Smart Transaction Manager
lazarus / 16-Databases

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DeBritto · 2016-06-06 00:38

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][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i public   
procedure OpenQuery(Q: TIBQuery; AForceRB: boolean = false);   
procedure ExecQuery(Q: TIBQuery; AForceRB: boolean = false;
FAutoCommit: boolean = false); //and in the implementation: procedure
TdMain.ExecQuery(Q: TIBQuery; AForceRB, FAutoCommit: boolean);begin 
if Q.Transaction.InTransaction then  // only rollback if active    if
AForceRB then      Q.Transaction.Rollback; if not
Q.Transaction.InTransaction then   
Q.Transaction.StartTransaction; try Q.ExecSQL; except  on E:Exception
do  begin    if Q.Transaction.InTransaction then     
Q.Transaction.RollBack;  Assert(false, 'An error has occurred while
executing the query '+Q.Name+'.'#13#13'Errormessage:
'+E.Message); end; if FAutoCommit then   
Q.Transaction.Commit;end; procedure TdMain.OpenQuery(Q: TIBQuery;
AForceRB: boolean);begin  if Q.Transaction.InTransaction then    if
AForceRB then      Q.Transaction.Rollback; if not
Q.Transaction.InTransaction then   
Q.Transaction.StartTransaction; try Q.Open; except  on E:Exception do 
begin Assert(false, 'An error has occurred while opening the query
'+Q.Name+'.'#13#13'Errormessage: '+E.Message); end; end;
In order to use these function think like this:
Some form, getting data to fill listbox:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
UpdateListbox;begin  qGet.SQL.Text:= 'SELECT NAME FROM CUSTOMERS ORDER
BY CITY'; dMain.OpenQuery(qGet, true); // force rollback before
opening - most recent data is wanted. while not qGet.Eof do  begin   
lbCustomers.Items.Add(qGet.Fields[0].AsString);    qGet.Next; 
end; qGet.Transaction.Commit;end;

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valdir.marcos · 2017-04-16 23:44

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

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valdir.marcos · 2017-04-16 23:48

Quote from: DeBritto on June 06, 2016, 02:38:07 amSmart 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.