In this process, there are 2 approaches, quite different
.
What I think is very frustrating is to fill up a form (can be long),
and find out that your time is lost because someone was quicker than
you to post.
The other approach is to implement a "lock" mechanisms (I know it can
be quite complex, mainly if the user shut down the computer etc ..but
can be handled), to avoid other people being able to get a record for
modifying when someone else can possibly modify it before you do ...
A part from this, I did not try your solution, but seems to handle the
case, maybe a bit costive thought. Using the security component can
avoid people to post after a certain time .. a way to explore ...
hth
On Jun 24, 4:06 pm, Marc MENDEZ <[EMAIL PROTECTED]> wrote:
> Hi,
>
> I asked a few days ago how to handled concurrency with Cake. Thanks to
> some members of this group, examples and time, I have a possible solution.
> However, I need your experience to validate this solution.
>
> I want to warn users when a record they save was modified in the
> meanwhile by somebody else.
> I add a datetime column in the table called "tst" (I can't use
> "modified" column, 'cause the value of this column seems to be updated
> before the callback 'beforeSave'... and of course, I use beforeSave
> method !).
> On the beforeSave(), I start a transaction and lock "for update" the
> record. Then I compare the tst value with the value I retrieved. If it's
> the same, I go on and update the tst value with the current datetime. If
> not, I halt the process with an error.
> I must add in my view $form->hidden("model.tst").
> I should do the same kind of process on beforeDelete()
> If a deadlock or timeout occurs, I handle these errors somewhere else.
>
> Any opinion ? A way to improve it ?
>
> Thanks !
>
> function beforeSave()
> {
> foreach ($this->data as $key=>$value)
> {
> if (!isset($value['tst']))
> {
> continue;
> }
> $pkValue = $this->id;
> $pkCol = $this->primaryKey;
> $pkType = $this->getColumnType($this->primaryKey);
> $db =& ConnectionManager::getDataSource($this->useDbConfig);
> $db->begin($this);
> $sql = "SELECT tst FROM " . $this->table . " WHERE " .
> $pkCol . " = ";
> switch ($pkType) {
> case 'integer': // TODO : add other numeric type
> break;
> default:
> $pkValue = "'".$pkValue."'";
> break;
> }
>
> $sql.=$pkValue. " FOR UPDATE";
> $modifiedInDB = $this->query($sql);
> if (!count($modifiedInDB))
> {
> // Record deleted
> $this->WWsetSqlErrMsg("Enregistrement déjà supprimé");
> $db->rollback($this);
> return false;
> }
> if ($modifiedInDB[0][$this->table]['tst'] != $value['tst'])
> {
> // Record deleted by somebody else
> $this->WWsetSqlErrMsg("Enregistrement modifié par un
> autre utilisateur");
> $db->rollback($this);
> return false;
> }
> else
> {
> $this->set('tst',date("Y-m-d G:i:s",strtotime('now')));
> }
> }
> return true;
> }
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