Width="29"
Padding="1"
Grid.Column="1">
<Image Source="../Resources/viewmag.png"
Width="15"
Height="15" />
</Button>
</Grid>
</Border>
</UserControl>
Using in a view:
<Window x:Class="WpfApplication1.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:WpfApplication1.ViewModels"
xmlns:controls="clr-namespace:WpfApplication1.CustomControl"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<vm:MainViewModel />
</Window.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="10" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<DataGrid ItemsSource="{Binding Files}" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTemplateColumn Header="File name" Width="*">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<controls:FileSelectorTextBox FileName="{Binding .}" Height="30" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
<ListBox ItemsSource="{Binding Files}" Grid.Row="2">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Window>
And the ViewModel:
using System.Collections.ObjectModel;
using System.ComponentModel;
namespace WpfApplication1.ViewModels
{
internal class MainViewModel
: INotifyPropertyChanged
{
public MainViewModel()
{
Files = new ObservableCollection<string> { "test1.txt", "test2.txt", "test3.txt", "test4.txt" };
}
#region Properties
private ObservableCollection<string> _files;
public ObservableCollection<string> Files
{
get { return _files; }
set
{
_files = value;
OnPropertyChanged("Files");
}
}
#endregion Properties
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion INotifyPropertyChanged Members
}
}
Is there any wrong using of the dependency property?
Note: The problem only occurs in DataGrid.

You need to set binding Mode to TwoWay, because by default binding works one way, i.e. loading changes from the view model, but not updating it back.
<controls:FileSelectorTextBox FileName="{Binding FileName, Mode=TwoWay}" Height="30" />
Another option is to declare your custom dependency property with BindsTwoWayByDefault flag, like this:
public static readonly DependencyProperty FileNameProperty =
DependencyProperty.Register("FileName",
typeof(string),
typeof(FileSelectorTextBox),
new FrameworkPropertyMetadata(default(string), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
Also when you change your custom dependency property from inside your control use SetCurrentValue method instead of directly assigning the value using property setter. Because if you assign it directly you will break the binding.
So, instead of:
FileName = dlg.FileName;
Do like this:
SetCurrentValue(FileNameProperty, dlg.FileName);

Change as following:
<TextBox Name="txtFileName"
HorizontalAlignment="Stretch"
VerticalAlignment="Center"
Grid.Column="0"
Text="{Binding FileName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />

Show List in xaml using ViewModel

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}}

How to select first item after filtering ICollectionView

I'm binding a ListView to an ICollectionView in my viewmodel. The ICollectionView has some predefined filters that are applied when you click some buttons. However I cannot seem to find any way to (auto) select the first item in the ListView after the collection has been filtered.
I've tried to set SelectedIndex=0, add both Target and Source notification to the binding, but all are ineffective when the filter applies.
Any pointers on how to achieve this?
EDIT: Below code illustrates my issue I'd say.
XAML:
<Window x:Class="CollectionViewTest.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:CollectionViewTest"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<local:MainViewModel/>
</Window.DataContext>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<!-- MENU -->
<StackPanel Orientation="Vertical">
<Button Content="Numbers below 4" Click="Below4_Click" Width="100"/>
<Button Content="Numbers below 7" Click="Below7_Click" Width="100"/>
<Button Content="All numbers" Click="All_Click" Width="100"/>
</StackPanel>
<!-- LIST -->
<ListView
Grid.Column="1"
SelectedIndex="0"
ItemsSource="{Binding Numbers, Mode=OneWay}"
SelectedItem="{Binding SelectedNumber, Mode=TwoWay}">
<ListView.Resources>
<DataTemplate DataType="{x:Type local:Number}">
<TextBlock Text="{Binding Value}" />
</DataTemplate>
</ListView.Resources>
</ListView>
<!-- DETAILS -->
<TextBlock Grid.Column="2" Text="{Binding SelectedNumber.Text}" Width="100"/>
</Grid>
</Window>
Code-Behind:
using System.Windows;
namespace CollectionViewTest
{
public partial class MainWindow : Window
{
private MainViewModel vm;
public MainWindow()
{
InitializeComponent();
vm = (MainViewModel)DataContext;
}
private void Below4_Click(object sender, RoutedEventArgs e)
{
vm.MenuFilter = f => f.Value < 4;
}
private void Below7_Click(object sender, RoutedEventArgs e)
{
vm.MenuFilter = f => f.Value < 7;
}
private void All_Click(object sender, RoutedEventArgs e)
{
vm.MenuFilter = f => true;
}
}
}
ViewModel:
using System;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows.Data;
using System.Collections.ObjectModel;
namespace CollectionViewTest
{
public class MainViewModel : PropertyChangedBase
{
public MainViewModel()
{
Numbers = new ObservableCollection<Number>();
NumberCollection = CollectionViewSource.GetDefaultView(Numbers);
NumberCollection.Filter = Filter;
NumberCollection.SortDescriptions.Add(new SortDescription("Value", ListSortDirection.Ascending));
for (int i = 0; i < 10; i++)
Numbers.Add(new Number { Value = i, Text = $"This is number {i}." });
}
private Func<Number, bool> menuFilter;
public Func<Number, bool> MenuFilter
{
get => menuFilter;
set
{
menuFilter = value;
NumberCollection.Refresh();
}
}
private bool Filter(object item)
{
var number = (Number)item;
return MenuFilter == null ? true : MenuFilter(number);
}
public ObservableCollection<Number> Numbers { get; set; }
public ICollectionView NumberCollection { get; set; }
private Number selectedNumber;
public Number SelectedNumber { get => selectedNumber; set => Set(ref selectedNumber, value); }
}
public class Number : PropertyChangedBase
{
public int Value { get; set; }
private string text;
public string Text { get => text; set => Set(ref text, value); }
}
public class PropertyChangedBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void Set<T>(ref T field, T newValue = default(T), [CallerMemberName] string propertyName = null)
{
field = newValue;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
As you can see, pressing one of the buttons changes the Filter and calls Refresh on the collection. What I would like to have, is that the first item in the list (here '0') is selected automatically which then would display the text "This is number 0" in the text in column 2.
I have tried both the SelectedIndex=0 and also MoveCurrentToFirst but nothing is selected.

Don't set SelectedIndex when binding to an ICollectionView. Instead, set its CurrentItem via MoveCurrentTo() or MoveCurrentToFirst():
myCollectionView.MoveCurrentTo(someItem);
...
myCollectionView.MoveCurrentToFirst();
Also, set IsSynchronizedWithCurrentItem on your ListView:
<ListView IsSynchronizedWithCurrentItem="True" ...
Detect when filter is applied
When the filter is evaluated, the collection view is refreshed which in turn resets the collection. To detect this, listen for the CollectionChanged event and look for the NotifyCollectionChangedAction.Reset flag. Please refer to the CollectionView source code for more details.

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?

Exception Occurring Infinitely in Content Control

First, this is a simplified version from a wizard control using MVVM. The problem is just easier to reproduce as described below
After much narrowing down, I have resolved an infinite exception in my code to be due to the WPF ContentControl. However, I have yet to figure out how to handle it, other than try-catch wrapping all of my possible instantiation code. Here is sample code that reproduces this...any help on how to keep this infinite exception from occurring would be greatly appreciated.
Additional Details
To sum up, the problem is that if the content control changes its contents, and the thing being loaded in throws an exception, then it will throw, then retry the load, causing the throw again and again.
MainWindow.xaml
<Window x:Class="WpfApplication8.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" Name ="Main">
<Grid>
<ContentControl Name="bar" Content="{Binding ElementName=Main, Path=foo}"/>
<Button Click="ButtonBase_OnClick" Margin="20" Width="50"/>
</Grid>
</Window>
MainWindow.xaml.cs
public partial class MainWindow : Window, INotifyPropertyChanged
{
private UserControl _foo;
public UserControl foo
{
get { return _foo; }
set { _foo = value; OnPropertyChanged("foo"); }
}
public MainWindow()
{
InitializeComponent();
foo = new UserControl1();
}
private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
foo = new UserControl2();
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
UserControl1 is blank and all default
UserControl2.xaml.cs
public UserControl2()
{
InitializeComponent();
throw new Exception();
}

Do not bind ContentControl to MainWindow. Instead use DataTemplates to select the content for the MainWindow. One example-contrived way of doing it is to bind the ContentControl's Content to the DataContext of the MainWindow.
First some observable test data is needed. The specifics of this data are not important. The main point is to have two different classes of test data from which to choose - TestData.cs:
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
namespace fwWpfDataTemplate
{
// Classes to fill TestData
public abstract class Person : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
string _name;
public string Name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("Name");
}
}
}
public class Student : Person { }
public class Employee : Person
{
float _salary;
public float Salary
{
get { return _salary; }
set
{
_salary = value;
OnPropertyChanged("Salary");
}
}
}
public class TestData : ObservableCollection<Person>
{
public TestData()
: base(new List<Person>()
{
new Student { Name = "Arnold" },
new Employee { Name = "Don", Salary = 100000.0f }
}) { }
}
}
Then add DataTemplates to MainWindow's resources - MainWindow.xaml:
<Window x:Class="fwWpfDataTemplate.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:me="clr-namespace:fwWpfDataTemplate"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<DataTemplate DataType="{x:Type me:Student}">
<StackPanel>
<TextBlock Text="Student"/>
<TextBlock Text="{Binding Name}"/>
</StackPanel>
</DataTemplate>
<DataTemplate DataType="{x:Type me:Employee}">
<StackPanel>
<TextBlock Text="Employee"/>
<TextBlock Text="{Binding Name}"/>
<TextBlock Text="Salary"/>
<TextBlock Text="{Binding Salary}"/>
</StackPanel>
</DataTemplate>
</Window.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<Button Content="Change Data Context" Click="Button_Click" />
<ContentControl Grid.Row="1" Content="{Binding}"/>
</Grid>
</Window>
Note: instead of the StackPanels the contents of the DataTemplates could be UserControl1, UserControl2, etc.
Then add some code to change the data context - MainWindow.cs:
using System.Windows;
namespace fwWpfDataTemplate
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
TestData testData = new TestData();
int testIndex = -1;
private void Button_Click(object sender, RoutedEventArgs e)
{
testIndex = (testIndex + 1) % testData.Count;
this.DataContext = testData[testIndex];
}
}
}
Enjoy.

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

Binding a TextBlock to a Property a ListView changes - c#

The OnPropertyChanged needs to have the correct name of your property.. Instead of OnPropertyChanged("PersonName"); use OnPropertyChanged("Name");

Related

WPF Inculding a UserControl in another UserControl with multiple bindings on DependencyProperty [duplicate]

Show List in xaml using ViewModel

How to select first item after filtering ICollectionView

C# WPF - ComboBox of databound ObservableCollection of classes

Exception Occurring Infinitely in Content Control

Categories

Resources