Creating a Server Component with VB - Redesigned - Part 2

    ''''///// Check if any data was returned
    If Rs.EOF = True And Rs.BOF = True Then 

        ''''///// No data returned, set error information, raise error
        Err.Number = 40001
        Err.Source = "NoteProject::NoteClass::ShowNotes"
        Err.Description = "00000002<BR>Possible invalid lngNoteID entered as method value"
        Err.Raise Err.Number, Err.Source, Err.Description 

After assigning our error message values, we raise our error and send it off to the ErrorCode section at the very bottom of the method code, skipping all other method code. Of course, if a record is successfully returned, the Else section of our If/Then code will retrieve the record''''s NoteText field value and omit any of our error code.

    Else
        strNoteText = Rs.Fields("NoteText")
    End If

Down at the bottom of our method we have our error section that processes any errors that occur in our method, as well as the ones we raise ourselves. Since we originally opened a database transaction (and getting to this error code section assumes that we have skipped over the section of code that commits our database transaction), we need to let ADO know that we want any previous SQL statements undone. We do this with the objConn.RollbackTrans statement that rolls back any database work from the point in our code where we placed our objConn.BeginTrans statement.

    ''''///// ROLLBACK, CLOSE DB REFERENCES, AND SEND BACK RAISED ERROR
    objConn.RollbackTrans
    If IsObject(Rs) Then Set Rs = Nothing
    If IsObject(objCmd) Then Set objCmd = Nothing
    If IsObject(objConn) Then Set objConn = Nothing

Complete Code for Retrieving a Note''''s Text Here is the complete code for retrieving a note''''s text from the database. It''''s put together here so you can get a good overview of what has been discussed up to this point. We''''ll be adding more code to our method. At this point it might be advantageous to make sure you comprehend this code before going on to the next code section, which will demonstrate an alternative way to handle retrieved database values.

Here''''s what we covered so far:

Complete Code for Select Database Process

Public Function ShowNotes(ByVal lngNoteID As Long, _
	Optional ByVal intStyleID As Integer = 0, _
	Optional ByVal strURL As String = "NoteExample.asp", _
	Optional ByVal strDbConnectionString As String = "NotesDSN") As String

    ''''///// ERROR CODE //////////////////////////////////////////////
    On Error GoTo ErrorCode

    ''''///// DB Connectivity Variables
    Dim sql As String
    Dim Rs As New ADODB.Recordset
    Dim objCmd As New ADODB.Command
    Dim objConn As New ADODB.Connection

    ''''///// DB Value Storage variables
    Dim strNoteText As String

    ''''///// OPEN DATABASE ///////////////////////////////////////////
    objConn.Open strDbConnectionString
    objConn.BeginTrans

    ''''///// GET SELECTED NOTE TEXT FROM DATABASE ////////////////////
    sql = "SELECT NoteText FROM NoteTable WHERE NoteID = " & lngNoteID
    objCmd.CommandText = sql
    objCmd.CommandType = adCmdText
    Set objCmd.ActiveConnection = objConn
    Rs.Open objCmd

    ''''///// Check if any data was returned
    If Rs.EOF = True And Rs.BOF = True Then
        ''''///// No data returned, set error information, raise error
        Err.Number = 40001
        Err.Source = "NoteProject::NoteClass::ShowNotes"
        Err.Description = "00000002<BR>Possible invalid lngNoteID entered as method value"

        Err.Raise Err.Number, Err.Source, Err.Description
    Else
        strNoteText = Rs.Fields("NoteText")
    End If
    
    Rs.Close
    

    ''''--> ANY OTHER DATABASE CODE GOES HERE


    ''''///// FINISH AND CLOSE UP DATABASE PROCESSES //////////////////
    objConn.CommitTrans
    objConn.Close
    Set Rs = Nothing
    Set objCmd = Nothing
    Set objConn = Nothing


    ''''--> OTHER METHOD CODE GOES HERE


    ''''///// SEND BACK NOTE TEXT FROM DATABASE
    ShowNotes = strNoteText

    ''''///// EXIT FUNCTION IF NO ERROR RAISED ////////////////////////
    Exit Function
    
    ''''///// CODE IF ERROR OCCURS ////////////////////////////////////
ErrorCode:

    ''''///// ROLLBACK, CLOSE DB REFERRENCES, AND SEND BACK RAISED ERROR
    objConn.RollbackTrans
    If IsObject(Rs) Then Set Rs = Nothing
    If IsObject(objCmd) Then Set objCmd = Nothing
    If IsObject(objConn) Then Set objConn = Nothing
    Err.Raise Err.Number, Err.Source, Err.Description

End Function



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