Refreshing the datagrid

Question

I have a basic SL example with several buttons (btn_Customers, btn_Products etc) and a single datagrid.

Each button is similarly setup but only the first click results in data showing in the datagrid.

The typical coding is as follows:

'in MainPage.xaml.vb

Private Sub svc_GetCustomersCompleted(sender As Object, e As SL_Enabled_WCFServiceReference.GetCustomersCompletedEventArgs) Handles svc.GetCustomersCompleted
        dg.ItemsSource = e.Result
        dg.Visibility = Windows.Visibility.Visible
End Sub

Private Sub btnLoad_Customers_Click(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs)
        
        svc.GetCustomersAsync()
        svc.CloseAsync()
End Sub

Private Sub btnLoad_Products_Click(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs)
       
        svc.GetProductsAsync()
        svc.CloseAsync()
End Sub

***********************************

 ' part of code in the service

<OperationContract()>
    Public Function GetCustomers() As List(Of Customer)
        Dim db As New NorthwindDataContext
        Return db.Customers.ToList()
    End Function

etc.....

***********************************

Question 1:

How do I refresh the datagrid to allow any sequence of datapresentations rather than just the first choice clicked?

Question 2:

I'm using Linq to SQL and wondering what is syntax to get a customised list of data rather than all the data of the table?

Sorry for such a long question(s).  Any help appreciated.

Answer 1

Hi,

First, where is your svc_GetProductsCompleted?

Second, you should set the ItemsSource to null and then set to the real result.

dg.ItemsSource = Empty
dg.ItemsSource = e.Result
dg.Visibility = Windows.Visibility.Visible

I'm using Linq to SQL and wondering what is syntax to get a customised list of data rather than all the data of the table?

For this problem, I think you need to get start from this document:

http://www.silverlight.net/learn/advanced-techniques/wcf-ria-services/get-started-with-wcf-ria-services

 

Answer 2

Thanks Jerry.... svc_GetProductsCompleted exists (I didn't want to get too verbose).

The idea of setting dg to null (dg.ItemsSource = Nothing) didn't change the behaviour of the datagrid.  Namely, once the datagrid gets populated that is it.  The next button click clears it but nothing new appears.  Any ideas?  Thanks

<code>

 Private Sub svc_GetCategoriesCompleted(sender As Object, e As DataServiceReference.GetCategoriesCompletedEventArgs) Handles svc.GetCategoriesCompleted
        dg.ItemsSource = Nothing
        dg.ItemsSource = e.Result
        dg.Visibility = Windows.Visibility.Visible
    End Sub
    Private Sub svc_GetProductsCompleted(sender As Object, e As DataServiceReference.GetProductsCompletedEventArgs) Handles svc.GetProductsCompleted
        dg.ItemsSource = Nothing
        dg.ItemsSource = e.Result
        dg.Visibility = Windows.Visibility.Visible
    End Sub
    Private Sub btn_Product_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles btn_Product.Click
        svc.GetProductsAsync()
        svc.CloseAsync()
    End Sub
    Private Sub btn_Category_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles btn_Category.Click
        svc.GetCategoriesAsync()
        svc.CloseAsync()
    End Sub

</code>