Combo-box data binding to a class property.

Question

Hey Guys, 

I have a combo-box which has a data table as its data source.  The combo box is also bound to a class property, because every time the combo's selected value changes, I would want my class's property to reflect this change. This works fine. However, my goal is, whenever I set my classes's property, I would like my combo box to reflect that change too. This link seems to be broken. 

Here is a sample code snippet

Private _suburbdatasource As BindingSource

    Public Property SuburbDataSource As IList
        Get
            Return _suburbdatasource
        End Get
        Set(ByVal value As IList)
            Select Case True
                Case value.GetType.Name.StartsWith("LinqDataView")
                    With Me.ComboBox1
                        .DataSource = value
                        .ValueMember = "ID"
                        .DisplayMember = "Suburb"
                    End With
            End Select
        End Set
    End Property

    Public Function CreateSuburbData() As DataTable
        Dim Suburbs As DataTable = New System.Data.DataTable()

        Suburbs.Columns.Add("ID", System.Type.GetType("System.Int32"))
        Suburbs.Columns.Add("Suburb", System.Type.GetType("System.String"))
        Suburbs.Columns.Add("State", System.Type.GetType("System.String"))
        Suburbs.Columns.Add("Postcode", System.Type.GetType("System.String"))

        Suburbs.Rows.Add(1, "Essendon", "VIC", "3040")
        Suburbs.Rows.Add(2, "NorthRyde", "NSW", "2122")
        Suburbs.Rows.Add(3, "Chatswood", "NSW", "2124")
        Suburbs.Rows.Add(4, "Cheltanham", "NSW", "2523")
        Suburbs.Rows.Add(5, "Hornsby", "NSW", "3212")
        Suburbs.Rows.Add(6, "Gladesville", "VIC", "6543")
        Suburbs.Rows.Add(7, ".", ".", ".")

        Return Suburbs
    End Function

    Private Sub PopulateCombo()
        Dim mydatatable As DataTable = CreateSuburbData()
        Me.SuburbDataSource = mydatatable.AsDataView
    End Sub

    Private Sub JanusForm_Shown(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Shown
       
        PopulateCombo()
       
        Dim suburb As SuburbClass = New SuburbClass
        Me.ComboBox1.DataBindings.Add("SelectedValue", suburb, "MySuburb", True, DataSourceUpdateMode.OnPropertyChanged)

        'The below line displays the correct record i.e Cheltanham in the combo box.
        'Also when the below line executes, suburb.MySuburb has the value Cheltanham
        Me.ComboBox1.SelectedValue = 4

        'Since the combo box is data bound, I would except that when the below line executes, 
        'Me.ComboBox1.SelectedValue is set to 4 and the data that the combobox displays is Cheltanham. But none of those things happen here.
        suburb.MySuburb = 4
               
    End Sub

Public Class SuburbClass
    Implements INotifyPropertyChanged

    Private suburb As Integer

    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Public Property MySuburb As Integer
        Get
            Return Me.suburb
        End Get
        Set(ByVal value As Integer)
            Me.suburb = value
            RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(MySuburb))
        End Set
    End Property

    Protected Sub OnPropertyChanged(ByVal name As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(name))
    End Sub
End Class

I know this should be relatively simple, abut I just cant get my head around this issue. Any help will be appreciated.

Thanks

Lavanya

Answer 1

Hi lavanya,

Welcome to the MSDN forum.

You can solve your issue just change:

RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(MySuburb))

To :

RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("MySuburb"))

The property name needs to be a string type.

Hope this helps.

---

Mark Liu-lxf [MSFT]
MSDN Community Support | Feedback to us

Answer 2

Aaahhhh, yes obviously. Thanks so much for that Mark Liu-lxf.

Regards,

Laavanya