Two windows connected to database, how to update the UI?

Question

I have two windows one to add users and the other to view all the users, both of them are connected the database. What I want is to show the user automatically in the view all windows after I press the add button in the add users window (before closing it).

In view all window (I am posing the data binding parts only):-

Note:

• The following code is in the constructor of MainWindows.xaml.

• Basically the ProfileControl is a custom control, profileList is ListBox and profileCollection is an ObservableCollection

  if (dbObj.GetDbData().Count != 0)
  {
      foreach (ProfileControl item in dbObj.GetDbData())
      {
          profileCollection.Add(item);
      }
      this.profileList.DataContext = profileCollection;
  }
  

The following is for the ListBox.

<ListBox Name="profileList" ItemsSource="{Binding}" IsSynchronizedWithCurrentItem="True">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <profileControl:ProfileControl Name="pcList" onClickUser="ProfileControl_onClickUser" />
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.ItemsPanel>
                <ItemsPanelTemplate>
                    <StackPanel Orientation="Horizontal" VerticalAlignment="Top"/>
                </ItemsPanelTemplate>
            </ListBox.ItemsPanel>
        </ListBox>

And lastly the following is the add button which is in a AddUser.xaml.

Note: Basically I am checking first that the user I am adding is check-in or not. If not I am adding it to the database.

private void addButton_Click(object sender, RoutedEventArgs e)
    {
        try
        {
            if (co.checkIfCheckedIn(memoryCard))
            {
                MessageBox.Show("The person is inside. ", "No Adding", MessageBoxButton.OK, MessageBoxImage.Stop);
            }
            else
            {
                co.AddData(memoryCard, emailTb.Text, contactNumberTb.Text, workPlaceTb.Text, infoTb.Text);
                MessageBox.Show("Saving is done. ", "Saved", MessageBoxButton.OK, MessageBoxImage.Asterisk);
                this.notificationTB.Text = " Saving is complete.";
            }


        }
        catch (Exception ex)
        {
            this.notificationTB.Text = ex.Message;
            this.notificationTB.Foreground = (Brush)new BrushConverter().ConvertFromString("White");
            this.notificationTB.Background = (Brush)new BrushConverter().ConvertFromString("Red");
        }
    }

I want to add that, it should after I save the data by the add button shows the user in the MainWindows automatically, but it not. And I have to close the application and open it again to view the data. I believe I need to access the ObservableCollection object profileCollection in the MainWindows.xaml to do this but I am not sure if it is right and how.

Please advise me, thank.

Answer 1

There is at least 3 solutions from the simplest (bad from a dogmatic "decouple them all" POV but can be pragmatic) to the mass plumbing (good from a design POV):

1) share your collections via a global resource in Application.Current.Resources:

Application.Current.Resources["MyUserCollection"] = theUserCollection;

2) use a ViewModel shared by both views, exposing the users collection; you'll typically set it as the DataContext of both views

3) use a message broker to inform the main view that a new user was added, you'll need some MVVM framework for that like MVVM Light or Caliburn Micro

---

EDIT: here is another solution which is a good compromise:

4) in your MainWindow code-behind expose a Refresh/Reload method:

public void ReloadUsers()
{
    profileCollection.Clear();

    var data = dbObj.GetDbData();

    if (data.Count != 0)
    {
        foreach (ProfileControl item in data)
        {
            profileCollection.Add(item);
        }
        this.profileList.DataContext = profileCollection;
    }
}

And call it from your other Window:

private void addButton_Click(object sender, RoutedEventArgs e)
{
    try
    {
        ...

        (Application.Current.MainWindow as MainWindow).ReloadUsers();
    }
    catch (Exception ex)
    {
        ...
    }
}