Question

Databinding combobox selection to label

Asked by: running32

I am trying to bind the combobox value member to a label but I keep getting the error  below when I get to line Me.Label31.DataBindings.Add("Text", mhcppro, "lngContactid").  There are row in the dataset.  Can someone please tell me where I am going wrong.  Thank you

An unhandled exception of type 'System.NullReferenceException' occurred in system.dll
Additional information: Object reference not set to an instance of an object

Private Sub comboTest_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles comboTest.MouseDown
        If fillpre = True Then
         
           Dim mhcppro As New DataView(DsPAPresciptionby211.tblContact)
            comboTest.DataSource = mhcppro
            comboTest.DisplayMember = "name"
            Me.Label31.DataBindings.Clear()
            Me.Label31.DataBindings.Add("Text", mhcppro, "lngContactid")
            SqlParametersDB.Name.contactid = Label31.Text
                fillpre = False
        End If
        If comboTest.Text <> "" Then
            comboTest.DroppedDown = True
        End If

                                  
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Asked On
2009-09-02 at 11:20:01ID24702281
Topic

Microsoft Visual Basic.Net

Participating Experts
3
Points
500
Comments
3

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Answers

 

by: ProtuhjPosted on 2009-09-02 at 11:24:57ID: 25244001

Why don't you just add an event handler for one of the ComboBox's events (SelectedIndexChanged or SelectedValueChanged) and then set the label's text in that event?

 

by: daffyduck14milPosted on 2009-09-02 at 13:57:46ID: 25245628

Hi,

Try to use this:
Dim mhcppro As DataView = DsPAPresciptionby211.tblContact.DefaultView()

The way you do it now adds the table to the dataview. Given that you do not want any sorting, filtering or other exotic methods it is easier to grab the default view from the table object.

Using DataBindings in this way is a valid approach. In some cases I would agree with Protuhj, if you need additional processing based on the selected value of your combobox. But if this is straightforward display of what's selected, databindings is valid.

Good luck on your project!

Grtz.&copy;

D.

 

by: CodeCruiserPosted on 2009-09-04 at 07:09:30ID: 25259812

How about
Me.Label31.DataBindings.Add("Text", comboTest, "SelectedValue")

20120131-EE-VQP-002

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