How to update database automatically from ObervableCollection

Question

Hi, I want to update the database automatically every time I make a change in ObervableCollection.
Until now I have updated the Databese directly after the changes in ObservableCollection. Is there a better way?

After editing an item in the ListView, the Database was not updated. Can someone tell me why this is not happening?

The connection to Databese takes a long time. am I doing something wrong? Or is there a better way?

Thanks
Sarah

MainWindow

Code

using System.Windows;


namespace MyContacts
{
    /// 
    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            ViewModel.Instance.FillList();
            this.DataContext = ViewModel.Instance; 
        }

        private void Add_Click(object sender, RoutedEventArgs e)
        {
            var addContactWindow = new AddContactWindow();
            ContactDetail contactData = new ContactDetail();
            addContactWindow.DataContext = contactData;
            addContactWindow.ShowDialog();
            if (addContactWindow.DataContext != null)
            {
                ViewModel.Instance.ContactDetails.Add(contactData);
                ViewModel.Instance.AddContactToDB(contactData);
                ViewModel.Instance.OnPropertyChanged("View");
            }
        }

        private void Edit_Click(object sender, RoutedEventArgs e)
        {
            if (ContactListView.SelectedItem != null)
            {
                ContactDetail contactData = ContactListView.SelectedItem as ContactDetail;
                if (contactData == null)
                {
                    return;
                }
                else
                {
                    var addContactWindow = new AddContactWindow();
                    contactData.Cache();
                    addContactWindow.DataContext = contactData;
                    addContactWindow.ShowDialog();
                    if (addContactWindow.DataContext == null)
                    {
                        contactData.Restore();
                    }
                }
            }
        }

        private void Remove_Click(object sender, RoutedEventArgs e)
        {
            if (ContactListView.SelectedItem != null)
            {
                MyContacts.ViewModel.Instance.ContactDetails.Remove((ContactDetail)ContactListView.SelectedItem);
                ViewModel.Instance.RemoveContactFromDB((ContactDetail)ContactListView.SelectedItem);
            }
        }
    }
}

AddContactWindow

Code

using System.Windows;

namespace MyContacts
{
    /// 
    /// Interaktionslogik für Contact.xaml
    /// 
    public partial class AddContactWindow : Window
    {
        public AddContactWindow()
        {
            InitializeComponent();
        }

        private void Close_Click(object sender, RoutedEventArgs e)
        {
            this.DataContext = null;
            Close();
        }

        private void Save_Click(object sender, RoutedEventArgs e)
        {
            Close();
        }
    }
}

ContactDetail

using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows.Data;

namespace MyContacts
{
    public class ContactDetail : INotifyPropertyChanged
    {
        private int _Id;
        private string _Firstname;
        private string _Lastname;
        private string _Address;
        private string _Phone;
        private string _Email;
        private DateTime _Birthday = DateTime.Now;
        private string _Specialty;


        public ContactDetail() { }

        public event PropertyChangedEventHandler PropertyChanged;

        protected void OnPropertyChanged([CallerMemberName] string name = "") =>
          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));


        #region Properties Getters and Setters

        public int Id
        {
            get { return _Id; }
            set { _Id = value; OnPropertyChanged(); }
        }

        public string Firstname
        {
            get { return _Firstname; }
            set { _Firstname = value; OnPropertyChanged(); }
        }

        public string Lastname
        {
            get { return _Lastname; }
            set { _Lastname = value; OnPropertyChanged(); }
        }

        public string Address
        {
            get { return _Address; }
            set { _Address = value; OnPropertyChanged(); }
        }

        public string Phone
        {
            get { return _Phone; }
            set { _Phone = value; OnPropertyChanged(); }
        }

        public string Email
        {
            get { return _Email; }
            set { _Email = value; OnPropertyChanged(); }
        }

        public DateTime Birthday
        {
            get { return _Birthday; }
            set { _Birthday = value; OnPropertyChanged(); }
        }

        public string Specialty
        {
            get { return _Specialty; }
            set { _Specialty = value; OnPropertyChanged(); }
        }

        #endregion Properties Getters and Setters

        private int _Id_Cache;
        private string _Firstname_Cache;
        private string _Lastname_Cache;
        private string _Address_Cache;
        private string _Phone_Cache;
        private string _Email_Cache;
        private DateTime _Birthday_Cache;
        private string _Specialty_Cache;

        public void Cache()
        {
            _Id_Cache = _Id;
            _Firstname_Cache = _Firstname;
            _Lastname_Cache = _Lastname;
            _Address_Cache = _Address;
            _Phone_Cache = _Phone;
            _Email_Cache = _Email;
            _Birthday_Cache = _Birthday;
            _Specialty_Cache = _Specialty;
        }
        public void Restore()
        {
            Id = _Id_Cache;
            Firstname = _Firstname_Cache;
            Lastname = _Lastname_Cache;
            Address = _Address_Cache;
            Phone = _Phone_Cache;
            Email = _Email_Cache;
            Birthday = _Birthday_Cache;
            Specialty = _Specialty_Cache;
        }
    }

    public class ViewModel : INotifyPropertyChanged
    {

        private static ViewModel _instance;
        static ViewModel()
        {
            _instance = new ViewModel();
            _instance.ContactDetails = new ObservableCollection();
            _instance.cvs.Source = _instance.ContactDetails;
        }

        public static ViewModel Instance { get => _instance; }

        public ICollectionView View { get => cvs.View; }
        private CollectionViewSource cvs = new CollectionViewSource();

        public ObservableCollection? ContactDetails { get; set; }


        public event PropertyChangedEventHandler? PropertyChanged;
        internal void OnPropertyChanged([CallerMemberName] string name = "") =>
          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));

        AppDbContext db = new AppDbContext();

        public void FillList()
        {

            ContactDetails.Clear();
            var contactData = db.tblContact.ToList();

            foreach (var contact in contactData)
            {
                ContactDetails.Add(contact);
            }
        }

        public void RemoveContactFromDB(ContactDetail contact)
        {
                db.tblContact.Remove(contact);
                db.SaveChanges();
        }

        public void AddContactToDB(ContactDetail contact)
        {
                db.tblContact.Add(contact);
                db.SaveChanges();
        }

    }
}

Class AppDbContext

using Microsoft.EntityFrameworkCore;

namespace MyContacts
{
    public class AppDbContext : DbContext
    {
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=...\ContactDB.mdf;Integrated Security=True");
        }

        public DbSet tblContact { get; set; }
    }
}

Answer

Hi Sarah,
use SaveChange after Dialog like in following demo with your code:

XAML MainWindow:

XAML ContactWindow:

and classes:

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Data;
using System.Windows.Input;
using WpfApp1;

namespace WpfApp004
{
  public class ViewModel : FrameworkElement, INotifyPropertyChanged
  {
    AppDbContext ctx = new AppDbContext();
    public ICollectionView View
    {
      get
      {
        ctx.tblContact.Load();
        cvs.Source = ctx.tblContact.Local.ToObservableCollection();
        cvs.View.Refresh();
        return cvs.View;
      }
    }
    private CollectionViewSource cvs = new CollectionViewSource();
    public ObservableCollection? ContactDetails { get; set; }

    private ContactDetail _currentContact;
    public ContactDetail CurrentContact { get => this._currentContact; set { this._currentContact = value; OnPropertyChanged(nameof(Cmd)); } }

    private Window004A addContactWindow;
    private bool? ret;

    public ICommand Cmd { get { return new RelayCommand(CmdExecute, CmdCanExecute); } }

    public event EventHandler? CanExecuteChanged;
    public void CmdExecute(object parameter)
    {
      switch (parameter.ToString())
      {
        case "Add_Click":
          addContactWindow = new Window004A() { DataContext = this };
          CurrentContact = new ContactDetail();
          ret = addContactWindow.ShowDialog();
          if (ret.HasValue && ret.Value) ctx.tblContact.Add(CurrentContact);
          else CurrentContact = null;
          ctx.SaveChanges();
          break;
        case "Edit_Click":
          if (CurrentContact != null)
          {
            addContactWindow = new Window004A() { DataContext = this };
            ret = addContactWindow.ShowDialog();
            if (ret.HasValue && ret.Value) ctx.SaveChanges();
            else
            {
              ctx.Entry(CurrentContact).State = EntityState.Unchanged;
              OnPropertyChanged(nameof(View));
            }
          }
          break;
        case "Remove_Click":
          if (CurrentContact != null) ctx.tblContact.Remove(CurrentContact);
          ctx.SaveChanges();
          break;
        case "Close_Click":
          addContactWindow.DialogResult = false;
          break;
        case "Save_Click":
          addContactWindow.DialogResult = true;
          break;
        default:
          break;
      }
    }

    public bool CmdCanExecute(object parameter) =>
      ((parameter.ToString() != "Edit_Click" && parameter.ToString() != "Remove_Click") || CurrentContact != null);

    public event PropertyChangedEventHandler? PropertyChanged;
    internal void OnPropertyChanged([CallerMemberName] string name = "") =>
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
  }

  public class AppDbContext : DbContext
  {
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) =>
      optionsBuilder.UseSqlServer(WpfApp1.Properties.Settings.Default.cnSQL);

    public DbSet tblContact { get; set; }
  }

  public class ContactDetail : INotifyPropertyChanged
  {
    #region private fields
    private string _Firstname = String.Empty;
    private string _Lastname = String.Empty;
    private string _Address = String.Empty;
    private string _Phone = String.Empty;
    private string _Email = String.Empty;
    private DateTime _Birthday = DateTime.Now;
    private string _Specialty = String.Empty;
    #endregion

    #region Properties Getters and Setters

    public int ID { get; set; }

    public string Firstname
    {
      get { return _Firstname; }
      set { _Firstname = value; OnPropertyChanged(); }
    }

    public string Lastname
    {
      get { return _Lastname; }
      set { _Lastname = value; OnPropertyChanged(); }
    }

    public string Address
    {
      get { return _Address; }
      set { _Address = value; OnPropertyChanged(); }
    }

    public string Phone
    {
      get { return _Phone; }
      set { _Phone = value; OnPropertyChanged(); }
    }

    public string Email
    {
      get { return _Email; }
      set { _Email = value; OnPropertyChanged(); }
    }
    public DateTime Birthday
    {
      get { return _Birthday; }
      set { _Birthday = value; OnPropertyChanged(); }
    }

    public string Specialty
    {
      get { return _Specialty; }
      set { _Specialty = value; OnPropertyChanged(); }
    }

    #endregion Properties Getters and Setters

    public event PropertyChangedEventHandler? PropertyChanged;
    protected void OnPropertyChanged([CallerMemberName] string name = "") =>
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
  }

  public class RelayCommand : ICommand
  {
    private readonly Predicate

Answer

Hi Sarah,
see following demo without ICommand and ViewModel, all code in CodeBehind:

XAML MainWindow:

XAML ContactWindow:

CodeBehind MainWindow:

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Data;

namespace WpfApp1
{
  public partial class Window005 : Window
  {
    public Window005()
    {
      InitializeComponent();
      DataContext = this;
    }

    AppDbContext ctx = new AppDbContext();
    public ICollectionView View
    {
      get
      {
        ctx.tblContact.Load();
        cvs.Source = ctx.tblContact.Local.ToObservableCollection();
        return cvs.View;
      }
    }
    private CollectionViewSource cvs = new CollectionViewSource();
    public ObservableCollection? ContactDetails { get; set; }

    public ContactDetail CurrentContact { get; set; }

    private Window005A addContactWindow;
    private bool? ret;

    private void Add_Click(object sender, RoutedEventArgs e) => CmdExecute("Add_Click");
    private void Edit_Click(object sender, RoutedEventArgs e) => CmdExecute("Edit_Click");
    private void Remove_Click(object sender, RoutedEventArgs e) => CmdExecute("Remove_Click");
    public void CmdExecute(object parameter)
    {
      switch (parameter.ToString())
      {
        case "Add_Click":
          addContactWindow = new Window005A() { DataContext = this };
          CurrentContact = new ContactDetail();
          ret = addContactWindow.ShowDialog();
          if (ret.HasValue && ret.Value) ctx.tblContact.Add(CurrentContact);
          else CurrentContact = null;
          ctx.SaveChanges();
          break;
        case "Edit_Click":
          if (CurrentContact != null)
          {
            addContactWindow = new Window005A() { DataContext = this };
            ret = addContactWindow.ShowDialog();
            if (ret.HasValue && ret.Value) ctx.SaveChanges();
            else
            {
              ctx.Entry(CurrentContact).State = EntityState.Unchanged;
              cvs.View.Refresh();
              OnPropertyChanged(nameof(View));
            }
          }
          break;
        case "Remove_Click":
          if (CurrentContact != null) ctx.tblContact.Remove(CurrentContact);
          ctx.SaveChanges();
          break;
        default:
          break;
      }
    }

    public event PropertyChangedEventHandler? PropertyChanged;
    internal void OnPropertyChanged([CallerMemberName] string name = "") =>
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));

    public class AppDbContext : DbContext
    {
      protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) =>
        optionsBuilder.UseSqlServer(WpfApp1.Properties.Settings.Default.cnSQL);

      public DbSet tblContact { get; set; }
    }

    public class ContactDetail : INotifyPropertyChanged
    {
      #region private fields
      private string _Firstname = String.Empty;
      private string _Lastname = String.Empty;
      private string _Address = String.Empty;
      private string _Phone = String.Empty;
      private string _Email = String.Empty;
      private DateTime _Birthday = DateTime.Now;
      private string _Specialty = String.Empty;
      #endregion

      #region Properties Getters and Setters

      public int ID { get; set; }

      public string Firstname
      {
        get { return _Firstname; }
        set { _Firstname = value; OnPropertyChanged(); }
      }

      public string Lastname
      {
        get { return _Lastname; }
        set { _Lastname = value; OnPropertyChanged(); }
      }

      public string Address
      {
        get { return _Address; }
        set { _Address = value; OnPropertyChanged(); }
      }

      public string Phone
      {
        get { return _Phone; }
        set { _Phone = value; OnPropertyChanged(); }
      }

      public string Email
      {
        get { return _Email; }
        set { _Email = value; OnPropertyChanged(); }
      }
      public DateTime Birthday
      {
        get { return _Birthday; }
        set { _Birthday = value; OnPropertyChanged(); }
      }

      public string Specialty
      {
        get { return _Specialty; }
        set { _Specialty = value; OnPropertyChanged(); }
      }

      #endregion Properties Getters and Setters

      public event PropertyChangedEventHandler? PropertyChanged;
      protected void OnPropertyChanged([CallerMemberName] string name = "") =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
    }
  }
}

CodeBehind ContactWindow:

using System.Windows;

namespace WpfApp1
{
  public partial class Window005A : Window
  {
    public Window005A()
    {
      InitializeComponent();
    }
    private void Close_Click(object sender, RoutedEventArgs e)
    {
      this.DialogResult = false;
      this.Close();
    }

    private void Save_Click(object sender, RoutedEventArgs e)
    {
      this.DialogResult = true;
      this.Close();
    }
  }
}

Answer

Hi,
if you want implement mixed code (MVVM without command binding and CodeBehind) try following demo:

XAML MainWindow:

and code:

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Data;
using WpfApp005;
using WpfApp1;

namespace WpfApp1
{
  public partial class Window005 : Window
  {
    public Window005()
    {
      InitializeComponent();
    }

    private void Add_Click(object sender, RoutedEventArgs e) => 
      ((ViewModel)this.DataContext).CmdExecute("Add_Click");
    private void Edit_Click(object sender, RoutedEventArgs e) => 
      ((ViewModel)this.DataContext).CmdExecute("Edit_Click");
    private void Remove_Click(object sender, RoutedEventArgs e) => 
      ((ViewModel)this.DataContext).CmdExecute("Remove_Click");
  }
}

namespace WpfApp005
{
  public class ViewModel
  {
    AppDbContext ctx = new AppDbContext();
    public ICollectionView View
    {
      get
      {
        ctx.tblContact.Load();
        cvs.Source = ctx.tblContact.Local.ToObservableCollection();
        return cvs.View;
      }
    }
    private CollectionViewSource cvs = new CollectionViewSource();
    public ObservableCollection? ContactDetails { get; set; }

    public ContactDetail CurrentContact { get; set; }

    private Window005A addContactWindow;
    private bool? ret;

    public void CmdExecute(object parameter)
    {
      switch (parameter.ToString())
      {
        case "Add_Click":
          addContactWindow = new Window005A() { DataContext = this};
          CurrentContact = new ContactDetail();
          ret = addContactWindow.ShowDialog();
          if (ret.HasValue && ret.Value) ctx.tblContact.Add(CurrentContact);
          else CurrentContact = null;
          ctx.SaveChanges();
          break;
        case "Edit_Click":
          if (CurrentContact != null)
          {
            addContactWindow = new Window005A() { DataContext = this };
            ret = addContactWindow.ShowDialog();
            if (ret.HasValue && ret.Value) ctx.SaveChanges();
            else
            {
              ctx.Entry(CurrentContact).State = EntityState.Unchanged;
              cvs.View.Refresh();
              OnPropertyChanged(nameof(View));
            }
          }
          break;
        case "Remove_Click":
          if (CurrentContact != null) ctx.tblContact.Remove(CurrentContact);
          ctx.SaveChanges();
          break;
        default:
          break;
      }
    }

    public event PropertyChangedEventHandler? PropertyChanged;
    internal void OnPropertyChanged([CallerMemberName] string name = "") =>
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
  }

  public class AppDbContext : DbContext
  {
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) =>
      optionsBuilder.UseSqlServer(WpfApp1.Properties.Settings.Default.cnSQL);

    public DbSet tblContact { get; set; }
  }

  public class ContactDetail : INotifyPropertyChanged
  {
    #region private fields
    private string _Firstname = String.Empty;
    private string _Lastname = String.Empty;
    private string _Address = String.Empty;
    private string _Phone = String.Empty;
    private string _Email = String.Empty;
    private DateTime _Birthday = DateTime.Now;
    private string _Specialty = String.Empty;
    #endregion

    #region Properties Getters and Setters

    public int ID { get; set; }

    public string Firstname
    {
      get { return _Firstname; }
      set { _Firstname = value; OnPropertyChanged(); }
    }

    public string Lastname
    {
      get { return _Lastname; }
      set { _Lastname = value; OnPropertyChanged(); }
    }

    public string Address
    {
      get { return _Address; }
      set { _Address = value; OnPropertyChanged(); }
    }

    public string Phone
    {
      get { return _Phone; }
      set { _Phone = value; OnPropertyChanged(); }
    }

    public string Email
    {
      get { return _Email; }
      set { _Email = value; OnPropertyChanged(); }
    }
    public DateTime Birthday
    {
      get { return _Birthday; }
      set { _Birthday = value; OnPropertyChanged(); }
    }

    public string Specialty
    {
      get { return _Specialty; }
      set { _Specialty = value; OnPropertyChanged(); }
    }

    #endregion Properties Getters and Setters

    public event PropertyChangedEventHandler? PropertyChanged;
    protected void OnPropertyChanged([CallerMemberName] string name = "") =>
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
  }
}

take ContactWindows CodeBehind from my last posting.

Answer

Hi, Can you please help me move the CmdExecute method to Code Behind? It must be as follows:

ViewModel

namespace MyContacts
{
    public class ViewModel
    {
        AppDbContext ctx = new AppDbContext();
        public ICollectionView View
        {
            get
            {
                ctx.tblContact.Load();
                cvs.Source = ctx.tblContact.Local.ToObservableCollection();
                return cvs.View;
            }
        }
        private CollectionViewSource cvs = new CollectionViewSource();
        public ObservableCollection? ContactDetails { get; set; }

        public ContactDetail CurrentContact { get; set; }

        public event PropertyChangedEventHandler? PropertyChanged;
        internal void OnPropertyChanged([CallerMemberName] string name = "") =>
          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
    }


    public class AppDbContext : DbContext
    {
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) =>
          optionsBuilder.UseSqlServer(MyContacts.Properties.Settings.Default.cnSQL); \  I get an error with your code here

        public DbSet tblContact { get; set; }
    }

    public class ContactDetail : INotifyPropertyChanged
    {
        #region private fields
        private string _Firstname = String.Empty;
        private string _Lastname = String.Empty;
        private string _Address = String.Empty;
        private string _Phone = String.Empty;
        private string _Email = String.Empty;
        private DateTime _Birthday = DateTime.Now;
        private string _Specialty = String.Empty;
        #endregion

        #region Properties Getters and Setters

        public int ID { get; set; }

        public string Firstname
        {
            get { return _Firstname; }
            set { _Firstname = value; OnPropertyChanged(); }
        }

        public string Lastname
        {
            get { return _Lastname; }
            set { _Lastname = value; OnPropertyChanged(); }
        }

        public string Address
        {
            get { return _Address; }
            set { _Address = value; OnPropertyChanged(); }
        }

        public string Phone
        {
            get { return _Phone; }
            set { _Phone = value; OnPropertyChanged(); }
        }

        public string Email
        {
            get { return _Email; }
            set { _Email = value; OnPropertyChanged(); }
        }
        public DateTime Birthday
        {
            get { return _Birthday; }
            set { _Birthday = value; OnPropertyChanged(); }
        }

        public string Specialty
        {
            get { return _Specialty; }
            set { _Specialty = value; OnPropertyChanged(); }
        }

        #endregion Properties Getters and Setters

        public event PropertyChangedEventHandler? PropertyChanged;
        protected void OnPropertyChanged([CallerMemberName] string name = "") =>
          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));

    }
}

Code Behind

namespace MyContacts
{
    /// 
    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            //ViewModel.Instance.FillList();
            this.DataContext = ViewModel.Instance; 
        }

        private void Add_Click(object sender, RoutedEventArgs e)
        {
            addContactWindow = new AddContactWindow() { DataContext = this };
            CurrentContact = new ContactDetail();
            ret = addContactWindow.ShowDialog();
            if (ret.HasValue && ret.Value) ctx.tblContact.Add(CurrentContact);
            ctx.SaveChanges();
        }

        private void Edit_Click(object sender, RoutedEventArgs e)
        {
            if (CurrentContact != null)
            {
                addContactWindow = new AddContactWindow() { DataContext = this };
                ret = addContactWindow.ShowDialog();
                if (ret.HasValue && ret.Value) ctx.SaveChanges();
                else
                {
                    ctx.Entry(CurrentContact).State = EntityState.Unchanged;
                    cvs.View.Refresh();
                    OnPropertyChanged(nameof(View));
                }
            }
        }

        private void Remove_Click(object sender, RoutedEventArgs e)
        {
            if (CurrentContact != null) ctx.tblContact.Remove(CurrentContact);
            ctx.SaveChanges();
        }
    }
}

Thanks!

Answer

Hi @Peter Fleischer (former MVP) , I've got your code working now. It has a few errors. You can reproduce the error as follows:

click add button
2: Click directly Close Button(Without entering anything)
3: Click Edit Button -> AddContactWiondow will be opened (But it must not be, there is nothing in the Database or View)
click close button -> an item is entered (but this must not be the case)

When deleting this item, an error will also be displayed

How to update database automatically from ObervableCollection

5 answers