How to notify viewmodel collection that property on model class has changed - wpf

Question

I have a class that has a boolean property called IsChecked.
A collection of this class exist in my viewmodel. I've bound a datagrid in my view to this collection. I need to call a method in my viewmodel when the checkbox in the view gets changed. I've implemented INotifyPropertyChanged on the class and it is firing when I check the box but I don't know how to call the method in my viewmodel.
Here's the class in my model...
public class AccountComponent : INotifyPropertyChanged
{
public string Name { get; set; }
public decimal Amount { get; set; }
private bool _isChecked;
public bool IsChecked
{
get { return _isChecked; }
set
{
_isChecked = value;
NotifyPropertyChanged("IsChecked");
}
}
public bool Enabled { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
Here's the collection in my viewmodel...
private ObservableCollection<AccountComponent> _accountComponents;
private string _accountStatus;
public ObservableCollection<AccountComponent> AccountComponents
{
get { return _accountComponents; }
set
{
_accountComponents = value;
NotifyPropertyChanged("AccountComponents");
CalculateComponentTotal();
}
}
Here's my XAML in the view...
<DataGrid ItemsSource="{Binding AccountComponents}" AutoGenerateColumns="False" Margin="5">
<DataGrid.Columns>
<DataGridTemplateColumn>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Grid>
<CheckBox IsChecked="{Binding IsChecked, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" IsEnabled="{Binding Enabled}"/>
</Grid>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Binding="{Binding Name}" Header="Component" Width="*" IsReadOnly="True" ElementStyle="{DynamicResource TextBlock-Sketch}"/>
<DataGridTextColumn Binding="{Binding Amount,StringFormat={}{0:C}}" IsReadOnly="True" Header="Charge" ElementStyle="{DynamicResource TextBlock-Sketch}">
<DataGridTextColumn.CellStyle>
<Style>
<Setter Property="TextBlock.TextAlignment" Value="Right"/>
</Style>
</DataGridTextColumn.CellStyle>
</DataGridTextColumn>
</DataGrid.Columns>
</DataGrid>

Answer 1

Since AccountComponent implements INPC you can observe the IsChecked property in your VM.
say in your VM constructor:
AccountComponents = new ObservableCollection<AccountComponent>();
AccountComponents.CollectionChanged += AccountComponentsOnCollectionChanged;
...
private void AccountComponentsOnCollectionChanged(object sender, NotifyCollectionChangedEventArgs args) {
if (args.NewItems != null && args.NewItems.Count != 0)
foreach (AccountComponent account in args.NewItems)
account.PropertyChanged += AccountOnPropertyChanged;
if (args.OldItems != null && args.OldItems.Count != 0)
foreach (AccountComponent account in args.OldItems)
account.PropertyChanged -= AccountOnPropertyChanged;
}
private void AccountOnPropertyChanged(object sender, PropertyChangedEventArgs args) {
if (args.PropertyName == "IsChecked")
// Invoke Your VM Function Here
}
That should be it.

Answer 2

In Xaml:
add the following namspace..
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
Now for you checkbox add the following code:
<CheckBox>
<i:Interaction.Triggers>
<i:EventTrigger EventName="Checked">
<i:InvokeCommandAction Command="{Binding CheckedCommand}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</CheckBox>
In ViewModel:
public ICommand CheckedCommand
{
get
{
return new DelegateCommand(OnChecked);//Delegate command is the Implemntation of Icommand Interface
}
}
public void OnLogin(object param)
{
//code for you checked event
}
Hope this will help you.