将新项添加到ItemsSource时更新ItemsControl

Question

Okay this seems like a pretty easy thing to do, but I've been looking for a solution for over an hour and couldn't come up with anything. In my WP8 application, I have an ItemsControl which I bind data procedurally. The bound data is a static ObservableCollection . When I add new items to this collection via another page, I expect to see the new item on my ItemsControl . After adding a new item to the collection, the ItemsControl still looks empty, even though its ItemsSource seems to contain items.

Edit: The code I wrote looks like below

The ItemsControl is defined on the page as follows:

<ItemsControl Name="MyItemsControl" 
                              Grid.Row="4"
                              Grid.ColumnSpan="2">
                    <ItemsControl.ItemTemplate>
                        <DataTemplate>
                            <Grid>
                                <TextBlock Text="{Binding someData}" 
                                           Margin="24"
                                           Foreground=""/>
                            </Grid>
                        </DataTemplate>
                    </ItemsControl.ItemTemplate>
                </ItemsControl>

Binding is handled as follows:

protected override void OnNavigatedTo(NavigationEventArgs e)
{
     MyItemsControl.ItemsSource = SomeClass.myObservableCollection;
}

Class where the static collection resides:

class SomeClass 
{
    public static ObservableCollection<MyData> myObservableCollection { set; get;}
}

MyData:

class MyData
{
    public string someData { set; get; }
}

Answer 1

I think the problem is that your ObservableCollection is null, if you want to use property it can look like this:

class SomeClass
{
    private static ObservableCollection<MyData> myObservableCollection = new ObservableCollection<MyData>();

    public static ObservableCollection<MyData> MyObservableCollection
    {
         get { return SomeClass.myObservableCollection; }
         set { SomeClass.myObservableCollection = value; }
    }         
}

Then:

MyItemsControl.ItemsSource = SomeClass.MyObservableCollection;
SomeClass.MyObservableCollection.Add(new MyData() { someData = "Romasz" });

And of course it can be even easier (if you don't need property):

public static ObservableCollection<MyData> myObservableCollection = new ObservableCollection<MyData>();

And you can move MyItemsControl.ItemsSource = SomeClass.MyObservableCollection; to the constructior of your Page - there is no need to do it every time you Navigate to the Page.

And remove Foreground="" from your XAML code.

EDIT - after comment
It's hard to say for me where can be a problem as I don't see your whole code, but please consider this example which works fine for me:
In XAML:

<ItemsControl Name="MyItemsControl" Grid.Row="3">
      <ItemsControl.ItemTemplate>
            <DataTemplate>
               <Grid>
                  <TextBlock Text="{Binding someData}" Margin="24"/>
               </Grid>
            </DataTemplate>
       </ItemsControl.ItemTemplate>
</ItemsControl>

In code behind:

class SomeClass
{
   public static ObservableCollection<MyData> myObservableCollection = new ObservableCollection<MyData>();
}

class MyData
{
   public string someData { set; get; }
}

public MainPage()
{
   InitializeComponent();

   MyItemsControl.ItemsSource = SomeClass.myObservableCollection;
   SomeClass.myObservableCollection.Add(new MyData() { someData = "First" });
   SomeClass.myObservableCollection.Add(new MyData() { someData = "Second" });
}

Answer 2

Here is example of updating data

private void UpdateData()
        {
            try
            {
                MainWindow.cmdSel = new SqlCommand("SELECT Name FROM Cities order by ID asc", MainWindow.conn);
                DataSet dtst = new DataSet();
                SqlDataAdapter adpt = new SqlDataAdapter(); 
                try
                {

                    adpt.SelectCommand = MainWindow.cmdSel;
                    adpt.Fill(dtst, "Cities");
                    lstCity.DataContext = dtst;

                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }


            }
            catch (SqlException ex)
            {
                MessageBox.Show(ex.Message);

            }
        }

After you add some items in your ListItem

    private void AddCity(object sender, MouseButtonEventArgs e)
    {
        if (TxtCity.Text != string.Empty)
        {
            Add(TxtCity.Text);
            UpdateData();           ////Here I am updating my listitem
        }
        else
        {
            MessageBox.Show("Add city");
        }

    }