UI does not update when using a backgroundworker and binding in xaml

Question

I am currently trying to update a text box in my UI, through a backgroundworker class. This backgroundworker is in my ViewModel section of my solution, and it only occurs when my application receives data (triggered as an event on my Model).

I have used binding in my MainWindow xaml file to bind the text to properties in my ViewModel, and when breakpoints are set it appears to store the correct values, even though they are still not displayed.

I am not too sure about the split between the DoWork event & the RunWorkerCompleted event. I have the DoWork event setting the data packet to whatever the latest packet received is, and on completion (RunWorkerCompleted), I am assigning the value to the property created in the ViewModel. Have I implemented the backgroundworker class correctly?

Any help on this would greatly be appreciated.

View

<TextBox Height="23" HorizontalAlignment="Left" Margin="577,70,0,0" Name="receiveVariableValueBox" VerticalAlignment="Top" Width="120" Text="{Binding Path=RxVariableValue}"/>

ViewModel

public class DataPointsViewModel : INotifyPropertyChanged
{
    public Model model;

    BackgroundWorker receiveBackground;
    RRTDataPacket rxDataPacket = new RRTDataPacket();

    private int rxVariableValue;
    public int RxVariableValue
    {
        get { return rxVariableValue; }
        set
        {
            if(rxVariableValue != value)
            {
                rxVariableValue = value;
                OnPropertyChanged(rxMajorVersion.ToString());
            }
        }
    }

    public void receivingUpdater(object sender, EventArgs e)
    {
        receiveBackground = new BackgroundWorker();
        receiveBackground.DoWork += new DoWorkEventHandler(receiveBackground_DoWork);            
        receiveBackground.RunWorkerCompleted += new RunWorkerCompletedEventHandler(receiveBackground_RunWorkerCompleted);
        receiveBackground.RunWorkerAsync();
    }

    public void receiveBackground_DoWork(object sender, DoWorkEventArgs e)
    {  
        try
        {
            if (rxDataPacket != Engine.latestRxDataPacket)
            {
                rxDataPacket = Engine.latestRxDataPacket;
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }           
    }

    public void receiveBackground_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        if(rxDataPacket != null)
        {
            RxMajorVersion = (int)rxDataPacket.majorVersion;
            RxVariableValue = (int)rxDataPacket.variableValue;
        }
    }

possible duplicate of [WPF: UI not being updated with INotifyPropertyChanged](http://stackoverflow.com/questions/25162817/wpf-ui-not-being-updated-with-inotifypropertychanged) — Daniel Kelley, Sep 30 '14 at 13:08

paparazzo · Accepted Answer · 2014-09-30T13:09:55.227

1

You have the OnPropertyChanged wrong

public int RxVariableValue
{
    get { return rxVariableValue; }
    set
    {
        if(rxVariableValue != value)
        {
            rxVariableValue = value;
            OnPropertyChanged("RxVariableValue");
        }
    }
}

edited Sep 30 '14 at 13:09

answered Sep 30 '14 at 13:04

paparazzo

44,497
23
105
176

score 0 · Answer 2 · answered Sep 30 '14 at 13:00

0

Try calling OnPropertyChanged("RxVariableValue"); in the setter of RxVariableValue

answered Sep 30 '14 at 13:00

Andra Ciorici

301
1
7

UI does not update when using a backgroundworker and binding in xaml

View

ViewModel

2 Answers2