BUG: Private UserControls Do Not Support Data Binding

• Microsoft Visual Basic Control Creation, Professional, and Enterprise Editions for Windows, version 5.0

SYMPTOMS

A UserControl created within a Standard EXE as a private object will not correctly bind its defined bound properties after the application is compiled to an EXE. While the application is debugged in the Visual Basic 5.0 IDE, the control and its binding function correctly.

CAUSE

RESOLUTION

The only workaround is to compile a separate binary for the OCX to be a public control. In this fashion, the bindable public properties function correctly.

To hide the use of this control adequately from other applications (one of the main benefits of a private UserControl) the author should add run-time licensing support to minimize the use of the control outside the intended application.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Steps to Reproduce

1. Create a new Standard EXE project.

2. Add a private UserControl (UserControl1) to the project.

3. Add a label (Label1) to the UserControl.

4. Add the following code to the UserControl:

         Public Property Get Value() As Variant
             Value = Label1.Caption
         End Property
   
         Public Property Let Value(ByVal vNewValue As Variant)
             Label1.Caption = vNewValue
         End Property
   
   

5. From the Tools Menu, select Procedure Attributes.

6. In the Procedure Attributes dialog Window, click the Advanced button.

7. In the Data Binding section, check "Property is databound" and "This property binds to DataField." Click OK.

8. Close the UserControl designer and code window.

9. Add a Data control to Form1.

10. Set the following properties of the Data control:

          DatabaseName ="C:\Program Files\Microsoft Visual Basic\Biblio.mdb"
          DefaultCursorType = 0
          DefaultType = 2
          ReadOnly = False
          RecordsetType = 1
          RecordSource = "Authors"
    

11. Add an instance of UserControl1 to the form.

12. Change the following properties of UserControl11.

          DataField= "Author"
          DataSource= "Data1"
    

13. Run the application by pressing the F5 key.

14. Move through the authors in Biblio using the Data control (just to

        verify that everything works in the IDE).
    

15. Compile to EXE.

16. Run the EXE. Note that the "bound" property of the UserControl does not

        change as it did in the IDE.
    

REFERENCES

For more information about licensing processes, see the Microsoft Visual Basic Books Online:

Component Tools Guide

   Creating ActiveX Components
      Building ActiveX Controls
         Distributing Controls

Keywords          : vb5all
Version           : 5.0
Platform          : WINDOWS
Issue type        : kbbug