我有一个发票表，我像这样加载数据（并且运行良好）：

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

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

视图模型：

_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;

        }

现在，我想做的是，每当我填写某个表单（将其插入到数据库表中）时，都要更新和刷新这个ObservableCollection。我有一个按钮来执行此操作：

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

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

DataGrid变空...但由于某种原因无法再次重新加载。您对可能的原因有什么想法吗？这是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>

正如我之前所说的，ObservableCollection在我第一次运行应用程序时工作，只是在我刷新它时不工作。