Binding and INotifyPropertyChanged

Question

I'm trying to bind a TextBlock using INotifyPropertyChanged event. But it is not updating anything to the TextBlock. The TextBlock is blank. My goal is to update the status of items which are displayed in different rows. I need to update the TextBlock's text and color based on the status.

Could anyone tell me what is wrong with my code?

public class ItemStatus : INotifyPropertyChanged
{
    string itemStatus;
    Brush itemStatusColor;

    public string ItemStatus
    {
        get { return itemStatus; }
        set
        {
            itemStatus = value;
            this.OnPropertyChanged("ItemStatus");
        }
    }

    public Brush ItemStatusColor
    {
        get { return itemStatusColor; }
        set
        {
            itemStatusColor = value;
            this.OnPropertyChanged("ItemStatusColor");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    void OnPropertyChanged(string propName)
    {
        if (this.PropertyChanged != null)
            this.PropertyChanged(
                this, new PropertyChangedEventArgs(propName));
    }
}

public class Items
{
    List<ItemStatus> currentItemStatus;

    public List<ItemStatus> CurrentItemStatus
    {
        get { return currentItemStatus; }
        set { currentItemStatus = value; }
    }
}

public partial class DisplayItemStatus : Page
{
    ....
    ....

    public DisplayItemStatus()
    {
        foreach (Product product in lstProductList)
        {
            TextBlock tbItemStatus = new TextBlock();
            ....

            Items objItems = new Items();

            Binding bindingText = new Binding();
            bindingText.Source = objItems;
            bindingText.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
            bindingText.Path = new PropertyPath(String.Format("ItemStatus"));
            tbItemStatus.SetBinding(TextBlock.TextProperty, bindingText);

            Binding bindingColor = new Binding();
            bindingColor.Source = objItems;
            bindingColor.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
            bindingColor.Path = new PropertyPath(String.Format("ItemStatusColor"));
            tbItemStatus.SetBinding(TextBlock.ForegroundProperty, bindingColor);

            grdItemsList.Children.Add(tbItemStatus);
        }
    }

    private void UpdateItems_Click(object sender, MouseButtonEventArgs e)
    {
        int intCount = 0;

        List<Product> ProductList = new List<Product>();
        List<ItemStatus> ItemList = new List<ItemStatus>();

        ProductList = GetProducts();
        foreach (Product product in ProductList)
        {
            intCount++;
            UpdateStatus(intCount, ItemList);
        }
    }

    public void UpdateStatus(int intIndex, List<ItemStatus> ItemList)
    {
        ItemStatus status = new ItemStatus();
        status.ItemStatus = strOperationStatus;
        status.ItemStatusColor = brshForegroundColor;
        ItemList.Add(status);
    }
}

Answer 1

Well, the specific problem here is that you're binding the TextBlock to an Item and not the ItemStatus. But you're also doing things the hard way, you really should do the binding details in XAML. Expose a collection of ItemStatus's from your view model, and have a ListBox or something with its ItemsSource bound to the collection. Then you'll need a DataTemplate which defines the TextBlock and the bindings to the ItemStatus.

Here's a good walkthrough for it in general