I'm new to UWP I am attempting to bind to an event in my ViewModel from a button flyout inside a listview that is shown on every item. I've looked at many solutions online and came up with the following code, it compiles fine but when I click the said Edit button nothing happens.
My ViewModel is available from the Page's context and not the Item's context
XAML
<ListView x:Name="MainListView"
ItemsSource="{x:Bind ViewModel.Devices, Mode=OneWay}"
SelectionMode="Multiple"
SelectionChanged="MainListView_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Width="Auto">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="0*"></ColumnDefinition>
<ColumnDefinition Width=".4*"></ColumnDefinition>
<ColumnDefinition Width="3*"></ColumnDefinition>
<ColumnDefinition Width="3*"></ColumnDefinition>
<ColumnDefinition Width="3*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="2" Text="{Binding AssetNumber}"/>
<TextBlock Grid.Column="3" Text="{Binding SerialNumber}"/>
<TextBlock Grid.Column="4" Text="{Binding Model}"/>
<Button Grid.Column="1" Height="30" Width="30">
<Button.Flyout>
<MenuFlyout>
<MenuFlyoutItem Text="Edit" Icon="Edit"
Command="{Binding ElementName=MainListView,Path=DataContext.ViewModel.EditCommand}"
CommandParameter="{Binding}"/>
</MenuFlyout>
</Button.Flyout>
</Button>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
View Model Class
public class MainPageViewModel
{
// Elements contained in the main listview
public ObservableCollection<Device> Devices = new ObservableCollection<Device>();
public MainPageViewModel()
{
DeviceProvider.Fill(ref Devices, 100);
EditCommand = new RelayCommand<Device>(EditDevice);
}
public RelayCommand<Device> EditCommand { get; set; }
private async void EditDevice(Device device)
{
// Code here that creates a dialog
}
}
The Device class
public class Device : INotifyPropertyChanged
{
private string assetNumber;
private string serialNumber;
private string model;
public string AssetNumber
{
get
{
return assetNumber;
}
set
{
assetNumber = value;
OnPropertyChanged();
}
}
public string SerialNumber
{
get
{
return serialNumber;
}
set
{
serialNumber = value;
OnPropertyChanged();
}
}
public string Model
{
get
{
return model;
}
set
{
model = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string name = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
}
The RelayCommand class
public class RelayCommand<T> : ICommand
{
private readonly Action<T> _execute;
private readonly Func<bool> _canExecute;
public event EventHandler CanExecuteChanged;
public RelayCommand(Action<T> execute) : this(execute, null)
{
}
public RelayCommand(Action<T> execute, Func<bool> canExecute)
{
if (execute == null)
throw new ArgumentNullException("execute");
_execute = execute;
_canExecute = canExecute;
}
public bool CanExecute(object parameter)
{
return _canExecute == null ? true : _canExecute();
}
public void Execute(object parameter)
{
_execute((T)parameter);
}
public void RaiseCanExecuteChanged()
{
var handler = CanExecuteChanged;
if (handler != null)
{
handler(this, EventArgs.Empty);
}
}
}
Your code doesn't seem to have any problems. So it should work perfectly. But if not, I'd suspect MainPage.ViewModel member might not be defined properly. The property to be used in {Binding} must be "public" and must have "get" accessor.
public sealed partial class MainPage : Page
{
public MainPageViewModel ViewModel { get; set; } = new MainPageViewModel();
public MainPage()
{
this.InitializeComponent();
DataContext = this;
}
}
So indeed I had forgotten to set the DataContext of MainPage it now works thanks