WPF percentage status shown in label MVVM

Question

I got some problem in showing download percentage in GridView of WCF. I used MVVM pattern.

Here is my background worker in application start:

public partial class MainWindow : Window
   {
       public MainWindow()
       {
           Overall.EverythingOk = "Nothing";

           InitializeComponent();
           //IRepo repo = new Repo();
           ViewModel.MainWindowsViewModel viewModel = new ViewModel.MainWindowsViewModel();
           this.DataContext = viewModel;     
           BackGroundThread bgT = new BackGroundThread();
           bgT.bgWrk.RunWorkerAsync();
       }}

Here is the DoWork function in BackGroundTHread class

 public void bw_DoWork(object sender, DoWorkEventArgs e)
   {
       if (!Overall.stopStatus)
       {
           for (int i=0; i < 10000; i++)
           {
               Overall.PercentageDwnd = i;
               Overall.caseRefId = "999999";
               if (i == 9998)
               {
                   i = 1;
               }
           }
       }
   }

Overall.PercentageDwnd and Overall.caseRefId are static variable (you can call from everywhere in the application) and always update until the background worker completed. I got another ViewModel called TestViewModel and here it is.

public class TestViewModel:BindableBase
    {        
        private String _UpdatePer=Overall.PercentageDwnd.ToString();
        public String UpdatePercentage
        {
            get { return _UpdatePer; }
            set { SetProperty(ref _UpdatePer, value); }
        }

        private ObservableCollection _ViewAKA = new ObservableCollection();
        private tblTransaction model;

        public TestViewModel(tblTransaction model)
        {
            // TODO: Complete member initialization

        }
        public ObservableCollection ViewAKA
        {
            get { return _ViewAKA; }
            set { SetProperty(ref _ViewAKA, value); }
        }
    }

I bind with TestView.xaml file

    <Window x:Class="EmployeeManager.View.TestView"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="TestView" Height="359.774" Width="542.481">
    <Grid Margin="0,0,2,0">
        <Label Content="{Binding UpdatePercentage,UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Background="Red" Foreground="White" Margin="130,86,0,0" VerticalAlignment="Top" Width="132" Height="39">            
        </Label> 
    </Grid>
</Window>

There is no real time update at Label even though I bind UpdatePercentage to it. How can I update real time to label?

Answer 1

Here is answer link:

https://social.msdn.microsoft.com/Forums/vstudio/en-US/02a7b9d1-1c26-4aee-a137-5455fee175b9/wpf-percentage-status-shown-in-label-mvvm?forum=wpf

i need to trigger when the Overall.PercentageDwnd property changes.

Edited

In Overall Class:

public class Overall
{
    private static int _percentage;
    public static int PercentageDwnd
    {
        get { return _percentage; }
        set
        {
            _percentage = value;
            //raise event:
            if (PercentageDwndChanged != null)
                PercentageDwndChanged(null, EventArgs.Empty);
        }
    }

    public static string caseRefId { get; set; }
    public static bool stopStatus { get; set; }

    public static event EventHandler PercentageDwndChanged;
}

In TestViewModel:

public class TestViewModel : BindableBase
{
    private String _UpdatePer = Overall.PercentageDwnd.ToString();
    public String UpdatePercentage
    {
        get { return _UpdatePer; }
        set { SetProperty(ref _UpdatePer, value); }
    }

    public TestViewModel(tblTransaction model)
    {
        Overall.PercentageDwndChanged += Overall_PercentageDwndChanged;

        // TODO: Complete member initialization
    }

    private void Overall_PercentageDwndChanged(object sender, EventArgs e)
    {
        this.UpdatePercentage = Overall.PercentageDwnd.ToString();
    }
}

Since you have bound the TextBlock in the view to the UpdatePercentage source property, you need to set this one and raise the PropertyChanged event whenever you want to update the Label in the view. This means that you need to know when the Overall.PercentageDwnd property changes.

Credit to Magnus (MM8) (MCC, Partner, MVP)

Thanks All

Answer 2

The problem is that you are updating the static properties, which are not bound to anything. You need to update and raise the property changed notification for the properties which are bound to the label controls, i.e. UpdatePercentage

Can you pass the TestViewModel instance into the RunWorkerAsync call?

bgT.bgWrk.RunWorkerAsync(testViewModel);

And then access in the DoWork event handler:

public void bw_DoWork(object sender, DoWorkEventArgs e)
{
   if (!Overall.stopStatus)
   {
       var viewModel = e.Argument as TestViewModel;
       for (int i=0; i < 10000; i++)
       {
           Overall.PercentageDwnd = i;
           viewModel.UpdatePercentage = i;
           Overall.caseRefId = "999999";
           if (i == 9998)
           {
               i = 1;
           }
        }
    }
}