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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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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):

  1. VS2008 SP1 (Which includes Sql Express 2008)
  2. Silverlight 3 RTM
  3. .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

image

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

image

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

image_thumb[100]

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

image_thumb[98]

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

image

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

image

Comments

  • Anonymous
    July 29, 2009
    Very Great Article. I like it. I will try this style in my next project. Keep it up.

  • Anonymous
    July 29, 2009
    Excellent Series Of Articles Please How to integrate Silverlight Controls With ASP.Net MVC ?

  • Anonymous
    July 30, 2009
    The comment has been removed

  • Anonymous
    July 30, 2009
    Bell -- i am not sure.. do you have the WPF Toolkit installed? http://www.codeplex.com/wpf

  • Anonymous
    July 30, 2009
    The comment has been removed

  • Anonymous
    July 30, 2009
    The WPF Toolkit fixed the project errors, thanks. Any quick way to workaround the db issue? I'm not eager to install sql 2008 express just for this app.

  • Anonymous
    July 30, 2009
    Sure -- you could use the in memory data scenario I describe here.. http://blogs.msdn.com/brada/archive/2009/07/22/business-apps-example-for-silverlight-3-rtm-and-net-ria-services-july-update-part-6-poco-and-authentication-provider.aspx I didn't port it to VB, but it shouldn't be too hard to pull over..

  • Anonymous
    July 30, 2009
    Isn't is strange that while the sln will build, when the app is run, and after the db error, there are 52 errors? They go away if I rebuild, at least till the app tries to run again...but isn't that kind of weird?

  • Anonymous
    July 31, 2009
    The comment has been removed

  • Anonymous
    August 02, 2009
    William Bartholomew  - thanks!  We will get that fixed.