I have an invoice table, I'm loading the data like this (and it's working fine):

  private ObservableCollection<InvoiceData> _listAchats;
    public ObservableCollection<InvoiceData> ListAchats
    {
        get { return _listAchats; }

        set
        {
            _listAchats = value;
            NotifyPropertyChanged("ListAchats");
           
        }
    }

ViewModel:

_listAchats = new ObservableCollection<InvoiceData>();
ListAchats = GetAchatList();

   public ObservableCollection<InvoiceData> GetAchatList()
        {
            //Count = 0;

            ObservableCollection<InvoiceData> ClientsList = new ObservableCollection<InvoiceData>();

            using (SQLiteConnection conn =
                new SQLiteConnection(ConfigurationManager.ConnectionStrings["StringConnexion"].ConnectionString))
            {
                conn.Open();

                SQLiteCommand cmdNotes =
                    new SQLiteCommand("SELECT * FROM Invoice", conn);
                //   cmdNotes.Parameters.AddWithValue("@MAT_EMP", Matricule);

                using (SQLiteDataReader reader = cmdNotes.ExecuteReader())
                {

                    var ordinals = new
                    {
                        InvoiceId = reader.GetOrdinal("invoice_id"),
                        SellerName = reader.GetOrdinal("seller_name"),
                        PurchaseDate = reader.GetOrdinal("purchase_date")

                    };



                    while (reader.Read())
                    {

                        var temp = new TableInvoice();

                        temp.IdInvoice = reader.GetInt32(ordinals.InvoiceId);
                        temp.SellerName = reader.GetString(ordinals.SellerName);
                        temp.PurchaseDate = reader.GetDateTime(ordinals.PurchaseDate).ToShortDateString();
                      

                  //      temp.JoinDateString = RelativeTime.ConvertDate(reader.GetDateTime(ordinals.JoinDate));



                        ClientsList.Add(temp.ClientsList());
                    }
                }
            }

            return ClientsList;


        }

Now, what I want to do is that whenever I fill a certain form (insert it into a database table) is to update and refresh this ObservableCollection. I have a button doing this:

  private void Refresh()
    {
        Console.WriteLine("This is triggered");

        ListAchats.Clear();
        ListAchats = GetAchatList();
        Console.WriteLine(ListAchats.Count);
    }

The DataGrid, goes empty... but never reload again for some reason. Any thoughts on what could the reason be? This is the XAML:

<DataGrid Margin="0 16 0 0"
          Name="Agrid"
          Background="Transparent"
          ScrollViewer.CanContentScroll="True" 
          ScrollViewer.VerticalScrollBarVisibility="Auto"
          AutoGenerateColumns="False"
          Focusable="False"
          MaxHeight="400"
          ScrollViewer.HorizontalScrollBarVisibility="Auto"
          CanUserSortColumns="True"
          SelectedItem="{Binding SelectedAchat}"
          ItemsSource="{Binding ListAchats,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
          CanUserAddRows="False"
          IsReadOnly="True" SelectionMode="Single" SelectionUnit="FullRow">
    <DataGrid.InputBindings>
        <KeyBinding Key="Delete" Command="{Binding DeleteButtonCommand}"/>
    </DataGrid.InputBindings>
    <DataGrid.Columns>
        <DataGridTemplateColumn SortMemberPath="IdInvoice"  Header="N° Achat">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock VerticalAlignment="Center"
                               Text="{Binding Path=IdInvoice, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>

        <DataGridTemplateColumn  SortMemberPath="SellerName" Header="Nom de vendeur" >
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock VerticalAlignment="Center"
                                Text="{Binding Path=SellerName, Mode=TwoWay}" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>


        <DataGridTemplateColumn SortMemberPath="PurchaseDate"  Header="Date d'achat" >
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock VerticalAlignment="Center"
                               Text="{Binding Path=PurchaseDate, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>

Like I previously said, the ObservableCollection works the first time I run the app, just not when I refresh it.

CodePudding user response：

From your explanation, I dare to assume that you have something wrong with the change notification.
Try this implementation:

    // "ReadOnly" propery
    public ObservableCollection<InvoiceData> ListAchats {get;} = new();

   public IEnumerable<InvoiceData> GetAchatList()
   {
       List<InvoiceData> clientsList = new List<InvoiceData>();

       // Some Code

       // When returning a list, just in case,
       // we protect the original list from changes.
       return clientsList.Select(cl => cl);
   }

    private void Refresh()
    {
        Console.WriteLine("This is triggered");

        ListAchats.Clear();

        foreach(var cl in GetAchatList())
            ListAchats.Add(cl);

        Console.WriteLine(ListAchats.Count);
    }

CodePudding user response：

Apparently, I forgot to add INotifyPropertyChanged interface to my ViewModel. That's what caused the issue.