Windows Phone 7: ListBox SelectionChanged event

Question

I'm new to XAML and Windows Phone 7 SDK. I'm developing an Windows Phone 7 application and I don't know how to detect selected item from the ListBox. I'm using panorama template, here is my code:

<controls:PanoramaItem Header="Basic">
   <ListBox Margin="0,0,-12,0" Name="MyListBox" SelectionChanged="Elementary_SelectionChanged">
      <ListBox.ItemTemplate>
         <DataTemplate>
            <StackPanel Orientation="Horizontal" Margin="0,0,0,17">
               <Image Height="100" Width="100" Source="{Binding LevelPassedImage}" Margin="12,0,9,0"/>
               <StackPanel Width="311">
                  <TextBlock Name="lvlName" x:Uid="Elementary{Binding LevelId}" Text="{Binding LevelName}" TextWrapping="Wrap" Style="{StaticResource PhoneTextExtraLargeStyle}" />
                  <TextBlock Text="{Binding LevelPassed}" TextWrapping="Wrap" Margin="12,-6,12,0" Style="{StaticResource PhoneTextSubtleStyle}" />
               </StackPanel>
            </StackPanel>
         </DataTemplate>
      </ListBox.ItemTemplate>
   </ListBox>
</controls:PanoramaItem>

And C# code:

MessageBox.Show(Elementary.SelectedItem.ToString()); //returns "LocalXmlParsing.XMLParser"

I'm using XMLParser, app initialization code:

var parser = LocalXmlParsing.XMLParser.Instance;

StreamResourceInfo strm = Application.GetResourceStream(new Uri("Levels/ElementaryLevels.xml", UriKind.Relative));
StreamReader reader = new StreamReader(strm.Stream);
string data = reader.ReadToEnd();
parser.DataToParse = data;
parser.ParseStateData();
MyListBox.ItemsSource = parser.LevelCollection;

When I'm trying to detect SelectedItem, ListBox returns me this string: "LocalXmlParsing.XMLParser".

What is the ItemsSource of your ListBox? You must cast it to the type of the object. For example, if the soure is List, then you msut cast SelectItem to myClass. — Farhad Jabiyev, Aug 09 '13 at 18:00

Joe Brunscheon · Answer 1 · 2013-08-09T18:02:01.710

1

Your selected item is not a ListBoxItem, but it's actually the type of whatever object you bound to the ListBox through the ItemSource. So casting it to a ListBoxItem is returning you a null object.

ListBox.ItemsSource = new List<myObject>() { new myObject(), new myObject() };
ListBox.SelectedIndex = 1;
var selectedObject = ListBox.SelectedItem as myObject;

edited Aug 09 '13 at 18:02

answered Aug 09 '13 at 17:50

Joe Brunscheon

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so I cannot detect selected item/object? – mirelana Aug 09 '13 at 17:52
Your selected item is going to be whatever object type this returns: parser.LevelCollection – Joe Brunscheon Aug 09 '13 at 18:45
Looks like the type is: LocalXmlParsing.XMLParser. – Joe Brunscheon Aug 09 '13 at 18:58
Yes, but how can I convert/parse it? – mirelana Aug 09 '13 at 19:04
You need to use the parser to parse your XML into concrete types. Something like this should help: http://stackoverflow.com/questions/14226473/c-sharp-parsing-xml-file – Joe Brunscheon Aug 09 '13 at 19:11
I'd try to move towards using XDocuments and parsing that way. You can also try using Linq to XML (plenty of links to look at if you google it). – Joe Brunscheon Aug 09 '13 at 19:12

score 1 · Accepted Answer · answered Aug 10 '13 at 07:33

It looks like you are using Nokia's Sample project called "LocalXmlParsing". You can still use your code, but if you want to detect SelectedItem you should use something like this:

LocalXmlParsing.Level selecteditem = (LocalXmlParsing.Level)myListBox.SelectedItem; //it will returns your element
MessageBox.Show(selecteditem.Id); //It will return the Id of SelectedItem (String). You should use yours: SelectedItem.MyElement

Windows Phone 7: ListBox SelectionChanged event

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