I have a problem with MVVM-Light. I use the version 5.3.0.0...
.XAML
<DockPanel Dock="Top">
<Button Margin="5" VerticalAlignment="Top" HorizontalAlignment="Center" Command="{Binding CancelDownloadCommand}" FontSize="20"
Background="Transparent" BorderThickness="2" BorderBrush="{StaticResource AccentColorBrush4}" ToolTip="Cancelar"
DockPanel.Dock="Right">
<StackPanel Orientation="Horizontal">
<Image Source="Images/48x48/Error.png" Height="48" Width="48"/>
<Label Content="{Binding ToolTip, RelativeSource={RelativeSource AncestorType={x:Type Button}}}" FontFamily="Segoe UI Light"/>
</StackPanel>
</Button>
<Button Margin="5" VerticalAlignment="Top" HorizontalAlignment="Center" Command="{Binding DownloadCommand}" FontSize="20"
Background="Transparent" BorderThickness="2" BorderBrush="{StaticResource AccentColorBrush4}" ToolTip="Descargar"
DockPanel.Dock="Right">
<StackPanel Orientation="Horizontal">
<Image Source="Images/48x48/Download.png" Height="48" Width="48"/>
<Label Content="{Binding ToolTip, RelativeSource={RelativeSource AncestorType={x:Type Button}}}" FontFamily="Segoe UI Light"/>
</StackPanel>
</Button>
</DockPanel>
DownloadViewModel.cs
I used a MessageBox, but in my case, call a method that reads an XML. This example does not work, the buttons are disabled, but are not reactivated at the end of execution. I need to click on the UI to activate.
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.CommandWpf;
private async void Download()
{
Reset();
await Task.Run(() =>
{
MessageBox.Show("Hello");
});
Reset();
}
private void Reset()
{
IsEnabled = !IsEnabled;
IsEnabledCancel = !IsEnabledCancel;
}
private ICommand _downloadCommand;
public ICommand DownloadCommand
{
get { return _downloadCommand ?? (_downloadCommand = new RelayCommand(Download, () => IsEnabled)); }
}
private ICommand _cancelDownloadCommand;
public ICommand CancelDownloadCommand
{
get
{
return _cancelDownloadCommand ??
(_cancelDownloadCommand = new RelayCommand(CancelDownload, () => IsEnabledCancel));
}
}
private bool _isEnabled = true;
private bool IsEnabled
{
get { return _isEnabled; }
set
{
if (_isEnabled != value)
{
_isEnabled = value;
RaisePropertyChanged();
}
}
}
private bool _isEnabledCancel;
private bool IsEnabledCancel
{
get { return _isEnabledCancel; }
set
{
if (_isEnabledCancel != value)
{
_isEnabledCancel = value;
RaisePropertyChanged();
}
}
}
By using CommandManager.InvalidateRequerySuggested(), I fixed it. But read somewhere that is not recommended because this command checks all RelayCommand. This did not happen to me before.
But if within the Task.Run not add anything. It works perfectly. Buttons are activated and deactivated again.
private async void Download()
{
Reset();
await Task.Run(() =>
{
// WIDTHOUT CODE
// WIDTHOUT CODE
// WIDTHOUT CODE
});
Reset();
}
When you update CanExecute, in your case IsEnabled and IsEnabledCancel properties, you have to raise CanExecuteChanged event.
Even more you can little bit simplify your code.
private bool _isEnabled;
public bool IsEnabled
{
get { return _isEnabled; }
set
{
if (Set(ref _isEnabled, value))
{
DownloadCommand.RaiseCanExecuteChanged();
}
}
}
The same way update your IsEnabledCancel property.
Of course, you have to declare your command as RelayCommand and not ICommand.
private RelayCommand _downloadCommand;
public RelayCommand DownloadCommand
{
get { return _downloadCommand ?? (_downloadCommand = new RelayCommand(Download, () => IsEnabled)); }
}
You can also read about: "A smart MVVM command".
Looking at the source code for MVVM Light, it is based around the CommandManager.InvalidateRequerySuggested() (anti) pattern. Which you rightly say is a massive performance hog, due to the global nature of the (anti)pattern.
The problem lies in the constructor. public RelayCommand(Action execute, Func<bool> canExecute)
With the canExecute being a Func<bool>, it is impossible to be able to get (at runtime) the property name, and is therefore impossible to bind on the the INotifyPropertyChanged.PropertyChanged event. Thus causing the command to re-evaluate the canExecute.
#kubakista shows you how to force the re-evaluation by calling the RaiseCanExecuteChanged method. But that really breaks the single responsibility principle, and leaks the implementation of the ICommand.
My advice is to use ReactiveUI's ReactiveCommand. This allows you to do:
DownloadCommand = ReactiveCommand.Create(Download, this.WhenAnyValue(x => x.IsEnabled).Select(enabled => enabled));
CancelDownloadCommand = ReactiveCommand.Create(CancelDownload, this.WhenAnyValue(x => x.IsEnabled).Select(enabled => false == enabled));
public bool IsEnabled
{
get {return _isEnabled; }
set
{
_isEnabled = value;
OnPropertyChanged();
}
}
One thing i did notice is that your Enabled Properties (IsEnabled, IsEnabledCancel) are private when they should be public. However that doesn't fix your issue :)
A simple fix is to get rid of the CanExecute part of your Command
eg
public ICommand DownloadCommand
{
get { return _downloadCommand ?? (_downloadCommand = new RelayCommand(Download)); }
}
and bind to your property on the Button.IsEnabledproperty in xaml
eg
<Button IsEnabled="{Binding IsEnabled}" Margin="5" VerticalAlignment="Top"
HorizontalAlignment="Center" Command="{Binding DownloadCommand}"
FontSize="20" Background="Transparent" BorderThickness="2"
BorderBrush="Red" ToolTip="Descargar" DockPanel.Dock="Right">
...
</Button>
Hope that helps
Related
I have a ListBox control with TypeUsers.When I select some record in Listbox and update Name in TextBox the Name property/textbox return always null. Never take value from TextBox, always null ?
Image description here
This is my code
<ListBox x:Name="LstTypeUsers"
Grid.Row="0" Grid.Column="4"
Width="220" Height="120"
ScrollViewer.VerticalScrollBarVisibility="Visible"
ItemsSource="{Binding TypeUsers}"
DisplayMemberPath="Name">
</ListBox>
<TextBox
Grid.Row="0" Grid.Column="2"
x:Name="txtName"
HorizontalAlignment="Left" Height="23"
TextWrapping="Wrap"
VerticalAlignment="Top" Width="170"
Text="{Binding ElementName=LstTypeUsers, Path=SelectedItem.Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}"
Validation.ErrorTemplate="{x:Null}"/>
<Button
Grid.Column="0"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Width="100" Height="30"
Command="{Binding UpdateTypeUserCmd}"
Grid.ColumnSpan="3" Margin="20,90,0,0">
<StackPanel Orientation="Horizontal">
<Image Source="/Images/Save.png" />
<TextBlock Width="55" Height="18" ><Run Text=" "/><Run Text="Update"/></TextBlock>
</StackPanel>
</Button>
EDIT
// Model class
public class UserType: INotifyPropertyChanged
{
[Key]
private int usertypeId;
public int UserTypeId
{
get
{
return this.usertypeId;
}
set
{
this.usertypeId = value;
OnPropertyChanged("UserTypeId");
}
}
[MaxLength(200)]
private string name;
public string Name
{
get
{
return this.name;
}
set
{
this.name = value;
OnPropertyChanged("Name");
}
}
[Required]
private bool status;
public bool Status
{
get
{
return this.status;
}
set
{
this.status = value;
OnPropertyChanged("Status");
}
}
public virtual ObservableCollection<User> User { get; private set; }
public UserType()
{
this.User = new ObservableCollection<User>();
}
}
// ViewModelBase class
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
// UserTypeViewModel
public class UserTypeViewModel
private UserType _userType;
private ObservableCollection<UserType> _UserTypeList;
// Constructor
public UserTypeViewModel()
{
_userType = new UserType();
_UserTypeList = new ObservableCollection<UserType>(GetUserTypeAll());
}
public ObservableCollection<TypeUsers> TypeUsers
{
get
{
return _UserTypeList;
}
set
{
_UserTypeList = value;
//OnPropertyChanged("TypeUsers");
}
}
public string Name
{
get
{
return _userType.Name;
}
set
{
_userType.Name = value;
//OnPropertyChanged("Name");
}
}
Thank you.
Implement INotifyPropertyChanged interface in UserType class.
You're binding directly to the WPF control (ListBox) and not the ViewModel. I suggest you add a property in your ViewModel that will bind to the TextBox.Text property, once the data changes or the user had changed the value in the TextBox, then the data will update and be reflected in the UI.
Also, if I remember correctly, at launch, the SelectedItem property of the ListBox is null, so there might be a problem there too, but I'm not certain about that...
I have resolved my problem. I have also implemented INotifyPropertyChanged interface in Model class. I'm new in WPF MVVM and I read that this interface is implemented only in the ViewModel for connection with View. Now I have implemented in both classes and everything works great.
Thanks Everyone.
Please help, I was trying to do this small example.
My aim is to when I keep the checkbox ticked the app should show the the Ip address of the Host I enter. But The checkbox IsChecked property is never updated in the view model, Even it is been changed in the UI
My View `
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.Background>
<LinearGradientBrush>
<LinearGradientBrush.GradientStops>
<GradientStop Offset="0.00" Color="LavenderBlush" />
</LinearGradientBrush.GradientStops>
</LinearGradientBrush>
</Grid.Background>
<StackPanel Grid.Row="0" Margin="150,30,69,236" Grid.ColumnSpan="2">
<TextBox x:Name="inputBox" Text="{Binding TxtHostName, Mode=TwoWay}" Foreground="Azure" Background="YellowGreen" VerticalAlignment="Bottom" Height="45"/>
</StackPanel>
<Button Command="{Binding StartCommand }" Content="Get IP" HorizontalAlignment="Left" Margin="257,89,0,0" VerticalAlignment="Top" Width="75" RenderTransformOrigin="0.013,-0.273"/>
<TextBlock Text="{Binding IpAddress}" Background="BlueViolet" Margin="150,153,69,104" Grid.ColumnSpan="2" />
<Button Content="Close" Command="{Binding CloseCommand}" HorizontalAlignment="Left" Margin="257,250,0,0" VerticalAlignment="Top" Width="75"/>
<CheckBox Content="CheckBox" IsChecked="{Binding IsSelected, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" HorizontalAlignment="Left" Margin="150,111,0,0" VerticalAlignment="Top"/>
</Grid>
`
My ViewModel:
public class ViewModel:INotifyPropertyChanged
{
#region INPC
public void RaisePropertyChanged(string propName)
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
}
public event PropertyChangedEventHandler PropertyChanged;
#endregion
private string txtHostName;
public string TxtHostName
{
get { return txtHostName; }
set { txtHostName = value;
RaisePropertyChanged("TxtHostName");
}
}
private string ipAddress;
public string IpAddress
{
get { return ipAddress; }
set { ipAddress = value;
RaisePropertyChanged("IpAddress");
}
}
private bool checkbox;
public bool CheckBox
{
get { return checkbox; }
set { checkbox = value;
RaisePropertyChanged("IsSelected");
}
}
public event EventHandler RequestClose;
protected void OnRequestClose()
{
if (RequestClose != null)
RequestClose(this, EventArgs.Empty);
}
private RelayCommand _StartCommand;
public ICommand StartCommand
{
get
{
if (this._StartCommand == null)
this._StartCommand = new RelayCommand(StartClick);
return this._StartCommand;
}
}
private RelayCommand _CloseCommand;
public ICommand CloseCommand
{
get
{
if(this._CloseCommand==null)
this._CloseCommand=new RelayCommand(CloseClick);
return this._CloseCommand;
}
}
private void CloseClick(object obj)
{
OnRequestClose();
}
private void StartClick(object obj)
{
if (checkbox)
{
string HostName = TxtHostName;
IPAddress[] ipaddress = Dns.GetHostAddresses(HostName);
foreach (IPAddress ipaddr in ipaddress)
{
IpAddress = ipaddr.ToString();
}
}
else
{
IpAddress = "Please tick the checkbox";
}
}
}
}
The RealyCommand is as it should be.
The CheckBox Property value never changes weather I change it in the UI or not.
Your raising your property changed event against IsSelected, but your bindable property is called Checkbox, rename Checkbox to IsSelected and update your private variable to something like isSelected.
In this case Id rename the variable to IsChecked or ComboBoxIsChecked.
I'm not sure if there is a copy-and-paste error but your View Model property is called Checkbox while you are raising the property changed event using the label IsSelected.
This and the error in the binding might be your problem. Based on your View Model the binding should be:-
<CheckBox Content="CheckBox" IsChecked="{Binding Checkbox, Mode=TwoWay}" HorizontalAlignment="Left" Margin="150,111,0,0" VerticalAlignment="Top"/>
Update: Recommendation if you are using C# 5.0 or above
To avoid typo's when creating setters and raising IPropertyNotifyChange events I would recommend using the CallerMemberName attribute as follows:-
public void RaisePropertyChanged([CallerMemberName] string propName = "")
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
}
Then your setter in your example becomes:-
private bool checkbox;
public bool CheckBox
{
get { return checkbox; }
set { checkbox = value;
RaisePropertyChanged();
}
}
Meaning as you refactor your View Model then the compiler will insert the name of the calling property to ensure the label in the INotifyProertyChanged event matches your property name without you having to remember to manually update it yourself.
My WPF window binds directly to an Entity Framework data context (CollectionViewSource). Users begin editing immediately once a record is found. The moment the form is dirty I'd like to disable the Add button and enable the Save and Undo buttons. Is there a simple way to do this using binding or an event?
I'm not using MVVM. I use Entity Framework database first and the EF designer. I'm hoping to avoid adding code for every field. The database is quite large.
You can do this without events if you'd like. And you can leverage the power of DataBinding without going so far as MVVM. The example below demonstrates, in a very simple way, how you can accomplish this. If your entity classes don't already have an IsDirty property (it has been a while since I've used database-first EF), you could add the property with a partial class.
XAML:
<TextBlock HorizontalAlignment="Right" VerticalAlignment="Center" Text="Name:" Margin="10"/>
<TextBox x:Name="NameTextBox" Grid.Column="1" HorizontalAlignment="Stretch" VerticalAlignment="Center" Margin="10" Text="{Binding Name, UpdateSourceTrigger=PropertyChanged}"/>
<StackPanel Grid.Row="1" Grid.ColumnSpan="2" Orientation="Horizontal" HorizontalAlignment="Right">
<Button Content="Save" HorizontalAlignment="Right" Margin="5" IsEnabled="{Binding IsDirty}" />
<Button Content="Cancel" HorizontalAlignment="Right" Margin="5" IsEnabled="{Binding IsDirty}" Click="Cancel_Click"/>
<Button Content="Add" HorizontalAlignment="Right" Margin="5" IsEnabled="{Binding IsClean}"/>
</StackPanel>
</Grid>
</Window>
A test Entity class:
public class Entity : INotifyPropertyChanged
{
private string _name;
private bool _isDirty = false;
public string Name
{
get { return _name; }
set
{
if(!IsDirty)
IsDirty = (value != _name);
_name = value;
RaisePropertyChanged("Name");
}
}
public bool IsDirty
{
get{ return _isDirty; }
set{
_isDirty = value;
RaisePropertyChanged("IsDirty");
RaisePropertyChanged("IsClean");
}
}
public bool IsClean
{
get { return !_isDirty; }
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
And the code behind for the window:
namespace Test
{
public partial class EditTesting : Window
{
private Entity _myEntity;
public EditTesting()
{
InitializeComponent();
_myEntity = new Entity();
this.DataContext = _myEntity;
}
private void Cancel_Click(object sender, RoutedEventArgs e)
{
_myEntity.Name = string.Empty;
_myEntity.IsDirty = false;
}
}
}
Pressing the delete key is not causing the command below to fire. One can assume DelegateCommand follows interface contracts since other instances of DelegateCommand referenced in the View are properly firing within the ViewModel.
Why?
View:
<ListBox Height="132"
Name="lbFiles"
ItemsSource="{Binding LbItems, UpdateSourceTrigger=PropertyChanged,ValidatesOnDataErrors=True}"
VerticalAlignment="Center"
SelectedValue="{Binding Path=ListBoxSelection}">
<ListBox.InputBindings>
<KeyBinding Key="Delete"
Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}
,Path=DataContext.CommandInputFilesDeleteSelected}" />
</ListBox.InputBindings>
ViewModel:
private DelegateCommand commandInputFilesDeleteSelected;
public ICommand CommandInputFilesDeleteSelected {
get {
if (commandInputFilesDeleteSelected == null) {
commandInputFilesDeleteSelected = new DelegateCommand(InputFilesDeleteSelected);
}
return saveCommand;
}
}
private void InputFilesDeleteSelected() { //this never fires :(
LbItems.Remove(ListBoxSelection);
}
private DelegateCommand commandInputFilesDeleteSelected;
public ICommand CommandInputFilesDeleteSelected {
get {
if (commandInputFilesDeleteSelected == null) {
commandInputFilesDeleteSelected = new DelegateCommand(InputFilesDeleteSelected);
}
return saveCommand; //changed from saveCommand to commandInputFilesDeleteSelected whoops
}
}
I want to implement a checkbox which functions as a select-all / unselect-all checkbox but I am getting some problems with the binding. I am not really new to XAML and WPF so it is a mistery to me why my code is not working. I hope you can help. This is what I am doing:
First of all, I use MVVMLight and the event-to-command tags.
My view is called SetupView.xaml and my view-model is called SetupViewModel.cs
public class SetupViewModel : ViewModelBase
{
private List<FilterOptions> m_informationToShow;
private FilterOptions m_currentSelection;
public List<FilterOptions> InformationToShow
{
get { return m_informationToShow; }
set
{
m_informationToShow = value;
RaisePropertyChanged("InformationToShow");
RaisePropertyChanged("InformationToShowCount");
}
}
public FilterOptions CurrentSelection
{
get { return m_currentSelection; }
set
{
m_currentSelection = value;
RaisePropertyChanged("CurrentSelection");
}
}
}
The FilterOptions-object is my model object. Because you will need some of it it to understand the problem, here it show the part you need to understand the problem:
public class FilterOptions
{
private string m_projectName;
private BugsFilter m_bugsFilter;
private BuildsFilter m_buildsFilter;
private ChangeSetsFilter m_changeSetsFilter;
private ProgressInfoFilter m_progressInfoFilter;
private RisksFilter m_risksFilter;
private bool m_projectHealthFilter;
public bool AllFilterValues
{
get
{
if (m_bugsFilter.AtLeastOneFieldEnabled() ||
m_buildsFilter.AtLeastOneFieldEnabled() ||
m_changeSetsFilter.AtLeastOneFieldEnabled() ||
m_progressInfoFilter.AtLeastOneFieldEnabled() ||
m_risksFilter.AtLeastOneFieldEnabled() ||
m_projectHealthFilter
)
{
return true;
}
else
{
return false;
}
}
set
{
if (value == false)
{
m_bugsFilter.NoInformation();
m_buildsFilter.NoInformation();
m_changeSetsFilter.NoInformation();
m_progressInfoFilter.NoInformation();
m_risksFilter.NoInformation();
m_projectHealthFilter = false;
}
else
{
m_bugsFilter.CompleteInformation();
m_buildsFilter.CompleteInformation();
m_changeSetsFilter.CompleteInformation();
m_progressInfoFilter.CompleteInformation();
m_risksFilter.CompleteInformation();
m_projectHealthFilter = true;
}
}
}
I will proceed with my view:
<UserControl.Resources>
<viewModels:SetupViewModel x:Key="thisViewModel"></viewModels:SetupViewModel>
<DataTemplate x:Key="ProjectEntryTemplate">
<Border Margin="75,20,5,0">
<CheckBox Name="naam" Content="{Binding ProjectName}"
FontFamily="Segoe UI"
FontWeight="Light"
FontSize="24"
IsChecked="{Binding AllFilterValues}"
DataContext="{Binding}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Checked">
<mvvm:EventToCommand Command="{Binding ProjectListItemCheckedChanged, Source={StaticResource thisViewModel}}"
PassEventArgsToCommand="True"/>
</i:EventTrigger>
<i:EventTrigger EventName="Unchecked">
<mvvm:EventToCommand Command="{Binding ProjectListItemCheckedChanged, Source={StaticResource thisViewModel}}"
PassEventArgsToCommand="True"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</CheckBox>
</Border>
</DataTemplate>
</UserControl.Resources>
As you can see, I have a datatemplate which I am using in a listbox:
<ListBox ItemsSource="{Binding InformationToShow}"
ItemTemplate="{StaticResource ProjectEntryTemplate}"
SelectedIndex="0"
BorderThickness="0">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<mvvm:EventToCommand Command="{Binding SelectionListboxChanged}"
PassEventArgsToCommand="True"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</ListBox>
Besides from that, I have in the same window, in another grid on the right side, a lot of checkboxes. They all correspond to a given filter from the FilterOptions object. This is what I am doing in my view:
<StackPanel Orientation="Vertical"
Margin="0,5,0,5">
<CheckBox Name="activeBugs" Content="Active bugs"
FontFamily="Segoe UI"
FontWeight="Light"
FontSize="22"
IsChecked="{Binding CurrentSelection.BugsFilter.ActiveBugs}">
</CheckBox>
<CheckBox Name="resolvedBugs" Content="Resolved bugs"
FontFamily="Segoe UI"
FontWeight="Light"
FontSize="22"
IsChecked="{Binding CurrentSelection.BugsFilter.ResolvedBugs}"/>
<CheckBox Name="bugTrend" Content="Bug trend"
FontFamily="Segoe UI"
FontWeight="Light"
FontSize="22"
IsChecked="{Binding CurrentSelection.BugsFilter.BugTrend}"/>
</StackPanel>
Last but not least, this are the command functions which I have in my view-model:
RelayCommand m_selectionChanged;
public ICommand SelectionListboxChanged
{
get
{
if (m_selectionChanged == null)
m_selectionChanged = new RelayCommand(param => SelectionListboxChangedExec(param), param => true);
return m_selectionChanged;
}
}
private void SelectionListboxChangedExec(object param)
{
SelectionChangedEventArgs e = (SelectionChangedEventArgs)param;
ListBox b = (ListBox)e.Source;
CurrentSelection = (FilterOptions)b.SelectedItem;
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
RelayCommand m_projectCheckedChanged;
public ICommand ProjectListItemCheckedChanged
{
get
{
if (m_projectCheckedChanged == null)
m_projectCheckedChanged = new RelayCommand(param => ProjectListItemCheckedChangedExec(param), param => true);
return m_projectCheckedChanged;
}
}
private void ProjectListItemCheckedChangedExec(object param)
{
RoutedEventArgs e = (RoutedEventArgs)param;
CheckBox checkBox = (CheckBox)e.Source;
FilterOptions dataContext = (FilterOptions)checkBox.DataContext;
if ((bool)checkBox.IsChecked)
dataContext.AllFilterValues = true;
else
{
dataContext.AllFilterValues = false;
}
//var expression = checkBox.GetBindingExpression(ToggleButton.IsCheckedProperty);
//expression.UpdateSource();
}
I really cant find the problem. Is there anyone who can help me?
Your help will be much appreciated !!
Thank you all in advance !
Why do you have to do it with a command? bind the checkbox to a BindingOption class that internally notifies the parent ViewModel, this notification really doesn't belong in the view, but to the view-model.
The ViewModel isn't supposed to know that the view uses a CheckBox.
So what u should do have the individual options have a notifying IsSelected property bound to the CheckBoxes, provide each of them with a reference to the parent ViewModel, and notify the parent when current IsSelected was changed. Doing this in the View, although you can find many way to do it, you're not supposed to, MVVM is about separating view-tasks from viewmodel-tasks.
This is way also gives you control on "Select all", "Deselect all" or "Invert selection" etc.