Question

Im struggling with Observable collections and using it to add pushpins onto a silverlight bing map. Im trying to build up a collection here using Linq. But im getting the error under every “PushPinItems” instance in my code saying:

'observable_collection_test.Map.PushPinItems' is a 'field' but is used like a 'type' c:\users\dan\documents\visual studio 2010\Projects\observable collection test\observable collection test\Map.xaml.cs 26 38 observable collection test

Not sure whats going on here, am I declaring/constructing it wrong or something?
Im new to Observable collections (and most of c#!) so any help/advice welcome. Many thanks.

UPDATE:

This seems to be ok now, the above issue, but now its not binding my items to pushpins.
I have looked at the “PushPins = pushPinCollection;” method and all 143 items are in there with lat, long and location propertiess with the correct data- as per this breakpoint:

Maybe there is an issue with my XAML binding?

Here is the updated code:

  namespace observable_collection_test
 {
public partial class Map : PhoneApplicationPage
{

    private ObservableCollection<SItem2> _PushPins;

    public event PropertyChangedEventHandler PropertyChanged;

    public Map()
    {
        InitializeComponent();

        getItems();
    }

    public ObservableCollection<SItem2> PushPins
    {
        get
        {
            return _PushPins;
        }


        private set
        {
            _PushPins = value;
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("PushPins"));
            }


        }
    }
    private GeoCoordinate _location;

    public GeoCoordinate Location
    {
        get { return _location; }
        set
        {
            if (_location != value)
            {
                _location = value;
                               }
        }
    }

    private string _pinSource;

    public string PinSource
    {
        get { return _pinSource; }
        set
        {
            if (_pinSource != value)
            {
                _pinSource = value;
                                }
        }
    }

    public void getItems()
    {
         var document = XDocument.Load("ListSmall.xml");

         if (document.Root == null)
            return;

          var xmlns = XNamespace.Get("http://www.blahblah.co.uk/blah");

         var events = from ev in document.Descendants("item")
          select new
          {
           Latitude = Convert.ToDouble(ev.Element(xmlns + "Point").Element(xmlns + "lat").Value),
            Longitude = Convert.ToDouble(ev.Element(xmlns + "Point").Element(xmlns + "long").Value),

         };

         ObservableCollection<SItem2> pushPinCollection = new ObservableCollection<SItem2>();

          foreach (var ev in events)

                         {
                           SItem2 PushPin = new SItem2
                (                    ev.Latitude, ev.Longitude)
            {

            };

            pushPinCollection.Add(PushPin);

        }
        PushPins = pushPinCollection;


    }

other class:

namespace observable_collection_test
 {

public class SItem2
    {
    //public DateTimeOffset Date { get; set; }
    //public string Title
    //{ get; set; }
    public double Latitude
    { get; set; }
    public double Longitude
    { get; set; }
    public GeoCoordinate Location
    { get; set; }
    //public Uri Link { get; set; }


    public SItem2(//string Title, 
        double Latitude, double Longitude)
    {
        //this.Date = Date;
        //this.Title = Title;
        this.Latitude = Latitude;
        this.Longitude = Longitude;
        //this.Location = Location;
        //this.Link = Link;
    }
}

Bit of XAML concerning adding pins to map:

      <my:Map ZoomBarVisibility="Visible" ZoomLevel="10" CredentialsProvider="AhqTWqHxryix_GnWER5WYH44tFuutXNEPvFm5H_CvsZHQ_U7-drCdRDvcWSNz6aT"  Height="508" HorizontalAlignment="Left" Margin="0,22,0,0" Name="map1" VerticalAlignment="Top" Width="456">
                                        <my:MapItemsControl ItemsSource="{Binding PushPins}" >
                <my:MapItemsControl.ItemTemplate>
                    <DataTemplate>
                        <my:Pushpin Background="Aqua" Location="{Binding Location}" ManipulationCompleted="pin_click">
                        </my:Pushpin>
                    </DataTemplate>
                </my:MapItemsControl.ItemTemplate>
            </my:MapItemsControl>

        </my:Map> 

It would also be good to know if I am approaching the pushpin binding to the maps in the right way.

Answer 1

It looks as if this is because you have used x:Name="PushPinItems" in your XAML which is the same name as one of your types, so when you think you are referencing your PushPinItems type in your codebehind, you are actually referencing the field that VS has generated for you from your XAML that represents that Pushpin instance. You could use a different x:Name in your XAML.

Update

Ok, I see the issue 🙂 I haven’t worked with the Bing maps control before, but looking at http://forums.silverlight.net/forums/t/197631.aspx (second post down), you need to set the map controls MapItemsControl property. The ItemsSource property here should be bound to your ObservableCollection of a custom type which contains properties such as Name and Location. You can then populate this collection with instances of this custom type (in the post they have used MapData as the type name).

You can also get more examples and source code at http://www.microsoft.com/maps/isdk/silverlight/