Domino developers typically try to retrieve Lotus Notes documents by using the GetDocumentByUnid method in LotusScript like this:
set doc = db.Getdocumentbyunid(unid$)
if doc is nothing then
' Do something
else
' Do something
end if
This is actually an incorrect way of implementing the GetDocumentByUnid in LotusScript. When the GetDocumentByUnid method doesn't find a Lotus Notes document, it gives an error message. Also, if used improperly, it may return an irrelevant "ghost" Lotus Notes document, also known as a deletion stub.
Use this LotusScript function instead to correctly and safely return a relevant Lotus Notes document (or nothing, if there isn't one):
set doc = DatabaseGetDocumentByUnid
(db, unid$) if doc is nothing then
' Do something
else
' Do something
end if
Here is the LotusScript function:
Function DatabaseGetDocumentByUnid
(db As NotesDatabase, unid$)
As NotesDocument
On Error 4091 Resume Next
Set DatabaseGetDocumentByUnid =
Nothing
Set DatabaseGetDocumentByUnid =
db.GetDocumentByUnid(unid$)
If Err = 4091 And
( DatabaseGetDocumentByUnid Is Nothing )
Then
Err = 0
Set DatabaseGetDocumentByUnid = Nothing
Exit Function
End If
If DatabaseGetDocumentByUnid Is Nothing Then
Set DatabaseGetDocumentByUnid = Nothing
Exit Function
End If
If DatabaseGetDocumentByUnid.Size = 0
Or DatabaseGetDocumentByUnid.UniversalID =
"" Or DatabaseGetDocumentByUnid.IsDeleted
Then
Set DatabaseGetDocumentByUnid = Nothing
Exit Function
End If
End Function
MEMBER FEEDBACK TO THIS TIP
I would add one additional check to the bottom of this method, which I think is an excellent example of code reuse and data abstraction in LotusScript.
I would modify the following block of code:
If DatabaseGetDocumentByUnid.Size = 0
Or DatabaseGetDocumentByUnid.UniversalID =
"" Or DatabaseGetDocumentByUnid.IsDeleted
Then
Set DatabaseGetDocumentByUnid = Nothing
Exit Function
End If
I would include an additional check for .IsValid. The .IsValid command will tell you if the document is initially in existence (not a deletion stub). Because deletion stubs are visible from the indexer, any Lotus Notes documents that are deleted before the indexer runs will not be valid -- but they won't appear as deleted either. You must check for .IsValid as well. Try the following:
If DatabaseGetDocumentByUnid.Size = 0 Or _
DatabaseGetDocumentByUnid.UniversalID = "" Or _
DatabaseGetDocumentByUnid.IsDeleted Or _
(Not DatabaseGetDocumentByUnid.IsValid) Then
Set DatabaseGetDocumentByUnid = Nothing
Exit Function
End If
—Todd F.
******************************************
To accomplish this, I simply use GetDocumentByUnid and code similar to:
If not (doc is nothing) then
If doc.IsValid And Not doc.IsDeleted Then…
—Larry D.
******************************************
This is how this function should have been written:
Function DatabaseGetDocumentByUnid
(db As NotesDatabase, unid$) As NotesDocument
On Error Goto ErrorHandler
Set DatabaseGetDocumentByUnid = Nothing
Set DatabaseGetDocumentByUnid =
db.GetDocumentByUnid(unid$)
If DatabaseGetDocumentByUnid Is Nothing Then
Set DatabaseGetDocumentByUnid = Nothing
Else
If DatabaseGetDocumentByUnid.Size = 0 Or _
DatabaseGetDocumentByUnid.UniversalID = "" Or _
DatabaseGetDocumentByUnid.IsDeleted Then
Set DatabaseGetDocumentByUnid = Nothing
End If
End If
Exit Function
ErrorHandler:
If Err = 4091 Then
If DatabaseGetDocumentByUnid Is Nothing Then
Set DatabaseGetDocumentByUnid = Nothing
End If
Resume Next
Else
Resume ExitWithError
End If
ExitWithError:
End Function
—David D.
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