Silverlight 3 combobox selectedvalue

by Andrei Hetel 25. July 2011 05:22

I was very unpleasant surprised to find out that there is no selectedvalue property for a combobox in Silverlight 3. Most of the time you want to perform an action based on a combo box selection change. So, I come up with a simple solution which will be detailed below.

 

XAML code:

<ComboBox x:Name="MyColors">

 

We need two simple classes to bind the combobox:

 

Public Class CComboItem

     Private _ID As Int64
     Private _Description As String

     Public Sub New(ByVal pid As Int64, ByVal pDesc As String)
         _ID = pid
         _Description = pDesc
     End Sub

     Public Property ID() As Int64
         Get
             Return _ID
         End Get
         Set(ByVal value As Int64)
             _ID = value
         End Set
     End Property

     Public Property Description() As String
         Get
             Return _Description
         End Get
         Set(ByVal value As String)
             _Description = value
         End Set
     End Property

End Class

 

Second class, more exactly a collection:

 

Imports System.Collections.ObjectModel

Public Class CComboList
     Inherits ObservableCollection(Of CComboItem)

     Public Sub addItem(ByVal itm As CComboItem)
         Add(itm)
     End Sub
End Class

 

Load the combo as follows:

 

Dim colorList As New CComboList
colorList.Add(New CComboItem(1, "red"))
colorList.Add(New CComboItem(2, "yellow"))
colorList.Add(New CComboItem(3, "blue"))
MyColors.ItemsSource = colorList
MyColors.DisplayMemberPath = "Description"
MyColors.SelectedIndex = 0

 

Finally, because the post is already too long, get selected value from the combo box:

 

Private Sub MyColors_SelectionChanged(ByVal sender As Object, ByVal e As System.Windows.Controls.SelectionChangedEventArgs) Handles MyColors.SelectionChanged
     Dim id As Int64
     If MyColors.SelectedItem Is Nothing Then Exit Sub
     ' here is the selected value...
     id = DirectCast(MyColors.SelectedItem, CComboItem).ID
End Sub

 

Pretty simple, but at least is doing the trick.

 

Category: .NET, VB.NET, Silverlight
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Facebook - how to run a FQL query

by Andrei Hetel 12. December 2009 16:17

Better think twice before starting a Facebook application using AP.NET - it's PHP world there. That could change in the future because I could see some C# example in Facebook wiki, which is a big step forward I suppose. More than this, in the glorious day when I finally manage to integrate some Facebook functionality into Ysabel, Facebook Developer Toolkit released version 3.0 (all my code is based on 2.0 - and people are complaining about backward compatibility) - that really made my day!

According with the pages that I read about ASP.NET and Facebook it's best to choose an IFRAME application type and use master pages. Not 100% if it's the best strategy, but this is what I've done.

Anyway, it took me a couple of hours to figure out how to run a FQL query, and after that to do something with the result, but it's finally working. I was surprised that only couple of lines of code are needed.

A working piece of code looks like this:

 

Dim fbAPI As new facebook.API
Dim query As String
Dim xmlDR As String
Dim ds As DataSet

fbAPI.ApplicationKey = "your application key"
fbAPI.Secret = "your secret key"

query = "select uid, name from user where uid in (select uid2 from friend where uid1=" & your_Facebook ID & ")"

xmlDR = fbAPI.fql.query(query)
ds = New DataSet()
ds.ReadXml(New StringReader(xmlDR), XmlReadMode.InferSchema)

Dataset returned contains 2 datatables, in the second datatable is the data you have requested (complete list of your friends according to the above query).

Simple isn't it? Happy coding.

 

Category: Facebook, .NET, ASP.NET
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Web services - returning custom objects

by Andrei Hetel 13. November 2008 14:12

This article is focused on web services, more exactly about the way you can return a custom object into your client application (in my case a windows mobile application). The easiest way is to use a simple example. On web service project let's create a simple class with only 2 properties CastleId, CastleName:

 

<Serializable()> _
Public Class CCastle

  Private _CastleId As Int64
  Private _CastleName As String

  Public Sub New()
  End Sub
  Public Sub New(ByVal newCastleId As Int64, ByVal newCastleName As String)
    _CastleId = newCastleId
    _CastleName = newCastleName
  End Sub

  Public Property CastleId() As Int64
    Get
      Return _CastleId
    End Get
    Set(ByVal value As Int64)
      _CastleId = value
    End Set
  End Property
  Public Property CastleName() As String
    Get
      Return _CastleName.Trim
    End Get
    Set(ByVal value As String)
      _CastleName = value
    End Set
  End Property

End Class

 

Please note that the class is marked as serializable and the properties are public read/write, to be able to use it into the client application created later.

Now, let's create a collection class, also serializable:

 

<Serializable()> _
Public Class CCastleList
  Private _CastleList As List(Of CCastle)

  Public Property CastleList() As List(Of CCastle)
    Get
      Return _CastleList
    End Get
    Set(ByVal value As List(Of CCastle))
      _CastleList = value
    End Set
  End Property
End Class

 

Finally, web method:

 

<WebMethod()> _
Public Function CastleList() As CCastleList

  Dim cl As New CCastleList
  Dim myList As New List(Of CCastle)

  myList.Add(New CCastle(1, "Castle1"))
  myList.Add(New CCastle(2, "Castle2"))
  cl.CastleList = myList
  Return cl

End Function

 

That's all on the web service side. Now, let's create a client application, reference the web service and call the web method. Like this:

 

Public Sub LoadCastleList()

  Dim ws As localhost.YsaMain
  Dim cl As localhost.CCastleList
  Dim castle As localhost.CCastle

  Try
    ws = New localhost.YsaMain
    cl = ws.CastleList()

    For Each castle In cl.CastleList
      debug.writeline (castle.CastleId & " " & castle.CastleName)
    Next castle

  Catch ex As Exception
  End Try
End Sub

 

Category: ASP.NET, .NET, VB.NET
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.NET Code Profiler

by Andrei Hetel 6. November 2008 04:28

Have you ever dream to see how well your .NET code is performing? Yes, I do. Today I find it here: .NET Profiler - looks pretty well and on top of this it's free. Check video demonstration available on their site and review your code. Good luck!

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SQL Server 2005 CLR Integration

by Andrei Hetel 6. August 2008 10:25

There are a lot of articles on the net about how to achieve this, some of them good, some other hard to follow. My problem was pretty simple: scan a folder from new files, import and process them and at the end move them some place else.

 

There are 2 approaches:

  • First is to use FSO and OLE Automation
  • Second CLR integration

 

I decide to implement the second solution because:
  • is very hard to work with OLE automation
  • if the COM object executes in SQL Server address space, a bug in your code will crash SQL Server

 

VB.NET code
Imports System.IO
Imports System.Security.Permissions

<IODescriptionAttribute("SQLServerFileSystemWatcherDesc")> _
<PermissionSetAttribute(SecurityAction.InheritanceDemand, Name:="FullTrust")> _
<PermissionSetAttribute(SecurityAction.LinkDemand, Name:="FullTrust")> _

Public Class Import
<PermissionSet(SecurityAction.Demand, Name:="FullTrust")> _
<Microsoft.SqlServer.Server.SqlProcedure()> _
Public Shared Sub Arhive(ByVal sourcePath As String, ByVal fname As String, ByVal destPath As String)
File.Move(finalSource & fname, finalDest & fname)
End Sub
End Class
Code is compiled like this from command prompt:
vbc /t:library CAMAImport.vb

 

SQL Server side

 

Steps:
1) Enable CLR integration:

 

EXEC sp_configure @configname = 'clr enabled', @configvalue = 1
RECONFIGURE WITH OVERRIDE
GO

 

2)Register the assembly (please note PERMISSION_SET = EXTERNAL_ACCESS will never work wih SAFE! - took me an hour to figure out this):

 

CREATE ASSEMBLY WDMImport FROM 'c:\SQLServer\WDMLog\Import.dll'
WITH PERMISSION_SET = EXTERNAL_ACCESS
GO

 

3) Tell database server where to find the object code:

 

CREATE PROC ImportMoveFile
(@sourcePath NVARCHAR(255), @fname NVARCHAR(255), @destPath NVARCHAR(255) )
AS EXTERNAL NAME WDMImport.Import.Arhive
GO

 

4) Run it:

 

EXEC ImportMoveFile 'c:\', 'test.txt', 'c:\Imported\'

 

Category: .NET, SQL Server, VB.NET, CLR
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