HOWTO: Use UDT to Return State Info for Out-of-Process Record

• ActiveX Data Objects (ADO), versions 2.0, 2.01, 2.1, 2.1 SP1, 2.1 SP2
• Microsoft Visual Basic Professional and Enterprise Editions for Windows, versions 5.0, 6.0

SUMMARY

Not all state information is marshalled for an out-of-process ADO Recordset. This is done for performance reasons. For details, please refer to the following article in the Microsoft Knowledge Base:

Q185423 PRB: Most ADO Recordset Properties Are Not Marshalled

MORE INFORMATION

The following code demonstrates using a UDT to pass an ADO.Recordset out of process with non-marshaled state information. Note: This sample is dependent on the SQL Server 'Pubs' database and 'Employee' table.

1. Create an ActiveX EXE project (this is the Server). Under the Project menu, choose References and add a reference to the Microsoft ActiveX Data Object Library. Paste the following code in the General Declarations section:




Option Explicit
Private strSQL As String
Private strConnect As String
Private ADOCn As ADODB.Connection

Type adoUDTRs
    strSource As String
    intState As Integer
    udtRs As ADODB.Recordset
End Type

Public Function GetRs() As adoUDTRs
If Not ADOCn Is Nothing Then
Else
    Err.Raise vbObjectError + 98, "GetRs", "No valid Connection"
End If
Dim adoRs As ADODB.Recordset
Dim objUDTRs As adoUDTRs
Set adoRs = New ADODB.Recordset
With adoRs
    .CursorLocation = adUseClient
    .ActiveConnection = ADOCn
    .CursorType = adOpenStatic
    .LockType = adLockBatchOptimistic
    .Open strSQL
End With
'disConnect the Recordset.
Set adoRs.ActiveConnection = Nothing
With objUDTRs
    .strSource = adoRs.Source
    .intState = adoRs.State
    Set .udtRs = adoRs
End With
GetRs = objUDTRs
Set adoRs = Nothing
End Function

Private Property Get ConnectStr() As String
ConnectStr = strConnect
End Property

Private Property Let ConnectStr(strCn As String)
strConnect = strCn
End Property

Public Property Get SQL() As String
SQL = strSQL
End Property

Public Property Let SQL(nSQL As String)
strSQL = nSQL
End Property

Public Sub UpdateRs(ByVal ClientRs As ADODB.Recordset)
    Dim adoRs As New ADODB.Recordset
    If Not ADOCn Is Nothing Then
    Else
        Err.Raise vbObjectError + 99, "UpdateRs", "No valid Connection"
    End If
    adoRs.ActiveConnection = strConnect
    adoRs.Open ClientRs
    adoRs.UpdateBatch
End Sub

Public Sub ADOConnect(strConnect As String, Optional CmdTimeOut As Integer = 20)
Set ADOCn = New ADODB.Connection
With ADOCn
    .ConnectionString = strConnect
    .CursorLocation = adUseClient
    .CommandTimeout = CmdTimeOut
    .Open
End With
ConnectStr = ADOCn
End Sub 

2. Change the name of the project to 'adoProc' and the name of the class to 'adoProcRs.'



3. Run the ActiveX EXE project (Server).



4. Create a Standard EXE project (this is the Client). Under the Project menu, choose References and add a reference to the adoProc component. Paste the following code in the General Declarations section:




Const strConnect = "Driver={SQL Server};Server=<myServer>;Database=Pubs;Uid=<myUserID>;Pwd=<myPassword>"

Private Sub Command1_Click()
On Error GoTo ErrorHandler
    Dim objAdoRs As adoUDTRs
    Dim objAdoData As New adoProcRs
    Dim strInsertID As String
    strInsertID = Text1.Text
    With objAdoData
        .SQL = "SELECT * FROM Employee WHERE Emp_ID = '" & strInsertID & "'"
        .ADOConnect strConnect, 20 'Establish connection.
    End With
    'Return the Resultset from Data Object.
    objAdoRs = objAdoData.GetRs
    'values of state info in UDT.
    Debug.Print objAdoRs.intState
    Debug.Print objAdoRs.strSource
    'state info in Recordset.
    Debug.Print objAdoRs.udtRs.State    'this persists out of proc.
    Debug.Print objAdoRs.udtRs.Source  'this does not.
    'modify a value and send back object for update.
    objAdoRs.udtRs(1).Value = "YYYZZZ"
    objAdoData.UpdateRs objAdoRs.udtRs
    MsgBox "Data Changed", vbOKOnly, "Data Object"
    Exit Sub
    
ErrorHandler:
    MsgBox "Change Failed:" & vbCrLf & Err.Number & vbCrLf & Err.Description, vbOKOnly, "Data Object"
    Exit Sub
End Sub 

5. Change the Connect string information as needed for your SQL Server.



6. Add a TextBox to the Form and set the Text property = TPO55093M.



7. Add a Command button to the Form.



8. Run the Standard EXE project (Client) and click the Command button. Note the output in the Immediate window that indicates which state information was returned from the UDT and the ADO.Recordset.
   
   This sample also works for an MTS package but you will want to modify it to use CreateObject instead of the New keyword. Also, if you need to use late binding for this sample, for instance ASP, then simply change the Client code as follows:




    'Dim objAdoRs As adoUDTRs
    Dim objAdoRs As Variant
    'Dim objAdoData As New adoProcRs
    Dim objAdoData As Object
    Dim strInsertID As String

    strInsertID = Text1.Text
    
    Set objAdoData = CreateObject("adoProc.adoProcRs")
    With objAdoData
        .SQL = "SELECT * FROM Employee WHERE Emp_ID = '" & strInsertID & "'"
        .ADOConnect strConnect, 20 'Establish connection.
    End With 

REFERENCES

For more information, please see the following article in the Microsoft Knowledge Base:

Q185423 PRB: Most ADO Recordset Properties Are Not Marshalled

Additional query words:

Keywords          : kbADO kbDatabase kbMTS kbSQLServ kbVBp kbGrpVBDB 
Version           : WINDOWS:2.0,2.01,2.1,2.1 SP1,2.1 SP2,5.0,6.0
Platform          : WINDOWS 
Issue type        : kbhowto 

Last Reviewed: June 9, 1999