QSqlDriver notification

Yacinoben

Hello,
I would like to use a notifications of QSqlDriver when a value in the table (Count) has changed.

I use Postgre.

code source :

   if(!query.exec("Notify Count"))
                   qDebug()<<query->lastError().text();

   if(!m_db.driver()->subscribeToNotification("Count"))
     {
       qDebug()<<m_db.driver()->lastError().text();
       m_db.close();
       qApp->quit();
     }
  connect(m_db.driver(), static_cast<void(QSqlDriver::*)(const QString &)>(&QSqlDriver::notification), [](const QString &name){qDebug("notification"); });

When the table is updated by another program, i don't receive a notification.

source code of the other program :

 if(!query.exec("UPDATE Count SET  Counter = Counter+1"))
             qDebug()<<)query.lastError().text();

Thank's

mrjj

Hi
But you do get a notification if same program changes the db ?

Yacinoben

No, i haven't a notification

mrjj

@Yacinoben

Did you check with HasFeature if it can do it ?
http://doc.qt.io/qt-5/qsqldriver.html#hasFeature

Yacinoben

  qDebug()<<m_db.driver()->hasFeature(QSqlDriver::EventNotifications);

return true.

mrjj

Super. it should work.
I dont have PostG. DB so can't play with it

Does the queries all work ?

Syntax looks odd to me but I guess its valid

https://www.postgresql.org/docs/9.0/static/sql-notify.html

Sorry, not sure how to test this further.

Yacinoben

All query works, I don't know what to do

mrjj

@Yacinoben
Hi
I would find some other tool to test if notification does indeed work.
So i know it must be something in my program or Qt.

https://jdbc.postgresql.org/documentation/91/listennotify.html

Yacinoben

up ?
I have tried everything, but nothing.

Yacinoben

it's solved. In postgre i wrote "CREATE RULE name AS ON UPDATE TO nameTable DO NOTIFY notification_name

https://www.postgresql.org/docs/8.1/static/rules-update.html