Reputation: 85775
I must say that I really dislike the LongListSelector in WP8 and like the toolkit version so much better.
First it is not MVVM compatible so I found this code to make it so.
public class LongListSelector : Microsoft.Phone.Controls.LongListSelector
{
public LongListSelector()
{
SelectionChanged += LongListSelector_SelectionChanged;
}
void LongListSelector_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
SelectedItem = base.SelectedItem;
}
public static readonly DependencyProperty SelectedItemProperty =
DependencyProperty.Register(
"SelectedItem",
typeof(object),
typeof(LongListSelector),
new PropertyMetadata(null, OnSelectedItemChanged)
);
private static void OnSelectedItemChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var selector = (LongListSelector)d;
selector.SelectedItem = e.NewValue;
}
public new object SelectedItem
{
get { return GetValue(SelectedItemProperty); }
set { SetValue(SelectedItemProperty, value); }
}
}
then I made a view model using mvvm light
public class MainViewModel : ViewModelBase
{
public MainViewModel()
{
MyList = new ObservableCollection<Test>
{
new Test
{
Name = "test 1"
},
new Test
{
Name = "test 2"
}
};
ButtonCmd = new RelayCommand(() => Hit());
}
private void Hit()
{
SelectedItem = null;
}
public ObservableCollection<Test> MyList { get; set; }
/// <summary>
/// The <see cref="SelectedItem" /> property's name.
/// </summary>
public const string SelectedItemPropertyName = "SelectedItem";
private Test selectedItem = null;
/// <summary>
/// Sets and gets the SelectedItem property.
/// Changes to that property's value raise the PropertyChanged event.
/// </summary>
public Test SelectedItem
{
get
{
return selectedItem;
}
set
{
if (value != null)
{
MessageBox.Show(value.Name);
}
if (selectedItem == value)
{
return;
}
RaisePropertyChanging(() => SelectedItem);
selectedItem = value;
RaisePropertyChanged(() => SelectedItem);
}
}
public RelayCommand ButtonCmd
{
get;
private set;
}
then I made a model
public class Test : ObservableObject
{
public string Name { get; set; }
}
then I made the xaml
<phone:PhoneApplicationPage
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:ignore="http://www.ignore.com"
xmlns:local="clr-namespace:MvvmLight2" x:Class="MvvmLight2.MainPage"
mc:Ignorable="d ignore"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait"
Orientation="Portrait"
shell:SystemTray.IsVisible="True"
DataContext="{Binding Main, Source={StaticResource Locator}}">
<!--LayoutRoot is the root grid where all page content is placed-->
<Grid x:Name="LayoutRoot"
Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<local:LongListSelector ItemsSource="{Binding MyList}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}">
<local:LongListSelector.Resources>
<DataTemplate x:Key="ItemTemplate">
<Grid>
<TextBlock Text="{Binding Name}" HorizontalAlignment="Left" VerticalAlignment="Top" FontSize="48"/>
</Grid>
</DataTemplate>
</local:LongListSelector.Resources>
<local:LongListSelector.ItemTemplate>
<StaticResource ResourceKey="ItemTemplate"/>
</local:LongListSelector.ItemTemplate>
</local:LongListSelector>
<Button Content="Unselect" HorizontalAlignment="Left" Margin="142,81,0,0" Grid.Row="1" VerticalAlignment="Top" Command="{Binding ButtonCmd, Mode=OneWay}"/>
</Grid>
</phone:PhoneApplicationPage>
when I click on the first item in the list, the message box shows up, if I hit it again nothing happens. I then hit my button which nulls out the selectedItem(which in the old toolkit version would be enough) and try again and nothing happens.
Only way I can every select the first row is by selecting the second row which is really bad if say the list only has 1 item at any given time.
Weird thing is that a simple collection of strings does not even require me to set the SelectItem to null as it always seems to deselect but when it comes to complex types it is a no go.
Upvotes: 0
Views: 541
Reputation: 371
I've used the same code and ran into the very same problem. Reason for it is that your SelectedItem property overshadows the base.SelectedItem property. When setting it to a new value, not only set your SelectedItem property but the base one as well:
public new object SelectedItem
{
get { return GetValue(SelectedItemProperty); }
set
{
SetValue(SelectedItemProperty, value);
base.SelectedItem = value;
}
}
Then you have a MVVM capable code and can reset the SelectedItem in your ViewModel as well (by setting it to null).
Upvotes: 1
Reputation: 2617
you can easily achieve via in selectionchanged event
void LongListSelector_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if((sender as LongListSelector).SelectedItem == null){
return;
}
SelectedItem = base.SelectedItem;
(sender as LongListSelector).SelectedItem = null;
}
Upvotes: 0