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Problems with Data Binding Quickstart examples in WP7

开发者 https://www.devze.com 2023-04-11 23:27 出处:网络
As I was trying to learn Data Binding, I found one of the quick start examples not workin. Could you tell me if its wrong or have I gone wrong somewhere?

As I was trying to learn Data Binding, I found one of the quick start examples not workin. Could you tell me if its wrong or have I gone wrong somewhere?

http://create.msdn.com/en-US/education/quickstarts/Data_Binding_to_Controls#DisplayingItemsWithDataTemplate

The example uses CollectionView Source and ObservableCollection classes to dynamically bind the data to the UI elements. I have used a listpicker instead of a combo box. How ever I find that the the textblocks does not change as the selection in the list picker changes. Do I have to implement the INotifyProperty Changed? The following is my C# code

namespace binding3
{
public partial class MainPage : PhoneApplicationPage
{
public ObservableCollection<Recording> MyMusic = new ObservableCollection<Re开发者_C百科cording>();
// Constructor
public MainPage()
{
    InitializeComponent();
    MyMusic.Add(new Recording("Chris Sells", "Chris Sells Live", new DateTime(2008, 2, 5)));
    MyMusic.Add(new Recording("Luka Abrus", "The Road to Redmond", new DateTime(2007, 4, 3)));
    MyMusic.Add(new Recording("Jim Hance", "Best of Jim Hance", new DateTime(2007, 3, 6)));
    //listPicker1.DataContext = MyMusic;
    //RecordingDetails.DataContext = new CollectionViewSource { Source = MyMusic };
    LayoutRoot.DataContext = new CollectionViewSource { Source = MyMusic };
}

public class Recording 
{
    public Recording() { }
    public Recording(string artistName, string cdName, DateTime release)
    {
        Artist = artistName;
        Name = cdName;
        ReleaseDate = release;
    }

    public string Artist { get; set; }
    public string Name { get; set; }
    public DateTime ReleaseDate { get; set; }

    public override string ToString()
    {
        return Name + " by " + Artist + ", Released: " + ReleaseDate.ToShortDateString();
    }

}

and this is the xaml design

<!--ContentPanel - place additional content here-->
<StackPanel x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
    <toolkit:ListPicker Height="150" HorizontalAlignment="Left" Margin="5" x:Name="listPicker1"
                        VerticalAlignment="Top" Width="400" ItemsSource="{Binding}" FontSize="18">
        <toolkit:ListPicker.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal" Margin="2">
                    <TextBlock Text="Artist:" Margin="2"/>
                    <TextBlock Text="{Binding Artist}" Margin="2"/>
                    <TextBlock Text="CD:" Margin="10,2,0,2"/>
                    <TextBlock Text="{Binding Name}" Margin="2"/>
                </StackPanel>
            </DataTemplate>
        </toolkit:ListPicker.ItemTemplate>
    </toolkit:ListPicker>
    <StackPanel x:Name="RecordingDetails">
        <TextBlock Text="{Binding Artist}" Margin="5,0,0,0"/>
        <TextBlock Text="{Binding Name}" Margin="5,0,0,0"/>
        <TextBlock Text="{Binding ReleaseDate}" Margin="5,0,0,0"/>
    </StackPanel>
</StackPanel>

Thank You,

Alfah


The code works when you modify the xaml like this

<StackPanel x:Name="RecordingDetails">
            <TextBlock Text="{Binding SelectedItem.Artist, ElementName= listPicker1}" Margin="5,0,0,0"/>
            <TextBlock Text="{Binding SelectedItem.Name, ElementName= listPicker1}" Margin="5,0,0,0"/>
            <TextBlock Text="{Binding SelectedItem.ReleaseDate,ElementName= listPicker1}" Margin="5,0,0,0"/>
 </StackPanel>

You need to bind the selected item of the listpicker to the textblock so that the textblock is updated as the selection is changed. Dont know if there is a better way to do it. This solves the problem anyway.

Alfah

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