LongListSelector and ObservableCollection throws InvalidCastException

LongListSelector and ObservableCollection throws InvalidCastException

I'm trying to bind my collection to LLS, but I get an InvalidCastException. If i use ListBox instead of LLS - all binds work fine and good. Here is my collection:

    public class Friend : INotifyPropertyChanged {     private string name;     public string Name { get { return name; } set { name = value; OnPropertyChanged("Name"); } }     private string image;     public string Image { get { return image; } set { image = value; OnPropertyChanged("Image"); } }     private string sourseId;     public string SourseId { get { return sourseId; } set { sourseId = value; OnPropertyChanged("SourseId"); } }     private string online_image;     public string Online_Image { get { return online_image; } set { online_image = value; if (online_image == "1") online_image = @"/icons/appbar.power.png"; OnPropertyChanged("Online_Image"); } }     public event PropertyChangedEventHandler PropertyChanged;     protected void OnPropertyChanged(string info)     {         PropertyChangedEventHandler handler = PropertyChanged;         if (handler != null)         {             handler(this, new PropertyChangedEventArgs(info));         }     }     public Friend() { }   } public class FriendList : ObservableCollection<Friend> {     public FriendList()         : base()     {      } } 

And here is the way i bind it to LLS:

            XDocument xml = XDocument.Load(e.Result);       //  MessageBox.Show(xml.ToString());         var users = from c in xml.Descendants("user")                     select c;         foreach (var user in users)         {             Friend fr = new Friend();             fr.SourseId = (string)user.Element("uid").Value;             fr.Image = (string)user.Element("photo_medium").Value;             fr.Name = (string)user.Element("first_name").Value + " " + (string)user.Element("last_name").Value;             fr.Online_Image = (string)user.Element("online").Value;             if (fr.Online_Image == "1") fr.Online_Image = @"/icons/appbar.power.png";             FriendList.Add(fr);         }         this.AllFriendsList.ItemsSource = FriendList; 

and public FriendList FriendList = new FriendList(); is just under the page ctor. What i'm doing wrong? Exception fires on string this.AllFriendsList.ItemsSource = FriendList;

And here is my xaml:

                    <toolkit:LongListSelector Name="AllFriendsList" ItemsSource="{Binding FriendList}">                     <toolkit:LongListSelector.ItemTemplate>                         <DataTemplate>                             <Grid Height="75" Width="460" Margin="0,10,10,0">                                 <Line Style="{StaticResource Line1}" ></Line>                                 <Line Style="{StaticResource Line2}" ></Line>                                 <TextBlock Margin="75,15,40,0" FontSize="30" Name="Name" Text="{Binding Name}" Tap="GetUserInfo" />                                 <Image HorizontalAlignment="Left" Width="75" Name="Photo" >                                     <Image.Source>                                         <BitmapImage UriSource="{Binding Image}" CreateOptions="BackgroundCreation" />                                     </Image.Source>                                 </Image>                                 <Image HorizontalAlignment="Right" Name="IsOnline" Margin="0,0,0,0" Width="60" Height="60" Source="{Binding Online_Image}" />                             </Grid>                         </DataTemplate>                     </toolkit:LongListSelector.ItemTemplate>                 </toolkit:LongListSelector> 

UPD: If I use group such as in this example, and group my list like

            var FriendsGroup = from fr in FriendList                             group fr by fr.Online_Image into c                             orderby c.Key                             select new Group<Friend>(c.Key, c);          AllFriendsList.ItemsSource = FriendsGroup; 

it works fine. If I understand correct - LLS waiting a grouped source.

Answers & Comments...

Answer: 1

You are binding twice to the your AllFiendsList. The first time through the xaml here

<toolkit:LongListSelector Name="AllFriendsList" ItemsSource="{Binding FriendList}"> 

The second time through code. That may cause the exception.

by : derStevehttp://stackoverflow.com/users/36475

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