private void SaveButton_Click(object sender, RoutedEventArgs e)
{
// When you delete an object from the related entities collection
// (in this case Products), the Entity Framework doesn’t mark
// these child entities as deleted.
// Instead, it removes the relationship between the parent and the child
// by setting the parent reference to null.
// So we manually have to delete the products
// that have a Category reference set to null.
// The following code uses LINQ to Objects
// against the Local collection of Products.
// The ToList call is required because otherwise the collection will be modified
// by the Remove call while it is being enumerated.
// In most other situations you can use LINQ to Objects directly
// against the Local property without using ToList first.
foreach (var item in _context.Products.Local.ToList())
{
if (item.ProductName == string.Empty)
{
_context.Products.Remove(item);
}
}
_context.SaveChanges();
// Refresh the grids so the database generated values show up.
this.ProductDataGrid.Items.Refresh();
}
