WPF: bind my CheckBox into my commnd pure XAML - wpf

Question

I try to bind my CheckBox into my commnd.
Base view model
public ViewModelBase()
{
SelectedFileCommand = new SelectedFileCommand(this);
}
<Page.DataContext>
<viewmodel:ViewModelBase/>
</Page.DataContext>
Command
public class SelectedFileCommand : ICommand
{
public event EventHandler CanExecuteChanged;
public ViewModelBase ViewModel { get; set; }
public SelectedFileCommand(ViewModelBase viewModel)
{
ViewModel = viewModel;
}
public bool CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
}
}
}
My CheckBox
<CheckBox IsChecked="{Binding IsSelected}"
<i:Interaction.Triggers>
<i:EventTrigger EventName="Checked">
<i:InvokeCommandAction Command="{Binding SelectedFileCommand}" CommandParameter="{Binding}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</CheckBox>
I also Try:
<CheckBox DataContext="{Binding}"
<i:Interaction.Triggers>
<i:EventTrigger EventName="IsChecked">
<i:InvokeCommandAction Command="{Binding SelectedFileCommand}"
CommandParameter="CheckBox.IsChecked"/>
</i:EventTrigger>
</i:Interaction.Triggers>
But my Execute function not called.
EDIT
I forgot to mention that this CheckBox is inside ListViewItem
Working solution
<CheckBox IsChecked="{Binding IsSelected}"
Command="{Binding DataContext.CheckBoxSelectedFileCommand, ElementName=mainView}"
CommandParameter="{Binding IsChecked}"/>

Answer 1

If the checkbox is in a listview when you say Command="{Binding SelectedFileCommand}" you will bind to the listview item's datacontext. If yor command is in the viewmodel of your window this won't work. Something like this will bind to the command that is in your main viewmodel.
Command="{Binding DataContext.SelectedFileCommand, ElementName=mainView}"
Here I gave the window x:Name=mainView. This way I can bind to properties of it's dataContext.
And, IsChecked is not an event you should use "Checked".
Last, the command parameter issue. Since there are two different events for checkbox (Checked/Unchecked) you can use two commands and not pass any parameters. Or you can put a property in the list item viewmodel like;
public bool IsChecked { get; set; }
and you can bind your checkbox's IsChecked property to this property. And finally you can bind command parameter to this new property.
Edit: Full example
<Window x:Class="WpfApp2.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:i="http://schemas.microsoft.com/expression/2010/interactivity"
x:Name="mainView"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Grid>
<ListView ItemsSource="{Binding Items}">
<ListView.ItemTemplate>
<DataTemplate>
<CheckBox Content="{Binding Text}" IsChecked="{Binding IsChecked}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Checked">
<i:InvokeCommandAction Command="{Binding DataContext.SelectedFileCommand, ElementName=mainView}"
CommandParameter="{Binding IsChecked}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</CheckBox>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</Window>
Codebehind:
using System;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Input;
namespace WpfApp2
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.DataContext = new MainViewModel();
}
}
public class MainViewModel
{
public ObservableCollection<ItemViewModel> Items { get; set; } = new ObservableCollection<ItemViewModel>();
public ICommand SelectedFileCommand { get; set; }
public MainViewModel()
{
SelectedFileCommand = new SelectedFileCommand(this);
this.Items.Add(new ItemViewModel() { Text = "Item 1" });
this.Items.Add(new ItemViewModel() { Text = "Item 2" });
this.Items.Add(new ItemViewModel() { Text = "Item 3" });
this.Items.Add(new ItemViewModel() { Text = "Item 4" });
}
}
public class ItemViewModel
{
public string Text { get; set; }
public bool IsChecked { get; set; }
}
public class SelectedFileCommand : ICommand
{
public event EventHandler CanExecuteChanged;
public MainViewModel ViewModel { get; set; }
public SelectedFileCommand(MainViewModel viewModel)
{
ViewModel = viewModel;
}
public bool CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
var x = parameter;
}
}
}