Binding not writing to datasource on .NET Compact Framework Form -- works on Full Framework
- by Dave Welling
I have a problem with a bound user control writing back to it's datasource on a NetCF forms application. The application is too complex to post code, so I made a toy version to show you.
I create a form, usercontrol with a combobox, a class (testBind) and another class (TestLookup).
I bind a property of the usercontrol ("value") to a property ("selectedValue") on the testBind class. The testBind class implements INotifyPropertyChanged.
I create a few fascade methods on the user control to bind the contained combobox to a BindingList(of TestLookup).
I create a button to show the value of the testBind bound property (in a MessageBox).
The messagebox returns "-1" every time regardless of the combobox entry selected. I can take the EXACT same code, paste it in a full framework Forms app and it will return the correct value of the selected combobox entry.
Imports System.ComponentModel
Public Class Form2
Inherits Form
Private _testBind1 As testBind
Private _testUserControlX As UserControlX
Friend WithEvents _buttonX As System.Windows.Forms.Button
Public Sub New()
_buttonX = New System.Windows.Forms.Button
_buttonX.Location = New System.Drawing.Point(126, 228)
_buttonX.Size = New System.Drawing.Size(70, 21)
_testBind1 = New testBind
_testUserControlX = New UserControlX()
Dim _lookup As New System.ComponentModel.BindingList(Of TestLookup)()
_lookup.Add(New TestLookup(1, "text1"))
_lookup.Add(New TestLookup(2, "text2"))
_testUserControlX.DataSource = _lookup
_testUserControlX.DisplayMember = "Text"
_testUserControlX.ValueMember = "ID"
_testUserControlX.DataBindings.Add("Value", _testBind1, "SelectedID", False, DataSourceUpdateMode.OnValidation)
MinimizeBox = False
Controls.Add(_testUserControlX)
Controls.Add(_buttonX)
End Sub
Private Sub ButtonX_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles _buttonX.Click
MessageBox.Show(_testBind1.SelectedID.ToString())
End Sub
Public Class testBind
Implements System.ComponentModel.INotifyPropertyChanged
Private _selectedRow As Integer = -1
Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
Protected Sub OnPropertyChanged(ByVal PropertyName As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(PropertyName))
End Sub
Public Property SelectedID() As Integer
Get
Return _selectedRow
End Get
Set(ByVal value As Integer)
_selectedRow = value
OnPropertyChanged("SelectedID")
End Set
End Property
End Class
Public Class TestLookup
Private _text As String
Private _id As Integer
Public Sub New(ByVal id As Integer, ByVal text As String)
_text = text
_id = id
End Sub
Public Property ID() As Integer
Get
Return _id
End Get
Set(ByVal value As Integer)
_id = value
End Set
End Property
Public Property Text() As String
Get
Return _text
End Get
Set(ByVal value As String)
_text = value
End Set
End Property
End Class
End Class
Public Class UserControlX
Inherits System.Windows.Forms.UserControl
Friend WithEvents ComboBox1 As System.Windows.Forms.ComboBox
Public Sub New()
Me.ComboBox1 = New System.Windows.Forms.ComboBox
Me.Controls.Add(Me.ComboBox1)
End Sub
Public Property Value() As Integer
Get
Return ComboBox1.SelectedValue
End Get
Set(ByVal value As Integer)
ComboBox1.SelectedValue = value
End Set
End Property
Public Property DataSource() As Object
Get
Return ComboBox1.DataSource
End Get
Set(ByVal value As Object)
ComboBox1.DataSource = value
End Set
End Property
Public Property ValueMember() As String
Get
Return ComboBox1.ValueMember
End Get
Set(ByVal value As String)
ComboBox1.ValueMember = value
End Set
End Property
Public Property DisplayMember() As String
Get
Return ComboBox1.DisplayMember
End Get
Set(ByVal value As String)
ComboBox1.DisplayMember = value
End Set
End Property
End Class
