Smart Transaction Manager

[DeBritto]

Hi everyone,
I'm starting to deal with transactions in my app and I've found this code at this web site (From: http://delphi.xcjc.net//viewthread.php?tid=48818).

But unfortunately I still doesn't know how to change it to work in Free Pascal/Lazarus using the basic components. I'm using Firebird 2.5 as database. I thought that this code could be usefull not only for me. Could anyone help me translate it to work in Free Pascal/Lazarus?

Other question, do you think that this logic works well?


{Smart Transaction Management with Firebird/Interbase}

Add the following functions to your main datamodule (dmMain)

Code: Pascal  [Select][+][-]

1. public
2.     procedure OpenQuery(Q: TIBQuery; AForceRB: boolean = false);
3.     procedure ExecQuery(Q: TIBQuery; AForceRB: boolean = false; FAutoCommit: boolean = false);
4.  
5. //and in the implementation:
6.  
7. procedure TdMain.ExecQuery(Q: TIBQuery; AForceRB, FAutoCommit: boolean);
8. begin
9.   if Q.Transaction.InTransaction then  // only rollback if active
10.     if AForceRB then
11.       Q.Transaction.Rollback;
12.  
13. if not Q.Transaction.InTransaction then
14.     Q.Transaction.StartTransaction;
15.  
16. try
17.  
18. Q.ExecSQL;
19.  
20. except
21.   on E:Exception do
22.   begin
23.     if Q.Transaction.InTransaction then
24.       Q.Transaction.RollBack;
25.  
26. Assert(false, 'An error has occurred while executing the query '+Q.Name+'.'#13#13'Errormessage: '+E.Message);
27.  
28. end;
29.  
30. if FAutoCommit then
31.     Q.Transaction.Commit;
32. end;
33.  
34. procedure TdMain.OpenQuery(Q: TIBQuery; AForceRB: boolean);
35. begin
36.   if Q.Transaction.InTransaction then
37.     if AForceRB then
38.       Q.Transaction.Rollback;
39.  
40. if not Q.Transaction.InTransaction then
41.     Q.Transaction.StartTransaction;
42.  
43. try
44.  
45. Q.Open;
46.  
47. except
48.   on E:Exception do
49.   begin
50.  
51. Assert(false, 'An error has occurred while opening the query '+Q.Name+'.'#13#13'Errormessage: '+E.Message);
52.  
53. end;
54.  
55. end;

In order to use these function think like this:
Some form, getting data to fill listbox:

Code: Pascal  [Select][+][-]

1. procedure UpdateListbox;
2. begin
3.   qGet.SQL.Text:= 'SELECT NAME FROM CUSTOMERS ORDER BY CITY';
4.  
5. dMain.OpenQuery(qGet, true); // force rollback before opening - most recent data is wanted.
6.  
7. while not qGet.Eof do
8.   begin
9.     lbCustomers.Items.Add(qGet.Fields[0].AsString);
10.     qGet.Next;
11.   end;
12.  
13. qGet.Transaction.Commit;
14. end;

[valdir.marcos]

More than 10 months have passed, just as a curiosity, have you found a solution for you?

[valdir.marcos]

Smart Transaction Management with Firebird/Interbase
http://delphi.xcjc.net//viewthread.php?tid=48818).

... do you think that this logic works well?

No.
If you are working with transactions on RAD, you'd better be explicit using try/except and commit/rollback whenever they are necessary.
That's make you code clear for you and for future maintain.