WPF实体框架绑定

Question

I'm following this tutorial and trying to implement Data Binding using an Editable ComboBox instead of the DataGrid demonstrated in the tutorial.
The only problem I encounter is that I cannot add a new item to the DB that way.
This is how I load the data:

    private DbEntities db = new DbEntities();
    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        CollectionViewSource productViewSource =
            ((CollectionViewSource)(this.FindResource("productViewSource")));

        db.Product.Load();

        productViewSource.Source = db.Product.Local;
    }

and in a Button_Click event I tried the following methods without success:

    db.Product.Add(new Product() { ProductCode = "", Description = "" });
    db.Product.Load();
    productViewSource.Source = db.Product.Local;
    productComboBox.Items.Refresh();
    productViewSource.View.MoveCurrentToLast();

and:

    ListCollectionView lcv = productComboBox.ItemsSource as ListCollectionView;
    lcv.AddNewItem(new Product() { ProductCode = "", Description = "" });
    lcv.MoveCurrentToLast();

Using the DataGrid provided by the default DataSource template works as expected by adding a new item on the empty bottom row of the grid.
Please advise.

Answer 1

You don't seem to be calling SaveChanges on your data context object anywhere. I would have thought that your code should look more like this:

db.Product.Add(new Product() { ProductCode = "", Description = "" });
db.SaveChanges();

Please see the Add/Attach and Entity States page on MSDN for more help with adding entities in the Entity Framework.