c++ - QT SQL notification with payload -

i'm working on applciation add table view new row, inserted db's table. started basic class handle notifies , setted triggers:

create or replace function notify_tableiwanttoobserve_update()   returns trigger $$ declare begin     perform pg_notify(         cast('tableiwanttoobserve_update' text),         (new.tableiwanttoobserve_id)::text);     return new; end; $$ language plpgsql;  create trigger trigger_notify_tableiwanttoobserve_update   after update   on tableiwanttoobserve   each row   execute procedure notify_tableiwanttoobserve_update(); 

so jsut send notfy id of updated row in payload. want - becous reloading whole table won't trick later.

i checked documentaton of qsqldriver http://doc.qt.io/qt-5/qsqldriver.html#notification-1

with it, created "handler":

// that's constructor

        mydb =  new qsqldatabase(qsqldatabase::adddatabase("qpsql", "main"));          //removed data here (just fro sake of post)         mydb->sethostname("-");         mydb->setport(0);         mydb->setdatabasename("-");         mydb->setusername("-");         mydb->setpassword("-");          mydb->open();       if( mydb->isopen() )         {         qdebug()<<"connected db!";         qobject::connect(                 mydb->driver(),                 signal(notification(const qstring&, qsqldriver::notificationsource, const qvariant)),                 this,                                    slot(slot_dbnotification_recieved_notifiandpayload((const qstring&, const qvariant)));                 );         }         else         qdebug()<<"not connected db!"; 

but jsut wont work. driver's signal useing single qstring connect - version needed (with additional info) wont connect.

i updated qt 5.7, still in qtcreater, shows me driver's signal single string.

is there fix that? realy need use signal retrieve updated row id.

edit 1:

that slot of handler:

        void notifihandlerr::slot_dbnotification_recieved_notifiandpayload(const qstring& msg, const qvariant &payload)         {             qdebug() << "i notified : " + msg+" data : "+payload.tostring();         } 

edit 2:

i tried add qsqldriver::notificationsource argument in slot, couldn't - still repeated error in .h notificationsource wasn't declared.

edit 3:

i'm adding here of code (handler class)

        // whole .h         #include <qdebug>         #include <qobject>         #include <qstring>         #include <qsqldatabase>         #include <qsqldriver>         #include <qvariant>         #include <qsqldriverplugin>         #include <qsqldriver.h>           class handler : public qobject         {             q_object         public slots:             void slot_dbnotification_recieved_notifiandpayload                 (const qstring& name, qsqldriver::notificationsource source, const qvariant& payload);          public:             explicit handler();             ~handler();          private:             qsqldatabase mydb;         };               //whole .cpp         #include "handler.h"          handler::handler()         {         mydb =  new qsqldatabase(qsqldatabase::adddatabase("qpsql", "main"));              mydb->sethostname("-");             mydb->setport(0);             mydb->setdatabasename("-");             mydb->setusername("-");             mydb->setpassword("-");              mydb->open();               if( mydb->isopen() )             {             qdebug()<<"connected db!";             mydb->driver()->subscribetonotification("tableiwanttoobserve_update");             qobject::connect(                 mydb->driver(),                 signal(notification(const qstring&, qsqldriver::notificationsource, const qvariant)),                 this,                                    slot(slot_dbnotification_recieved_notifiandpayload((const qstring&, const qvariant)));                 );             }             else             qdebug()<<"not connected db!";         }          handler::~handler()         {                mydb->driver()->unsubscribefromnotification("tableiwanttoobserve_update");     mydb->cloe();         }          void notificationmaster::slot_dbnotification_recieved_notifiandpayload         (const qstring &name, qsqldriver::notificationsource source, const qvariant &payload)         {             qdebug() << "i notified : " + name+" data : "+payload.tostring();         } 

and eliminate idea - added

            qt += sql 

in .pro file

your slot has wrong signature, here how should define it.

in header file:

//in order able use enum qsqldriver::notificationsource #include <qsqldriver> ... ...  class handler : public qobject{     q_object public:     explicit handler(qobject *parent = 0);     ~handler();     ...     ...     ... public slots:     void sqlnotification(const qstring& name, qsqldriver::notificationsource source,                          const qvariant& payload);     ...     ... }; 

and in constructor, when connecting slot, should subscribe notification first:

qsqldatabase::database().driver()->subscribetonotification("notification_name"); connect(qsqldatabase::database().driver(),         signal(notification(qstring,qsqldriver::notificationsource,qvariant)), this,         slot(sqlnotification(qstring,qsqldriver::notificationsource,qvariant))); 

you may need unsubscribe in destructor(since don't want receive notification more):

qsqldatabase::database().driver()->unsubscribefromnotification("notification_name"); 

and slot implementation:

void handler::sqlnotification(const qstring &name, qsqldriver::notificationsource source, const qvariant &payload){     switch(source){     case qsqldriver::unknownsource:         qdebug() << "unkown source, name: " << name << "payload:" << payload.tostring();         break;     case qsqldriver::selfsource:         qdebug() << "self source, name: " << name << "payload:" << payload.tostring();         break;     case qsqldriver::othersource:         qdebug() << "other source, name: " << name << "payload:" << payload.tostring();         break;     } }