Prevent selected row from refreshing in DataGrid

Question

I am using DataGrid for my application and I am using timer to update the datagrid from Database. The timer refreshes every 5 sec to see if there is new data. If there is any new data it updates in the datagrid. But it also resets everything in the datagrid and i loose selected index.

How do i prevent the selected item from updating or changing while other rows updates??

DataGrid

public void InitTimer()
{
    Timer timer1 =  new Timer();
    timer1.Elapsed += Timer1_Elapsed;
    timer1.Interval = 5000; // in milliseconds
    timer1.Start();
}

private void Timer1_Elapsed(object sender, ElapsedEventArgs e)
{
    Application.Current.Dispatcher.Invoke((Action)(() =>
    {
        dataGrid1.ItemsSource = AddData(dataGrid1);
    }));
}

Answer 1

I already wrote in my comment that I would highly advice against manipulating your ItemsSource in your code-behind file (.xaml.cs) of your view.

Nevertheless I try to help you with your problem:

The problem you describe occurs because of setting the ItemsSource property each tick of the timer. Maybe something like this could work:

// This is the collection to bind your datagrid to
public ObservableCollection<YourObject> Data { get; } = new ObservableCollection<YourObject>();

// This method needs to be called once (preferably in the constructor)
private void InitDataGrid() 
{
    dataGrid1.ItemsSource = this.Data;
}

private void Timer1_Elapsed(object sender, ElapsedEventArgs e)
{
    Application.Current.Dispatcher.Invoke((Action)(() =>
    {
        // Here you need to call a method which modifies the Data property.
        // Try removing, inserting, updating the items directly to the collection.
        // Do not set the ItemsSource directly, instead manipulate the ObservableCollection.
    }));
}

Answer 2

You could try to save the index before you re-set the ItemsSource and then set it back afterwards:

private void Timer1_Elapsed(object sender, ElapsedEventArgs e)
{
    Application.Current.Dispatcher.Invoke((Action)(() =>
    {
        int index = dataGrid1.SelectedIndex;
        dataGrid1.ItemsSource = AddData(dataGrid1);
        dataGrid1.SelectedIndex = index;
    }));
}