Q229272: FIX: Datacombo Returns -2147217848 (80040e4e) Change Canceled

Article: Q229272
Product(s): Microsoft Visual Basic for Windows
Version(s): 2.0,2.1,2.5,6.0
Operating System(s): 
Keyword(s): kbCtrl kbVBp600 kbGrpDSVBDB kbGrpDSMDAC kbDSupport kbADO250 kbADO260 kbMDACNoSweep
Last Modified: 23-AUG-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
- ActiveX Data Objects (ADO), versions 2.0, 2.1, 2.5 
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SYMPTOMS
========

When using a DataCombo control, if the DataField property of the DataCombo is
bound to a numeric data type a problem may occur under the following
circumstances:

  The user clicks the combo box and moves the mouse over the entries in the
  drop-down portion of the combo box but does NOT choose an item from the list.
  The user then clicks another control so that the DataCombo loses focus and an
  attempt is made to update the underlying data source specified in the
  DataField property.

This action fails because the Text property of the combo is an empty string
(non-numeric) and the bound field is a numeric type. In this case the following
error message is returned:

  -2147217848 (80040e4e) The change was canceled during notification; no
  columns are changed.

RESOLUTION
==========

To work around this error check the Text property of the Datacombo. If it is
blank, cancel the update to the underlying records. This work around is
demonstrated in the code sample in the MORE INFORMATION section.

STATUS
======

This problem was fixed in Visual Basic 6.0 Service Pack 4 (SP4).

For additional information about Visual Studio service packs, click the article
numbers below to view the articles in the Microsoft Knowledge Base:

  Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

  Q194295 HOWTO: Tell That a Visual Studio Service Pack Is Installed

You can download the latest Visual Studio service pack from the following
Microsoft Web site:

  Visual Studio Product Updates
  (http://msdn.microsoft.com/vstudio/downloads/updates.asp)

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a new Visual Basic Standard EXE project.

2. Choose Components from the Project menu and then add a reference to Microsoft
  Datalist Controls 6.0 (OLEDB). Choose References from the Project menu and
  check Microsoft Active Data Objects.

3. Add a regular text box and a Datacombo to the default form.

4. Paste the following code into the default form:

  Private rsRowsource As ADODB.Recordset
  Private rsDataSource As ADODB.Recordset
  Private Sub DataCombo1_Validate(Cancel As Boolean)
      On Error Resume Next
      
  '    Uncomment this code as a workaround 
  '---------------------------------------
  '    If DataCombo1.Text = "" Then
  '        rsDataSource.Cancel
  '        rsDataSource.Move 0
  '        Exit Sub
  '
  '    End If

      rsDataSource.Move 0
      MsgBox Err.Number & vbCrLf & Err.Description

  End Sub
  Private Sub Form_Load()
      
      Set rsRowsource = New ADODB.Recordset
      rsRowsource.Fields.Append "ID", adInteger
      rsRowsource.Fields.Append "Descr", adVarWChar, 255
      rsRowsource.Open
      
      For x = 1 To 5
          rsRowsource.AddNew Array("ID", "Descr"), Array(x, "Descr" & Str(x))
      Next x
      
      Set rsDataSource = New ADODB.Recordset
      rsDataSource.Fields.Append "ID", adInteger
      rsDataSource.Fields.Append "Foreign_ID", adInteger
      rsDataSource.Open
          
      DataCombo1.ListField = rsRowsource(1).Name
      DataCombo1.DataField = rsDataSource(1).Name
      DataCombo1.BoundColumn = rsDataSource(0).Name
      Set DataCombo1.RowSource = rsRowsource
      Set DataCombo1.DataSource = rsDataSource

      rsDataSource.AddNew
      
  End Sub

5. Run the project. Click the DataCombo and move the mouse over the selections;
  however, do not select one.

6. Now click the other Textbox control so that the DataCombo loses focus. You
  will see the preceding error message display. Uncomment the commented lines
  of code to see the workaround.

REFERENCES
==========

For more information on the DataCombo control, please see the Visual Basic 6.0
On-line help.

Additional query words: datacombo dropdown

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Keywords          : kbCtrl kbVBp600 kbGrpDSVBDB kbGrpDSMDAC kbDSupport kbADO250 kbADO260 kbMDACNoSweep 
Technology        : kbVBSearch kbAudDeveloper kbADOsearch kbADO210 kbADO200 kbADO250 kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVB600
Version           : :2.0,2.1,2.5,6.0
Issue type        : kbbug
Solution Type     : kbfix

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