Business Apps Example for Silverlight 3 RTM and .NET RIA Services July Update: Part 14: Visual Basic (VB) and WPF Support

Article
07/29/2009

A few folks commented that they’d like to see something in my series updating my Mix09 talk “building business applications with Silverlight 3” in Visual Basic. VB is *super* important in the business application space, so I have no problem accommodating that request. By while I was at it I thought i’d also show a WPF client for RIA Services via the very cool ADO.NET Data Services support we have. This is much like the WinForms support I showed earlier.

The demo requires (all 100% free and always free):

VS2008 SP1 (Which includes Sql Express 2008)
Silverlight 3 RTM
.NET RIA Services July '09 Preview

Also, download the full demo files and, of course, check out the running application.

You can see the full series here

In Part 1: Navigation Basics there is no code whatsoever, so the VB version looks just like what I posted.

In Part 2: Rich Data Query there is some more interesting code snippets. First, let’s look at the DomainService

    1: <EnableClientAccess()> _
    2: Public Class SuperEmployeeDomainService
    3:     Inherits LinqToEntitiesDomainService(Of NORTHWNDEntities)
    4:  
    5:     Public Function GetSuperEmployees() As IQueryable(Of SuperEmployee)
    6:         Dim q = From emp In Me.Context.SuperEmployeeSet _
    7:                 Where emp.Issues > 100 _
    8:                 Order By emp.EmployeeID
    9:         Return q
   10:     End Function
   11:  
   12:  
   13:     Public Sub UpdateSuperEmployee(ByVal currentSuperEmployee As SuperEmployee)
   14:         Me.Context.AttachAsModified(currentSuperEmployee, Me.ChangeSet.GetOriginal(currentSuperEmployee))
   15:     End Sub
   16:     Public Sub InsertSuperEmployee(ByVal superEmployee As SuperEmployee)
   17:         Me.Context.AddToSuperEmployeeSet(superEmployee)
   18:     End Sub

Here we are defining the Query, Update and Insert methods.

Then to show off some of our POCO support, I created a method to return the origin counts

 Public Function GetOrigins() As IQueryable(Of Origin)
  
      Dim q = (From emp In Context.SuperEmployeeSet _
               Select emp.Origin).Distinct().Select(Function(name) New Origin With {.Name = name, .Count = Context.SuperEmployeeSet.Count(Function(emp) emp.Origin.Trim() = name.Trim())})
      q = q.Where(Function(emp) emp.Name IsNot Nothing)
      Return q
  End Function

and defined a POCO class to return that data to the client to show in my AutoComplete box

 Public Class Origin
     Public Sub New()
     End Sub
     Private _Name As String
     <Key()> _
     Public Property Name() As String
         Get
             Return _Name
         End Get
         Set(ByVal value As String)
             _Name = value
         End Set
     End Property
     Private _Count As Integer
     Public Property Count() As Integer
         Get
             Return _Count
         End Get
         Set(ByVal value As Integer)
             _Count = value
         End Set
     End Property
 End Class

On the client side in the Silverlight project I end up doing most things through binding in Xaml, so those are exactly the same in VB. But I did create a AddNewEmployee ChildWindow.

 Partial Public Class AddNewWindow
     Inherits ChildWindow
     Private _NewEmployee As SuperEmployee
     Public Property NewEmployee() As SuperEmployee
         Get
             Return _NewEmployee
         End Get
         Set(ByVal value As SuperEmployee)
             _NewEmployee = value
         End Set
     End Property
  
     Public Sub New()
         InitializeComponent()
  
         NewEmployee = New SuperEmployee()
         NewEmployee.LastEdit = DateTime.Now.[Date]
         Me.newEmployeeForm.CurrentItem = NewEmployee
     End Sub
  
     Private Sub OKButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
         newEmployeeForm.CommitEdit()
         Me.DialogResult = True
     End Sub
  
     Private Sub CancelButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
         Me.DialogResult = False
     End Sub
  
 End Class

And then we just raise this event

 Private Sub AddNew_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
     Dim w = New AddNewWindow()
  
     AddHandler w.Closed, AddressOf addNewWindow_Closed
  
     w.Show()
  
 End Sub
  
 Private Sub addNewWindow_Closed(ByVal sender As Object, ByVal e As EventArgs)
     Dim win = TryCast(sender, AddNewWindow)
     Dim context = TryCast(dds.DomainContext, SuperEmployeeDomainContext)
     If win.DialogResult = True Then
         context.SuperEmployees.Add(win.NewEmployee)
     End If
 End Sub

Part 3: Authentication – No code whatsoever here… This is exactly the same between VB and C#.

Part 4: SEO, Export to Excel and Out of Browser

For SEO, we enabled deeplinking by handing a couple of events…

 'Executes when the user navigates to this page.
 Protected Overrides Sub OnNavigatedTo(ByVal e As System.Windows.Navigation.NavigationEventArgs)
     Dim qs = NavigationContext.QueryString
  
     If qs.ContainsKey("EmpId") Then
         dds.FilterDescriptors.Add(New FilterDescriptor("EmployeeID", FilterOperator.IsEqualTo, qs("EmpId")))
     End If
  
 End Sub

and

 Private Sub dataGrid1_SelectionChanged(ByVal sender As System.Object, ByVal e As System.Windows.Controls.SelectionChangedEventArgs)
     Dim emp = TryCast(dataGrid1.SelectedItem, SuperEmployee)
     If emp IsNot Nothing Then
         PermalinkTextBox.Text = (Application.Current.Host.Source.ToString().Replace("ClientBin/MyApp.xap", "") & "#/Home?EmpId=") & emp.EmployeeID
     End If
 End Sub

The server side code for Sitemap.aspx and the alternate content in default.aspx is identical.. expect for a small bit of URL rewritting code in default.aspx to ensure both the server and client have access to the deep link.

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
  
     Dim empId As String = Request.QueryString("EmpId")
     Dim deepLink = "/Home?EmpId=" & empId
  
     If empId IsNot Nothing Then
         Response.Write("<script type=text/javascript>window.location.hash='#" & deepLink & "';</script>")
     End If
  
 End Sub

The bit about exporting to Excel is super easy as well..

 Private Sub ExportToExcel_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
     Dim context = TryCast(dds.DomainContext, SuperEmployeeDomainContext)
     Dim s = Application.GetResourceStream(New Uri("excelTemplate.txt", UriKind.Relative))
     Dim dialog = New SaveFileDialog()
  
     dialog.DefaultExt = "*.xml"
     dialog.Filter = "Excel Xml (*.xml)|*.xml|All files (*.*)|*.*"
  
     If dialog.ShowDialog() = False Then
         Exit Sub
     End If
  
     Using sw = New StreamWriter(dialog.OpenFile())
         Dim sr = New StreamReader(s.Stream)
         While Not sr.EndOfStream
             Dim line = sr.ReadLine()
             If line = "***" Then
                 Exit While
             End If
             sw.WriteLine(line)
         End While
  
         For Each emp In context.SuperEmployees
             sw.WriteLine("<Row>")
             sw.WriteLine("<Cell><Data ss:Type=""String"">{0}</Data></Cell>", emp.Name)
             sw.WriteLine("<Cell><Data ss:Type=""String"">{0}</Data></Cell>", emp.Origin)
             sw.WriteLine("<Cell><Data ss:Type=""String"">{0}</Data></Cell>", emp.Publishers)
             sw.WriteLine("<Cell><Data ss:Type=""Number"">{0}</Data></Cell>", emp.Issues)
             sw.WriteLine("</Row>")
         Next
         While Not sr.EndOfStream
             sw.WriteLine(sr.ReadLine())
         End While
     End Using
 End Sub

After a bit of formatting… we get:

Finally, in Part 5: Astoria, Add Service Reference and WinForms… Defining the ADO.NET Data Services in the web project looks like:

 Public Class SuperEmployeeWebDataService
  
     Inherits DataService(Of [SuperEmployeeDomainService])
     Implements IServiceProvider
  
     ' This method is called only once to initialize service-wide policies.
     Public Shared Sub InitializeService(ByVal config As IDataServiceConfiguration)
         ' TODO: set rules to indicate which entity sets and service operations are visible, updatable, etc.
         ' Examples:
         config.SetEntitySetAccessRule("*", EntitySetRights.All)
         config.SetServiceOperationAccessRule("*", ServiceOperationRights.All)
     End Sub

Then for some variety, I created a WPF client for this service. I also made use of the DataGrid control from the very cool WPF Control Toollit

first I load the data…

 Private Sub LoadButton_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles LoadButton.Click
     Context = New SuperEmployeeDomainService( _
         New Uri("https://localhost:4558/SuperEmployeeWebDataService.svc/"))
     Context.MergeOption = MergeOption.AppendOnly
  
     Dim q = From emp In Context.SuperEmployee _
     Where emp.Issues > 10 _
     Order By emp.Name _
     Select emp
  
     Dim savedCursor = Cursor
     Cursor = Cursors.Wait
     Me.DataGrid1.ItemsSource = q.ToList()
     Cursor = savedCursor
 End Sub

Then update whenever there is a change.

 Private Sub DataGrid1_CurrentCellChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
     Dim selectedItem As SuperEmployee = Me.DataGrid1.CurrentItem
  
     If selectedItem Is Nothing Then
         Return
     End If
  
     Dim q = From emp In Context.SuperEmployee _
                 Where emp.EmployeeID = selectedItem.EmployeeID _
                 Select emp
     Dim employee = q.FirstOrDefault()
  
     employee.Gender = selectedItem.Gender
     employee.Issues = selectedItem.Issues
     employee.LastEdit = selectedItem.LastEdit
     employee.Name = selectedItem.Name
     employee.Origin = selectedItem.Origin
     employee.Publishers = selectedItem.Publishers
     employee.Sites = selectedItem.Sites
  
     Context.UpdateObject(employee)
  
     Dim savedCursor = Cursor
     Cursor = Cursors.Wait
  
     Context.SaveChanges()
  
     Cursor = savedCursor
  
 End Sub

Business Apps Example for Silverlight 3 RTM and .NET RIA Services July Update: Part 14: Visual Basic (VB) and WPF Support

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