Problems with Entity Famework and bindingsources

[desanti]

Hello ! i'm using vb.net 2017 with EF 6 I have 2 tables on my database : Product and ProductDetail I have also 2 bindingsource Productbindingsource and ProductDetailsbindingsource. I have also 2 datagridview each of them bound to the respective bindingsource. When the user select a product in the first datagridview , the other datagridview is filled with Productdetails for the selected product. I have this code :

Private sub Fill_Product
context.Products.Where(Function(t2) t2.cl>5).Load
ProductBindingsource.datasource=context.Products.Local.ToBindinglist
End sub

Private Sub ProductBindingSource_CurrentChanged(sender As Object, e As EventArgs) Handles ProductBindingSource.CurrentChanged

context.Entry(ProductBindingSource.Current).Collection("ProductDetails").Load()
ProductDetailsBindingsource.Datasource=DirectCast(ProductBindingSource.Current, Product).ProductDetails
End sub

Private Sub RollBack()
Dim changedEntries = context.ChangeTracker.Entries().Where(Function(x) x.State <> EntityState.Unchanged).ToList()
For Each entry In changedEntries

    Select Case entry.State
        Case EntityState.Modified
            entry.CurrentValues.SetValues(entry.OriginalValues)
            entry.State = EntityState.Unchanged
        Case EntityState.Added
            entry.State = EntityState.Detached
        Case EntityState.Deleted
            entry.State = EntityState.Unchanged
    End Select
Next

End Sub

I have 2 problems with this code : 1.when I delete a ProductDetail from the second Grid , and after execute the rollback Sub , the deleted ProductDetail is not back on that datagrid , andalso when I add new Productdetail when I rollback this is not removed from the gridview.( other modifications in values , are reverted to original values). 2.On the sub ProductBindingSource_CurrentChanged , everytime that the user select a product in the first grid , the second grid is filled with ProductDetails and database is queried with .Load. But this is ok when the user select a Product for the first time . What about when the user select a Product for the second or third time ? The product Details are already loaded , so what to do to not query again from database but use local data ? Thank you !