PRB: Clone Won't Support All ListFields & ListIndexes Methods

• Standard, Professional, and Enterprise Editions of Microsoft Visual Basic,16-bit and 32-bit, for Windows, version 4.0

SYMPTOMS

The ListFields (Dynaset and Snapshot method) and ListIndexes (Table method) used against a Clone created from a RecordSet object will generate the following error with the Microsoft DAO 3.0 Object Library:

   Function marked as restricted or uses an OLE type not supported in
   Visual Basic

   Run-time error '3251'
   Feature not available

CAUSE

When a Clone is created from any type of RecordSet object, the resulting Clone is a RecordSet object -- not the Visual Basic version 3.0 DynaSet, SnapShot, or Table types. It is not dependent on the type of the object from which it was created. Because the Clone is a RecordSet, only RecordSet properties and methods are available.

RESOLUTION

Visual Basic Version 4.0

The ListFields and ListIndexes methods are included in Visual Basic version 4.0 for compatibility with earlier versions of Visual Basic. For all RecordSet objects, Microsoft recommends that you enumerate the Fields or Indexes collection of the object containing the fields or indexes you want to list.

For Cloned objects, you may need to recode any use of the ListIndexes to enumerate the Fields or Indexes collection of the object. For more information, please see the "Examples of Converting Code to Jet Version 2.5" topic in the Visual Basic version 4.0 Help menu.

Steps to Demonstrate the Correct Alternative to ListFields

1. Start a new project in Visual Basic. Form1 is created by default.

2. Add a data control (Data1) to Form1.

3. Set the following properties for Data1.

      Property       Value
      -------------------------
      Databasename   Biblio.MDB
      RecordSource   Authors
   
   

4. Add the following code to the Form1_Click procedure:

      Sub Form1_Click ()
         Dim RS As RecordSet
         Set RS = Data1.Recordset.Clone()
         For Each Fld In RS.Fields
            Print Fld.Name
         Next
      End Sub
   
   

5. Start the program by choosing Start from the Run menu or by pressing the F5 key.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior in Visual Basic

1. Start a new project in Visual Basic. Form1 is created by default.

2. Add a data control (Data1) to Form1.

3. Set the following properties for Data1:

      Property       Value
      -------------------------
      Databasename   Biblio.MDB
      RecordSource   Authors
   
   

4. Add the following code to the Form1_Click procedure:

      Sub Form1_Click ()
         Dim DS As Dynaset, LF As Snapshot
         Set DS = Data1.Recordset.Clone()
         Set LF = DS.Listfields()
         While Not LF.EOF()
            Print LF("name")
            LF.Movenext
         Wend
      End Sub
   
   

5. Start the program by choosing Start from the Run menu or by pressing the F5 key.