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  4. tableView->setModel(model); causes SIGSEGV.
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tableView->setModel(model); causes SIGSEGV.

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  • Christian EhrlicherC Christian Ehrlicher

    @snubben said in tableView->setModel(model); causes SIGSEGV.:

    model 0x0

    As you can see your model pointer is a nullptr, same goes for tableview and 'this' pointer.

    snubbenS Offline
    snubbenS Offline
    snubben
    wrote on last edited by
    #3

    @Christian-Ehrlicher said in tableView->setModel(model); causes SIGSEGV.:

    @snubben said in tableView->setModel(model); causes SIGSEGV.:

    model 0x0

    As you can see your model pointer is a nullptr, same goes for tableview and 'this' pointer.

    OK, so if I comment out

    tableView->setModel(model);
    

    the application runs fine (except it is not showing data). I would expect it to crash and burn since I am using the model pointer for other things but it is not(?). But there is much I don't know about Qt/C++.
    I have seen that under "Locals" before, sometimes it shows what looks like a valid address, sometimes not. I wonder if I am doing something wrong debugging. I used "Jump to line" to get to the position of "setmodel()". Debugging is so different from VS.

    I can post only every 600 secs, can you upvote my initial post? I'll be gray and in a wheelchair otherwise before this thread is solved.

    1 Reply Last reply
    0
    • snubbenS Offline
      snubbenS Offline
      snubben
      wrote on last edited by
      #4

      OK, I hit the F5 now while debugging to get to the location where it crashes. Now it shows valid values.

      	Locals		
      		model	@0x5555557a9750	QSqlQueryModel
      		prodCount	0	int
      		query	@0x7fffffffdaa0	QSqlQuery
      		queryString	"SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;"	QString
      		queryTimeout	0	int
      		dateMin	Sat Jan 1 2000	QDate
      		field3	""	QString
      		tableView	@0x5555557dfbe0	QTableView
      		this	@0x555555714c70	DatabaseHandler
      		useDateSearch	false	bool
      		field1	""	QString
      		field2	""	QString
      	Inspector		
      	Expressions		
      	Return Value		
      	Tooltip		
      
      JonBJ 1 Reply Last reply
      0
      • snubbenS snubben

        OK, I hit the F5 now while debugging to get to the location where it crashes. Now it shows valid values.

        	Locals		
        		model	@0x5555557a9750	QSqlQueryModel
        		prodCount	0	int
        		query	@0x7fffffffdaa0	QSqlQuery
        		queryString	"SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;"	QString
        		queryTimeout	0	int
        		dateMin	Sat Jan 1 2000	QDate
        		field3	""	QString
        		tableView	@0x5555557dfbe0	QTableView
        		this	@0x555555714c70	DatabaseHandler
        		useDateSearch	false	bool
        		field1	""	QString
        		field2	""	QString
        	Inspector		
        	Expressions		
        	Return Value		
        	Tooltip		
        
        JonBJ Offline
        JonBJ Offline
        JonB
        wrote on last edited by
        #5

        @snubben
        You need to show the stack trace pane when it crashes (not the variables pane).

        snubbenS 1 Reply Last reply
        0
        • snubbenS snubben

          Hi,
          I am new to C++ and Qt. This is the 2nd day I have been trying to fix this and I can't get further (GPT4 is out of answers too).
          I am on Manjaro, Qt 6.7.2. Using MariaDB.
          I can see from the MariaDB log that the SQL is executed just fine by the query.

          But when I do "tableView->setModel(model);" it seg faults. I don't know where to look for more information with Qt Creator or C++. I have also tried a variant that uses bindValue(":field1", field1) but I guess the problem is elsewhere.
          EDIT:
          It is not here that it crashes >> tableView->setModel(model);
          It seems it is in qsql_mysql.cpp:459.

          bool QMYSQLResult::fetch(int i){
          ...
             int nRC = mysql_stmt_fetch(d->stmt);
          ...
          

          In the below example there are no search criterias added so it doesn't bind anything.

          void DatabaseHandler::getProducts(QTableView* tableView,
                                         const QString field1,
                                         const QString field2,
                                         const bool useDateSearch,
                                         const QDate dateMin,
                                         const QString field3,
                                         int prodCount,
                                         int queryTimeout) {
              if (!db.isOpen()) {
                  qCritical() << "Database is not open.";
                  //emit errorOccurred(db.lastError().text());
                  return;
              }
          
              QString queryString = QString(
                  "SELECT "
                  "field1 , "
                  "field2, "
                  "prodCount , "
                  "field3 , "
                  "prod_date "
                  "FROM products "
                  "WHERE 1 = 1");
          
              if (!field1.isEmpty()) {
                  queryString += field1.contains('%') ? " AND field1 LIKE ?" : " AND field1 = ?";
              }
              if (!field2.isEmpty()) {
                  queryString += field2.contains('%') ? " AND field2 LIKE ?" : " AND field2 = ?";
              }
              if (useDateSearch && dateMin.isValid()) {
                  queryString += " AND prod_date >= ?";
              }
              if (!field3.isEmpty()) {
                  queryString += " AND field3 = ?";
              }
              if (prodCount > 0) {
                  queryString += " AND prodCount >= ?";
              }
          
              queryString += " ORDER BY prod_date DESC;";
          
              QSqlQuery query(db);
          
              query.prepare(queryString);
              if(HasError(query)) return;
          
              if (!field1.isEmpty()) {
                  query.addBindValue(field1);
                  if(HasError(query)) return;
              }
              if (!field2.isEmpty()) {
                  query.addBindValue(field2);
                  if(HasError(query)) return;
              }
              if (useDateSearch && dateMin.isValid()) {
                  query.addBindValue(dateMin);
                  if(HasError(query)) return;
              }
              if (!field3.isEmpty()) {
                  query.addBindValue(field3);
                  if(HasError(query)) return;
              }
              if (prodCount > 0) {
                  query.addBindValue(prodCount);
                  if(HasError(query)) return;
              }
          
              query.exec();
              if(HasError(query)) return;
          
              QSqlQueryModel* model = new QSqlQueryModel(this);
              if(HasError(model)) return;
          
              model->setQuery(std::move(query));
              if(HasError(model)) return;
          
              model->setHeaderData(0, Qt::Horizontal, "Field 1", Qt::ImReadOnly);
              model->setHeaderData(1, Qt::Horizontal, "Field 2", Qt::ImReadOnly);
              model->setHeaderData(2, Qt::Horizontal, "Field 3", Qt::ImReadOnly);
              model->setHeaderData(3, Qt::Horizontal, "Field 4", Qt::ImReadOnly);
              model->setHeaderData(4, Qt::Horizontal, "Field 5", Qt::ImReadOnly);
          
              qDebug() << "HERE";
              tableView->setModel(model);
              qDebug() << "HERE2";
              tableView->show();
          }
          
          
          	Locals		
          		model	0x0	QSqlQueryModel*
          		prodCount	-1	int
          		query	@0x5555558149e0	QSqlQuery
          		queryString	<not accessible>	QString
          		queryTimeout	1433365632	int
          		dateMin	Sat Feb 28 -4713	QDate
          		field3	<not accessible>	QString
          		tableView	0x0	QTableView*
          		this	0x0	DatabaseHandler*
          		useDateSearch	false	bool
          		field1	<not accessible>	QString
          		field2	<not accessible>	QString
          	Inspector		
          	Expressions		
          	Return Value		
          	Tooltip		
          		Qt	<no such value>	 
          
          Pl45m4P Offline
          Pl45m4P Offline
          Pl45m4
          wrote on last edited by
          #6

          Hi, the crucial parts are here

          @snubben said in tableView->setModel(model); causes SIGSEGV.:

          void DatabaseHandler::getProducts(QTableView* tableView,
          

          and then here, where it seem to crash

          tableView->setModel(model);
          

          How do you pass the view to this function? How and where do you create it?

          Also:

          if (!db.isOpen()) {
          

          This looks like you store your db connection as private member in DatabaseHandler.
          Don't do that, it might cause undefined behavior. Better use the static QSqlDatabase::database() whenever it's needed.


          If debugging is the process of removing software bugs, then programming must be the process of putting them in.

          ~E. W. Dijkstra

          snubbenS 1 Reply Last reply
          0
          • JonBJ JonB

            @snubben
            You need to show the stack trace pane when it crashes (not the variables pane).

            snubbenS Offline
            snubbenS Offline
            snubben
            wrote on last edited by
            #7

            @JonB said in tableView->setModel(model); causes SIGSEGV.:

            @snubben
            You need to show the stack trace pane when it crashes (not the variables pane).

            1  mysql_stmt_fetch                                                                       0x7ffff0cf91e4 
            2  QMYSQLResult::fetch                                    qsql_mysql.cpp             459  0x7ffff2a2b7da 
            3  QSqlQuery::seek                                        qsqlquery.cpp              616  0x7ffff7f90b5d 
            4  QSqlQueryModel::data                                   qabstractitemmodel.h       129  0x7ffff7f9b12b 
            5  QAbstractItemModel::multiData                          qabstractitemmodel.cpp     3681 0x7ffff69ac1df 
            6  QModelIndex::multiData                                 qabstractitemmodel.h       496  0x7ffff7c69836 
            7  QStyledItemDelegate::initStyleOption                   qstyleditemdelegate.cpp    263  0x7ffff7c69836 
            8  QStyledItemDelegate::paint                             qstyleditemdelegate.cpp    374  0x7ffff7c68ee7 
            9  QTableViewPrivate::drawCell                            qtableview.cpp             1055 0x7ffff7c947d0 
            10 QTableView::paintEvent                                 qtableview.cpp             1624 0x7ffff7c9f73c 
            11 QWidget::event                                         qwidget.cpp                9405 0x7ffff79dbaee 
            12 QFrame::event                                          qframe.cpp                 521  0x7ffff7a69ae2 
            13 QCoreApplicationPrivate::sendThroughObjectEventFilters qcoreapplication.cpp       1281 0x7ffff6762efa 
            14 QCoreApplicationPrivate::sendThroughObjectEventFilters qcoreapplication.cpp       1268 0x7ffff6762efa 
            15 QApplicationPrivate::notify_helper                     qapplication.cpp           3281 0x7ffff79844e1 
            16 QCoreApplication::notifyInternal2                      qcoreapplication.cpp       1142 0x7ffff676318a 
            17 QCoreApplication::sendSpontaneousEvent                 qcoreapplication.cpp       1597 0x7ffff6763359 
            18 QWidgetPrivate::sendPaintEvent                         qwidget.cpp                5650 0x7ffff79d35d6 
            19 QWidgetPrivate::drawWidget                             qwidget.cpp                5600 0x7ffff79d3dde 
            20 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5779 0x7ffff79d51d9 
            21 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5765 0x7ffff79d4ff8 
            22 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5765 0x7ffff79d4ff8 
            23 QWidgetPrivate::drawWidget                             qwidget.cpp                5641 0x7ffff79d3ee0 
            24 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5779 0x7ffff79d51d9 
            25 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5765 0x7ffff79d4ff8 
            26 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5765 0x7ffff79d4ff8 
            27 QWidgetPrivate::drawWidget                             qwidget.cpp                5641 0x7ffff79d3ee0 
            28 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5779 0x7ffff79d51d9 
            29 QWidgetPrivate::drawWidget                             qwidget.cpp                5641 0x7ffff79d3ee0 
            30 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5779 0x7ffff79d51d9 
            31 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5765 0x7ffff79d4ff8 
            32 QWidgetPrivate::drawWidget                             qwidget.cpp                5641 0x7ffff79d3ee0 
            33 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                5779 0x7ffff79d51d9 
            34 QWidgetPrivate::drawWidget                             qwidget.cpp                5641 0x7ffff79d3ee0 
            35 QWidgetRepaintManager::paintAndFlush                   qwidgetrepaintmanager.cpp  907  0x7ffff79e6665 
            36 QWidgetRepaintManager::sync                            qwidgetrepaintmanager.cpp  632  0x7ffff79e70bb 
            37 QWidgetWindow::event                                   qwidgetwindow.cpp          310  0x7ffff79f0818 
            38 QApplicationPrivate::notify_helper                     qapplication.cpp           3287 0x7ffff79844f2 
            39 QCoreApplication::notifyInternal2                      qcoreapplication.cpp       1142 0x7ffff676318a 
            40 QCoreApplication::sendSpontaneousEvent                 qcoreapplication.cpp       1597 0x7ffff6763359 
            41 QGuiApplicationPrivate::processExposeEvent             qguiapplication.cpp        3298 0x7ffff6fc9883 
            42 QWindowSystemInterface::sendWindowSystemEvents         qwindowsysteminterface.cpp 1114 0x7ffff702277c 
            43 xcbSourceDispatch                                      qxcbeventdispatcher.cpp    57   0x7ffff2ba2cda 
            44 ??                                                                                     0x7ffff5d94ab9 
            45 ??                                                                                     0x7ffff5df69e7 
            46 g_main_context_iteration                                                               0x7ffff5d93fc5 
            47 QEventDispatcherGlib::processEvents                    qeventdispatcher_glib.cpp  394  0x7ffff6a1a76a 
            48 QEventLoop::exec                                       qflags.h                   34   0x7ffff676e963 
            49 QCoreApplication::exec                                 qflags.h                   74   0x7ffff676b41e 
            50 main                                                   main.cpp                   10   0x55555555ee50 
            

            This?

            So it seems it crashes somewhere else in regards to the "setModel(model)". I thought it crashed there and then.

            1 Reply Last reply
            0
            • Pl45m4P Pl45m4

              Hi, the crucial parts are here

              @snubben said in tableView->setModel(model); causes SIGSEGV.:

              void DatabaseHandler::getProducts(QTableView* tableView,
              

              and then here, where it seem to crash

              tableView->setModel(model);
              

              How do you pass the view to this function? How and where do you create it?

              Also:

              if (!db.isOpen()) {
              

              This looks like you store your db connection as private member in DatabaseHandler.
              Don't do that, it might cause undefined behavior. Better use the static QSqlDatabase::database() whenever it's needed.

              snubbenS Offline
              snubbenS Offline
              snubben
              wrote on last edited by
              #8

              @Pl45m4 said in tableView->setModel(model); causes SIGSEGV.:

              Hi, the crucial parts are here

              @snubben said in tableView->setModel(model); causes SIGSEGV.:

              void DatabaseHandler::getProducts(QTableView* tableView,
              

              and then here, where it seem to crash

              tableView->setModel(model);
              

              I was wrong, it wasn't there it crashed but setting the model causes the crash.

              How do you pass the view to this function? How and where do you create it?

              I have a widgetProducts where tableViewProducts is a member.

              tableViewProducts = new QTableView(this);
              databaseHandler->getProducts(tableViewProducts, ....);
              

              Also:

              if (!db.isOpen()) {
              

              This looks like you store your db connection as private member in DatabaseHandler.
              Don't do that, it might cause undefined behavior. Better use the static QSqlDatabase::database() whenever it's needed.

              I use this:

              DatabaseHandler::DatabaseHandler(QObject *parent) : QObject(parent) {
                  db = QSqlDatabase::addDatabase("QMYSQL");
              }
              
              DatabaseHandler::~DatabaseHandler() {
                  db.close();
              }
              
              bool DatabaseHandler::openDatabase(const QString &hostname, const QString &database,
                                                 const QString &username, const QString &password, int port) {
              
                  db.setHostName(hostname);
                  db.setDatabaseName(database);
                  db.setUserName(username);
                  db.setPassword(password);
                  db.setPort(port);
                  if (!db.open()) {
                      QString message = "Error opening database. " + db.lastError().text();
                      emit sendMessage(message, 5000);
                      return false;
                  }
                  emit sendMessage("Database open", 2000);
              
                  return true;
              }
              

              OK so I set this once but not keeping a reference to "db" and use QSqlDatabase::database() to get it later?
              Why the hell is this flagged as spam???

              1 Reply Last reply
              0
              • snubbenS Offline
                snubbenS Offline
                snubben
                wrote on last edited by
                #9

                Can I have this function scope of db? A bit cleaner code.

                QSqlDatabase db = QSqlDatabase::database();
                

                I changed the code to use only QSqlDatabase::database(). Still crashing. By the way, I have another query that works with the database, difference is that I return the records in a QStringList. In case it is relevant.

                Pl45m4P 1 Reply Last reply
                0
                • Christian EhrlicherC Offline
                  Christian EhrlicherC Offline
                  Christian Ehrlicher
                  Lifetime Qt Champion
                  wrote on last edited by Christian Ehrlicher
                  #10

                  Iterate through the sqlquery results instead setting it to the model to see if it is still crashing. How did you build the Qt mysql plugin? Also I'm pretty sure query.exec() should not be called.

                  Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                  Visit the Qt Academy at https://academy.qt.io/catalog

                  snubbenS 1 Reply Last reply
                  3
                  • snubbenS snubben

                    Can I have this function scope of db? A bit cleaner code.

                    QSqlDatabase db = QSqlDatabase::database();
                    

                    I changed the code to use only QSqlDatabase::database(). Still crashing. By the way, I have another query that works with the database, difference is that I return the records in a QStringList. In case it is relevant.

                    Pl45m4P Offline
                    Pl45m4P Offline
                    Pl45m4
                    wrote on last edited by Pl45m4
                    #11

                    @snubben said in tableView->setModel(model); causes SIGSEGV.:

                    QSqlDatabase db = QSqlDatabase::database();
                    

                    I changed the code to use only QSqlDatabase::database(). Still crashing

                    I mentioned this because it's a cleaner solution. It wouldn't solve your crash issue anyway.

                    Edit:
                    As @Christian-Ehrlicher says above, the query.exec() + setQuery in combination with std::move is also weird.
                    You set execute the query, then passing a move-constructed query to the model, leaving the initial query in an undefined state.
                    (using the forum search function, you will find a lot of topics on this, like this one)

                    If I'm not mistaken setQuery will do the job for you.
                    Or you do it as shown in the QueryModel-Example.


                    If debugging is the process of removing software bugs, then programming must be the process of putting them in.

                    ~E. W. Dijkstra

                    snubbenS 1 Reply Last reply
                    0
                    • Christian EhrlicherC Christian Ehrlicher

                      Iterate through the sqlquery results instead setting it to the model to see if it is still crashing. How did you build the Qt mysql plugin? Also I'm pretty sure query.exec() should not be called.

                      snubbenS Offline
                      snubbenS Offline
                      snubben
                      wrote on last edited by snubben
                      #12

                      @Christian-Ehrlicher said in tableView->setModel(model); causes SIGSEGV.:

                      Iterate through the sqlquery results instead setting it to the model to see if it is still crashing. How did you build the Qt mysql plugin? Also I'm pretty sure query.exec() should not be called.

                      The documentation for QSqlQueryModel says

                      Resets the model and sets the data provider to be the given query. Note that the query must be active and must not be isForwardOnly().
                      

                      Apparently query.exec() makes it active:

                          qDebug() << "Is active:" << query.isActive();
                          query.exec();
                          qDebug() << "Is active:" << query.isActive();
                      
                      Is active: false
                      Is active: true
                      

                      I just did

                          query.exec();
                          while (query.next()) {
                              QString field1 = query.value(0).toString();
                              QString field2 = query.value(1).toString();
                              qDebug() << "field1:" << field1 << ", field2:" << field2;
                          }
                      

                      and it works fine.

                      I built the mysql driver using

                      mkdir ~/dev/cpp/QtBuilds/build-sqldrivers
                      cd build-sqldrivers
                      qt-cmake -G Ninja ~/Qt/6.7.2/Src/qtbase/src/plugins/sqldrivers -DCMAKE_INSTALL_PREFIX="~/Qt/6.7.2/Src" -DMySQL_INCLUDE_DIR="/usr/include/mysql" -DMySQL_LIBRARY="/usr/lib/libmysqlclient.so"
                      cmake --build .
                      cmake --install .
                      

                      and it didn't report errors.
                      In my application I have this so it finds the driver. This is the folder that "cmake --install ." installed to.

                      QCoreApplication::addLibraryPath("/home/username/Qt/6.7.2/Src/lib/qt6/plugins");
                      

                      @Christian-Ehrlicher said in tableView->setModel(model); causes SIGSEGV.:

                      Or you do it as shown in the QueryModel-Example.

                      Yes, a simple QString query like that works. But I need to search based on search criterias, thus the dynamic SQL. I haven't found that it is possible to bind values to the model.

                      1 Reply Last reply
                      0
                      • Pl45m4P Pl45m4

                        @snubben said in tableView->setModel(model); causes SIGSEGV.:

                        QSqlDatabase db = QSqlDatabase::database();
                        

                        I changed the code to use only QSqlDatabase::database(). Still crashing

                        I mentioned this because it's a cleaner solution. It wouldn't solve your crash issue anyway.

                        Edit:
                        As @Christian-Ehrlicher says above, the query.exec() + setQuery in combination with std::move is also weird.
                        You set execute the query, then passing a move-constructed query to the model, leaving the initial query in an undefined state.
                        (using the forum search function, you will find a lot of topics on this, like this one)

                        If I'm not mistaken setQuery will do the job for you.
                        Or you do it as shown in the QueryModel-Example.

                        snubbenS Offline
                        snubbenS Offline
                        snubben
                        wrote on last edited by
                        #13

                        @Pl45m4 said in tableView->setModel(model); causes SIGSEGV.:

                        @snubben said in tableView->setModel(model); causes SIGSEGV.:

                        QSqlDatabase db = QSqlDatabase::database();
                        

                        I changed the code to use only QSqlDatabase::database(). Still crashing

                        I mentioned this because it's a cleaner solution. It wouldn't solve your crash issue anyway.

                        Edit:
                        As @Christian-Ehrlicher says above, the query.exec() + setQuery in combination with std::move is also weird.
                        You set execute the query, then passing a move-constructed query to the model, leaving the initial query in an undefined state.
                        (using the forum search function, you will find a lot of topics on this, like this one)

                        If I'm not mistaken setQuery will do the job for you.
                        Or you do it as shown in the QueryModel-Example.

                        If I use

                        model->setQuery("select * from products");
                        

                        it works. It shows the data. But I cannot bind variables then. Again, I am 100% new to C++/Qt so might miss some fundamental principle on how to achieve this.

                        I see from the thread you linked that the query.exec(), std::move is also used there.

                        JonBJ 1 Reply Last reply
                        0
                        • snubbenS snubben

                          @Pl45m4 said in tableView->setModel(model); causes SIGSEGV.:

                          @snubben said in tableView->setModel(model); causes SIGSEGV.:

                          QSqlDatabase db = QSqlDatabase::database();
                          

                          I changed the code to use only QSqlDatabase::database(). Still crashing

                          I mentioned this because it's a cleaner solution. It wouldn't solve your crash issue anyway.

                          Edit:
                          As @Christian-Ehrlicher says above, the query.exec() + setQuery in combination with std::move is also weird.
                          You set execute the query, then passing a move-constructed query to the model, leaving the initial query in an undefined state.
                          (using the forum search function, you will find a lot of topics on this, like this one)

                          If I'm not mistaken setQuery will do the job for you.
                          Or you do it as shown in the QueryModel-Example.

                          If I use

                          model->setQuery("select * from products");
                          

                          it works. It shows the data. But I cannot bind variables then. Again, I am 100% new to C++/Qt so might miss some fundamental principle on how to achieve this.

                          I see from the thread you linked that the query.exec(), std::move is also used there.

                          JonBJ Offline
                          JonBJ Offline
                          JonB
                          wrote on last edited by JonB
                          #14

                          @snubben said in tableView->setModel(model); causes SIGSEGV.:

                          it works. It shows the data.

                          So now per your earlier debug information try the actual query which seems to be executed with your bindings:

                          SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;
                          

                          How does that fare?

                          If that works standalone, next try that as a literal for your model, this way:

                          QSqlQueryModel* model = new QSqlQueryModel(this);
                          model->setQuery("SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;");
                          

                          How does that fare?

                          snubbenS 1 Reply Last reply
                          0
                          • JonBJ JonB

                            @snubben said in tableView->setModel(model); causes SIGSEGV.:

                            it works. It shows the data.

                            So now per your earlier debug information try the actual query which seems to be executed with your bindings:

                            SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;
                            

                            How does that fare?

                            If that works standalone, next try that as a literal for your model, this way:

                            QSqlQueryModel* model = new QSqlQueryModel(this);
                            model->setQuery("SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;");
                            

                            How does that fare?

                            snubbenS Offline
                            snubbenS Offline
                            snubben
                            wrote on last edited by snubben
                            #15

                            @JonB said in tableView->setModel(model); causes SIGSEGV.:

                            @snubben said in tableView->setModel(model); causes SIGSEGV.:

                            it works. It shows the data.

                            So now per your earlier debug information try the actual query which seems to be executed with your bindings:

                            SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;
                            

                            How does that fare?

                            If that works standalone, next try that as a literal for your model, this way:

                            QSqlQueryModel* model = new QSqlQueryModel(this);
                            model->setQuery("SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;");
                            

                            How does that fare?

                            Yes, all those work! How to I apply search criterias if I use a QString query?

                            1 Reply Last reply
                            0
                            • snubbenS Offline
                              snubbenS Offline
                              snubben
                              wrote on last edited by snubben
                              #16

                              So I debugged some more and if I understand correctly it seg faults in qsql_mysql.cpp at

                              bool QMYSQLResult::fetch(int i)
                              {
                                  Q_D(QMYSQLResult);
                                  if (!driver())
                                      return false;
                                  if (isForwardOnly()) { // fake a forward seek
                                      if (at() < i) {
                                          int x = i - at();
                                          while (--x && fetchNext()) {};
                                          return fetchNext();
                                      } else {
                                          return false;
                                      }
                                  }
                                  if (at() == i)
                                      return true;
                                  if (d->preparedQuery) {
                                      mysql_stmt_data_seek(d->stmt, i);
                              
                                      int nRC = mysql_stmt_fetch(d->stmt); <<<< HERE SEG FAULT
                                      if (nRC) {
                                          if (nRC == 1 || nRC == MYSQL_DATA_TRUNCATED)
                                              setLastError(qMakeStmtError(QCoreApplication::translate("QMYSQLResult",
                                                       "Unable to fetch data"), QSqlError::StatementError, d->stmt));
                                          return false;
                                      }
                                  } else {
                                      mysql_data_seek(d->result, i);
                                      d->row = mysql_fetch_row(d->result);
                                      if (!d->row)
                                          return false;
                                  }
                              
                                  setAt(i);
                                  return true;
                              }
                              

                              d pointer has the following information:

                              	*d	@0x5555557afe10	QMYSQLResultPrivate
                              		[QSqlResultPrivate]	<not accessible>	QSqlResultPrivate
                              		fields	<5 items>	QList<QMYSQLResultPrivate::QMyField>
                              			[0]	@0x55555573e930	QMYSQLResultPrivate::QMyField
                              				bufLength	401	ulong
                              				*myField	@0x555555929d88	MYSQL_FIELD
                              					catalog	"def"	char *
                              					catalog_length	3	unsigned int
                              					charsetnr	45	unsigned int
                              					db	"database_name"	char *
                              					db_length	9	unsigned int
                              					decimals	0	unsigned int
                              					def	0x0	char *
                              					def_length	0	unsigned int
                              					extension	0x0	void *
                              					flags	20483	unsigned int
                              					length	400	unsigned long
                              					max_length	0	unsigned long
                              					name	"field1"	char *
                              					name_length	7	unsigned int
                              					org_name	"field1"	char *
                              					org_name_length	7	unsigned int
                              					org_table	"products"	char *
                              					org_table_length	11	unsigned int
                              					table	"products"	char *
                              					table_length	11	unsigned int
                              					type	MYSQL_TYPE_VAR_STRING (253)	enum_field_types
                              				nullIndicator	0	my_bool
                              				outField	""	char *
                              				type	@0x55555573e940	QMetaType
                              			[1]	@0x55555573e958	QMYSQLResultPrivate::QMyField
                              				bufLength	401	ulong
                              				*myField	@0x555555929e08	MYSQL_FIELD
                              					catalog	"def"	char *
                              					catalog_length	3	unsigned int
                              					charsetnr	45	unsigned int
                              					db	"database_name"	char *
                              					db_length	9	unsigned int
                              					decimals	0	unsigned int
                              					def	0x0	char *
                              					def_length	0	unsigned int
                              					extension	0x0	void *
                              					flags	4097	unsigned int
                              					length	400	unsigned long
                              					max_length	0	unsigned long
                              					name	"name"	char *
                              					name_length	4	unsigned int
                              					org_name	"name"	char *
                              					org_name_length	4	unsigned int
                              					org_table	"products"	char *
                              					org_table_length	11	unsigned int
                              					table	"products"	char *
                              					table_length	11	unsigned int
                              					type	MYSQL_TYPE_VAR_STRING (253)	enum_field_types
                              				nullIndicator	0	my_bool
                              				outField	""	char *
                              				type	@0x55555573e968	QMetaType
                              			[2]	@0x55555573e980	QMYSQLResultPrivate::QMyField
                              				bufLength	4	ulong
                              				*myField	@0x555555929e88	MYSQL_FIELD
                              					catalog	"def"	char *
                              					catalog_length	3	unsigned int
                              					charsetnr	63	unsigned int
                              					db	"database_name"	char *
                              					db_length	9	unsigned int
                              					decimals	0	unsigned int
                              					def	0x0	char *
                              					def_length	0	unsigned int
                              					extension	0x0	void *
                              					flags	36865	unsigned int
                              					length	11	unsigned long
                              					max_length	0	unsigned long
                              					name	"prodCount"	char *
                              					name_length	5	unsigned int
                              					org_name	"prodCount"	char *
                              					org_name_length	10	unsigned int
                              					org_table	"products"	char *
                              					org_table_length	11	unsigned int
                              					table	"products"	char *
                              					table_length	11	unsigned int
                              					type	MYSQL_TYPE_LONG (3)	enum_field_types
                              				nullIndicator	0	my_bool
                              				outField	""	char *
                              				type	@0x55555573e990	QMetaType
                              			[3]	@0x55555573e9a8	QMYSQLResultPrivate::QMyField
                              				bufLength	401	ulong
                              				*myField	@0x555555929f08	MYSQL_FIELD
                              					catalog	"def"	char *
                              					catalog_length	3	unsigned int
                              					charsetnr	45	unsigned int
                              					db	"database_name"	char *
                              					db_length	9	unsigned int
                              					decimals	0	unsigned int
                              					def	0x0	char *
                              					def_length	0	unsigned int
                              					extension	0x0	void *
                              					flags	4097	unsigned int
                              					length	400	unsigned long
                              					max_length	0	unsigned long
                              					name	"field3"	char *
                              					name_length	4	unsigned int
                              					org_name	"field3"	char *
                              					org_name_length	17	unsigned int
                              					org_table	"products"	char *
                              					org_table_length	11	unsigned int
                              					table	"products"	char *
                              					table_length	11	unsigned int
                              					type	MYSQL_TYPE_VAR_STRING (253)	enum_field_types
                              				nullIndicator	0	my_bool
                              				outField	""	char *
                              				type	@0x55555573e9b8	QMetaType
                              			[4]	@0x55555573e9d0	QMYSQLResultPrivate::QMyField
                              				bufLength	40	ulong
                              				*myField	@0x555555929f88	MYSQL_FIELD
                              					catalog	"def"	char *
                              					catalog_length	3	unsigned int
                              					charsetnr	63	unsigned int
                              					db	"database_name"	char *
                              					db_length	9	unsigned int
                              					decimals	0	unsigned int
                              					def	0x0	char *
                              					def_length	0	unsigned int
                              					extension	0x0	void *
                              					flags	128	unsigned int
                              					length	10	unsigned long
                              					max_length	0	unsigned long
                              					name	"dateMin"	char *
                              					name_length	8	unsigned int
                              					org_name	"dateMin"	char *
                              					org_name_length	8	unsigned int
                              					org_table	"products"	char *
                              					org_table_length	11	unsigned int
                              					table	"products"	char *
                              					table_length	11	unsigned int
                              					type	MYSQL_TYPE_DATE (10)	enum_field_types
                              				nullIndicator	0	my_bool
                              				outField	""	char *
                              				type	@0x55555573e9e0	QMetaType
                              		hasBlobs	false	bool
                              		*inBinds	@0x5555557ce380	MYSQL_BIND
                              			buffer	0x5555556f1d30	void *
                              			buffer_length	401	unsigned long
                              			buffer_type	MYSQL_TYPE_STRING (254)	enum_field_types
                              			error	0x0	my_bool *
                              			error_value	0	my_bool
                              			extension	0x0	void *
                              			fetch_result	0x0	void (st_mysql_bind *, MYSQL_FIELD *, unsigned char * *) *
                              			flags	0	unsigned int
                              			is_null	""	my_bool *
                              			is_null_value	0	my_bool
                              			is_unsigned	0	my_bool
                              			*length	401	unsigned long
                              			length_value	0	unsigned long
                              			long_data_used	0	my_bool
                              			offset	0	unsigned long
                              			pack_length	0	unsigned int
                              			skip_result	0x0	void (st_mysql_bind *, MYSQL_FIELD *, unsigned char * *) *
                              			store_param_func	0x0	void (NET *, st_mysql_bind *) *
                              			u	@0x5555557ce3a0	union {...}
                              				indicator	0x0	char *
                              				row_ptr	0x0	unsigned char *
                              		*meta	@0x5555556eedf0	MYSQL_RES
                              			current_field	0	unsigned int
                              			current_row	0	MYSQL_ROW
                              			data	0x0	MYSQL_DATA *
                              			data_cursor	0x0	MYSQL_ROWS *
                              			eof	1	my_bool
                              			field_alloc	@0x5555556eee18	MA_MEM_ROOT
                              			field_count	5	unsigned int
                              			*fields	@0x555555929d88	MYSQL_FIELD
                              			handle	0x0	MYSQL *
                              			is_ps	0	my_bool
                              			lengths	0x0	unsigned long *
                              			row	0	MYSQL_ROW
                              			row_count	0	unsigned long long
                              		outBinds	0x0	MYSQL_BIND *
                              		preparedQuery	true	bool
                              		result	0x0	MYSQL_RES *
                              		row	0	MYSQL_ROW
                              		rowsAffected	-1	int
                              		*stmt	@0x5555556c81a0	MYSQL_STMT
                              			array_size	0	unsigned int
                              			*bind	@0x55555592a198	MYSQL_BIND
                              			bind_param_done	0	my_bool
                              			bind_result_done	1	my_bool
                              			cursor_exists	0	my_bool
                              			default_rset_handler	0x7ffff0cf5880 <mysql_next_result+224>	mysql_stmt_use_or_store_func
                              			execute_count	1	unsigned int
                              			extension	0x5555556a9700	void *
                              			fetch_row_func	140737233504192	mysql_stmt_fetch_row_func
                              			field_count	5	unsigned int
                              			*fields	@0x555555929d88	MYSQL_FIELD
                              			flags	0	unsigned long
                              			last_errno	0	unsigned int
                              			last_error	"\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000..."	char[513] of length 513
                              			list	@0x5555556c84c0	LIST
                              			mem_root	@0x5555556c81a0	MA_MEM_ROOT
                              			*mysql	@0x5555556a8280	MYSQL
                              			param_callback	0	ps_param_callback
                              			param_count	0	unsigned int
                              			params	0x0	MYSQL_BIND *
                              			prebind_params	0	unsigned int
                              			prefetch_rows	1	unsigned long
                              			request_buffer	0x0	unsigned char *
                              			request_length	0	size_t
                              			result	@0x5555556c8220	MYSQL_DATA
                              			result_callback	0	ps_result_callback
                              			*result_cursor	@0x55555590fa68	MYSQL_ROWS
                              			row_size	0	size_t
                              			send_types_to_server	'\0'	0	0x00	unsigned char
                              			sqlstate	"00000\000"	char[6] of length 6
                              			state	MYSQL_STMT_USER_FETCHING (5)	enum_mysqlnd_stmt_state
                              			stmt_id	18	unsigned long
                              			update_max_length	0	my_bool
                              			upsert_status	@0x5555556c8290	mysql_upsert_status
                              			user_data	0x0	void *
                              
                              

                              I have anonymized the SQL and database information, therefore the field name lengths do not match.

                              JonBJ 1 Reply Last reply
                              0
                              • Christian EhrlicherC Offline
                                Christian EhrlicherC Offline
                                Christian Ehrlicher
                                Lifetime Qt Champion
                                wrote on last edited by
                                #17

                                You should really strip this down to a minimal, compileable example. Simply open a db connection, create and fill a table and set the query to the model. Modify it to your use case until it is crashing or you can see what you are doing wrong.

                                Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                                Visit the Qt Academy at https://academy.qt.io/catalog

                                1 Reply Last reply
                                0
                                • snubbenS snubben

                                  So I debugged some more and if I understand correctly it seg faults in qsql_mysql.cpp at

                                  bool QMYSQLResult::fetch(int i)
                                  {
                                      Q_D(QMYSQLResult);
                                      if (!driver())
                                          return false;
                                      if (isForwardOnly()) { // fake a forward seek
                                          if (at() < i) {
                                              int x = i - at();
                                              while (--x && fetchNext()) {};
                                              return fetchNext();
                                          } else {
                                              return false;
                                          }
                                      }
                                      if (at() == i)
                                          return true;
                                      if (d->preparedQuery) {
                                          mysql_stmt_data_seek(d->stmt, i);
                                  
                                          int nRC = mysql_stmt_fetch(d->stmt); <<<< HERE SEG FAULT
                                          if (nRC) {
                                              if (nRC == 1 || nRC == MYSQL_DATA_TRUNCATED)
                                                  setLastError(qMakeStmtError(QCoreApplication::translate("QMYSQLResult",
                                                           "Unable to fetch data"), QSqlError::StatementError, d->stmt));
                                              return false;
                                          }
                                      } else {
                                          mysql_data_seek(d->result, i);
                                          d->row = mysql_fetch_row(d->result);
                                          if (!d->row)
                                              return false;
                                      }
                                  
                                      setAt(i);
                                      return true;
                                  }
                                  

                                  d pointer has the following information:

                                  	*d	@0x5555557afe10	QMYSQLResultPrivate
                                  		[QSqlResultPrivate]	<not accessible>	QSqlResultPrivate
                                  		fields	<5 items>	QList<QMYSQLResultPrivate::QMyField>
                                  			[0]	@0x55555573e930	QMYSQLResultPrivate::QMyField
                                  				bufLength	401	ulong
                                  				*myField	@0x555555929d88	MYSQL_FIELD
                                  					catalog	"def"	char *
                                  					catalog_length	3	unsigned int
                                  					charsetnr	45	unsigned int
                                  					db	"database_name"	char *
                                  					db_length	9	unsigned int
                                  					decimals	0	unsigned int
                                  					def	0x0	char *
                                  					def_length	0	unsigned int
                                  					extension	0x0	void *
                                  					flags	20483	unsigned int
                                  					length	400	unsigned long
                                  					max_length	0	unsigned long
                                  					name	"field1"	char *
                                  					name_length	7	unsigned int
                                  					org_name	"field1"	char *
                                  					org_name_length	7	unsigned int
                                  					org_table	"products"	char *
                                  					org_table_length	11	unsigned int
                                  					table	"products"	char *
                                  					table_length	11	unsigned int
                                  					type	MYSQL_TYPE_VAR_STRING (253)	enum_field_types
                                  				nullIndicator	0	my_bool
                                  				outField	""	char *
                                  				type	@0x55555573e940	QMetaType
                                  			[1]	@0x55555573e958	QMYSQLResultPrivate::QMyField
                                  				bufLength	401	ulong
                                  				*myField	@0x555555929e08	MYSQL_FIELD
                                  					catalog	"def"	char *
                                  					catalog_length	3	unsigned int
                                  					charsetnr	45	unsigned int
                                  					db	"database_name"	char *
                                  					db_length	9	unsigned int
                                  					decimals	0	unsigned int
                                  					def	0x0	char *
                                  					def_length	0	unsigned int
                                  					extension	0x0	void *
                                  					flags	4097	unsigned int
                                  					length	400	unsigned long
                                  					max_length	0	unsigned long
                                  					name	"name"	char *
                                  					name_length	4	unsigned int
                                  					org_name	"name"	char *
                                  					org_name_length	4	unsigned int
                                  					org_table	"products"	char *
                                  					org_table_length	11	unsigned int
                                  					table	"products"	char *
                                  					table_length	11	unsigned int
                                  					type	MYSQL_TYPE_VAR_STRING (253)	enum_field_types
                                  				nullIndicator	0	my_bool
                                  				outField	""	char *
                                  				type	@0x55555573e968	QMetaType
                                  			[2]	@0x55555573e980	QMYSQLResultPrivate::QMyField
                                  				bufLength	4	ulong
                                  				*myField	@0x555555929e88	MYSQL_FIELD
                                  					catalog	"def"	char *
                                  					catalog_length	3	unsigned int
                                  					charsetnr	63	unsigned int
                                  					db	"database_name"	char *
                                  					db_length	9	unsigned int
                                  					decimals	0	unsigned int
                                  					def	0x0	char *
                                  					def_length	0	unsigned int
                                  					extension	0x0	void *
                                  					flags	36865	unsigned int
                                  					length	11	unsigned long
                                  					max_length	0	unsigned long
                                  					name	"prodCount"	char *
                                  					name_length	5	unsigned int
                                  					org_name	"prodCount"	char *
                                  					org_name_length	10	unsigned int
                                  					org_table	"products"	char *
                                  					org_table_length	11	unsigned int
                                  					table	"products"	char *
                                  					table_length	11	unsigned int
                                  					type	MYSQL_TYPE_LONG (3)	enum_field_types
                                  				nullIndicator	0	my_bool
                                  				outField	""	char *
                                  				type	@0x55555573e990	QMetaType
                                  			[3]	@0x55555573e9a8	QMYSQLResultPrivate::QMyField
                                  				bufLength	401	ulong
                                  				*myField	@0x555555929f08	MYSQL_FIELD
                                  					catalog	"def"	char *
                                  					catalog_length	3	unsigned int
                                  					charsetnr	45	unsigned int
                                  					db	"database_name"	char *
                                  					db_length	9	unsigned int
                                  					decimals	0	unsigned int
                                  					def	0x0	char *
                                  					def_length	0	unsigned int
                                  					extension	0x0	void *
                                  					flags	4097	unsigned int
                                  					length	400	unsigned long
                                  					max_length	0	unsigned long
                                  					name	"field3"	char *
                                  					name_length	4	unsigned int
                                  					org_name	"field3"	char *
                                  					org_name_length	17	unsigned int
                                  					org_table	"products"	char *
                                  					org_table_length	11	unsigned int
                                  					table	"products"	char *
                                  					table_length	11	unsigned int
                                  					type	MYSQL_TYPE_VAR_STRING (253)	enum_field_types
                                  				nullIndicator	0	my_bool
                                  				outField	""	char *
                                  				type	@0x55555573e9b8	QMetaType
                                  			[4]	@0x55555573e9d0	QMYSQLResultPrivate::QMyField
                                  				bufLength	40	ulong
                                  				*myField	@0x555555929f88	MYSQL_FIELD
                                  					catalog	"def"	char *
                                  					catalog_length	3	unsigned int
                                  					charsetnr	63	unsigned int
                                  					db	"database_name"	char *
                                  					db_length	9	unsigned int
                                  					decimals	0	unsigned int
                                  					def	0x0	char *
                                  					def_length	0	unsigned int
                                  					extension	0x0	void *
                                  					flags	128	unsigned int
                                  					length	10	unsigned long
                                  					max_length	0	unsigned long
                                  					name	"dateMin"	char *
                                  					name_length	8	unsigned int
                                  					org_name	"dateMin"	char *
                                  					org_name_length	8	unsigned int
                                  					org_table	"products"	char *
                                  					org_table_length	11	unsigned int
                                  					table	"products"	char *
                                  					table_length	11	unsigned int
                                  					type	MYSQL_TYPE_DATE (10)	enum_field_types
                                  				nullIndicator	0	my_bool
                                  				outField	""	char *
                                  				type	@0x55555573e9e0	QMetaType
                                  		hasBlobs	false	bool
                                  		*inBinds	@0x5555557ce380	MYSQL_BIND
                                  			buffer	0x5555556f1d30	void *
                                  			buffer_length	401	unsigned long
                                  			buffer_type	MYSQL_TYPE_STRING (254)	enum_field_types
                                  			error	0x0	my_bool *
                                  			error_value	0	my_bool
                                  			extension	0x0	void *
                                  			fetch_result	0x0	void (st_mysql_bind *, MYSQL_FIELD *, unsigned char * *) *
                                  			flags	0	unsigned int
                                  			is_null	""	my_bool *
                                  			is_null_value	0	my_bool
                                  			is_unsigned	0	my_bool
                                  			*length	401	unsigned long
                                  			length_value	0	unsigned long
                                  			long_data_used	0	my_bool
                                  			offset	0	unsigned long
                                  			pack_length	0	unsigned int
                                  			skip_result	0x0	void (st_mysql_bind *, MYSQL_FIELD *, unsigned char * *) *
                                  			store_param_func	0x0	void (NET *, st_mysql_bind *) *
                                  			u	@0x5555557ce3a0	union {...}
                                  				indicator	0x0	char *
                                  				row_ptr	0x0	unsigned char *
                                  		*meta	@0x5555556eedf0	MYSQL_RES
                                  			current_field	0	unsigned int
                                  			current_row	0	MYSQL_ROW
                                  			data	0x0	MYSQL_DATA *
                                  			data_cursor	0x0	MYSQL_ROWS *
                                  			eof	1	my_bool
                                  			field_alloc	@0x5555556eee18	MA_MEM_ROOT
                                  			field_count	5	unsigned int
                                  			*fields	@0x555555929d88	MYSQL_FIELD
                                  			handle	0x0	MYSQL *
                                  			is_ps	0	my_bool
                                  			lengths	0x0	unsigned long *
                                  			row	0	MYSQL_ROW
                                  			row_count	0	unsigned long long
                                  		outBinds	0x0	MYSQL_BIND *
                                  		preparedQuery	true	bool
                                  		result	0x0	MYSQL_RES *
                                  		row	0	MYSQL_ROW
                                  		rowsAffected	-1	int
                                  		*stmt	@0x5555556c81a0	MYSQL_STMT
                                  			array_size	0	unsigned int
                                  			*bind	@0x55555592a198	MYSQL_BIND
                                  			bind_param_done	0	my_bool
                                  			bind_result_done	1	my_bool
                                  			cursor_exists	0	my_bool
                                  			default_rset_handler	0x7ffff0cf5880 <mysql_next_result+224>	mysql_stmt_use_or_store_func
                                  			execute_count	1	unsigned int
                                  			extension	0x5555556a9700	void *
                                  			fetch_row_func	140737233504192	mysql_stmt_fetch_row_func
                                  			field_count	5	unsigned int
                                  			*fields	@0x555555929d88	MYSQL_FIELD
                                  			flags	0	unsigned long
                                  			last_errno	0	unsigned int
                                  			last_error	"\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000..."	char[513] of length 513
                                  			list	@0x5555556c84c0	LIST
                                  			mem_root	@0x5555556c81a0	MA_MEM_ROOT
                                  			*mysql	@0x5555556a8280	MYSQL
                                  			param_callback	0	ps_param_callback
                                  			param_count	0	unsigned int
                                  			params	0x0	MYSQL_BIND *
                                  			prebind_params	0	unsigned int
                                  			prefetch_rows	1	unsigned long
                                  			request_buffer	0x0	unsigned char *
                                  			request_length	0	size_t
                                  			result	@0x5555556c8220	MYSQL_DATA
                                  			result_callback	0	ps_result_callback
                                  			*result_cursor	@0x55555590fa68	MYSQL_ROWS
                                  			row_size	0	size_t
                                  			send_types_to_server	'\0'	0	0x00	unsigned char
                                  			sqlstate	"00000\000"	char[6] of length 6
                                  			state	MYSQL_STMT_USER_FETCHING (5)	enum_mysqlnd_stmt_state
                                  			stmt_id	18	unsigned long
                                  			update_max_length	0	my_bool
                                  			upsert_status	@0x5555556c8290	mysql_upsert_status
                                  			user_data	0x0	void *
                                  
                                  

                                  I have anonymized the SQL and database information, therefore the field name lengths do not match.

                                  JonBJ Offline
                                  JonBJ Offline
                                  JonB
                                  wrote on last edited by JonB
                                  #18

                                  @snubben
                                  As @Christian-Ehrlicher says.

                                  Given that you say

                                  QSqlQueryModel* model = new QSqlQueryModel(this);
                                  model->setQuery("SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;");
                                  

                                  does work I am not sure where your actual example differs significantly from this. Try it now the way you do it as

                                  QSqlQueryModel* model = new QSqlQueryModel(this);
                                  QSqlQuery query(db);
                                  query.prepare("SELECT field1, field2, prodCount, field3, prod_date  FROM products WHERE 1 = 1 ORDER BY prod_date DESC;");
                                  model->setQuery(query);
                                  

                                  I have not included your std::move() not your query.exec();. Only add those in if it does not work as is. See where you get to. If you get that working I'm sure you can then start introducing parameter bindings.

                                  At some point you ought get rid of that QSqlDatabase db class member variable. Per the docs you should be using the static QSqlDatabase QSqlDatabase::database() for that instead. I don't know whether it might be relevant here, probably not but you never know.

                                  1 Reply Last reply
                                  0
                                  • snubbenS Offline
                                    snubbenS Offline
                                    snubben
                                    wrote on last edited by snubben
                                    #19

                                    It works!

                                    QSqlTableModel* model = new QSqlTableModel(this);
                                    

                                    Using this it works. I must read more about QSqlQueryModel and why it didn't work in this situation.
                                    Thank you all!

                                    JonBJ 1 Reply Last reply
                                    0
                                    • snubbenS snubben has marked this topic as solved on
                                    • snubbenS snubben

                                      It works!

                                      QSqlTableModel* model = new QSqlTableModel(this);
                                      

                                      Using this it works. I must read more about QSqlQueryModel and why it didn't work in this situation.
                                      Thank you all!

                                      JonBJ Offline
                                      JonBJ Offline
                                      JonB
                                      wrote on last edited by JonB
                                      #20

                                      @snubben said in tableView->setModel(model); causes SIGSEGV.:

                                      Using this it works.

                                      @Christian-Ehrlicher
                                      OP reports that QSqlTableModel works for his QTableView but not QSqlQueryModel. I wonder why? QTV only requires a QAbstractItemModel, QSqlTableModel inherits from QSqlQueryModel, why should the latter not work?

                                      The model for QTV must not be forward-only. Is QSqlQueryModel perhaps automatically forward-only, is that an issue?

                                      UPDATE
                                      Non-issue, see further posts below.

                                      1 Reply Last reply
                                      1
                                      • snubbenS Offline
                                        snubbenS Offline
                                        snubben
                                        wrote on last edited by
                                        #21

                                        This works too!

                                        QSqlQueryModel* model = new QSqlQueryModel(this);
                                        

                                        I feel like a complete moron. I had to check git and in an other function where I get strings for a QComboBox I had

                                            if (!QSqlDatabase::database().open()) {
                                                qCritical() << "Database connection failed:" << QSqlDatabase::database().lastError().text();
                                                //emit errorOccurred(db.lastError().text());
                                                return result;
                                            }
                                        

                                        which should have of course been

                                        if (!QSqlDatabase::database().isOpen()) {
                                        

                                        and this I changed without even reflecting upon it.
                                        A lot I need to learn to properly find the erring location with Qt Creator. Once again, thanks guys & girls!

                                        JonBJ 1 Reply Last reply
                                        0
                                        • snubbenS snubben

                                          This works too!

                                          QSqlQueryModel* model = new QSqlQueryModel(this);
                                          

                                          I feel like a complete moron. I had to check git and in an other function where I get strings for a QComboBox I had

                                              if (!QSqlDatabase::database().open()) {
                                                  qCritical() << "Database connection failed:" << QSqlDatabase::database().lastError().text();
                                                  //emit errorOccurred(db.lastError().text());
                                                  return result;
                                              }
                                          

                                          which should have of course been

                                          if (!QSqlDatabase::database().isOpen()) {
                                          

                                          and this I changed without even reflecting upon it.
                                          A lot I need to learn to properly find the erring location with Qt Creator. Once again, thanks guys & girls!

                                          JonBJ Offline
                                          JonBJ Offline
                                          JonB
                                          wrote on last edited by JonB
                                          #22

                                          @snubben said in tableView->setModel(model); causes SIGSEGV.:

                                          This works too!

                                          QSqlQueryModel* model = new QSqlQueryModel(this);

                                          Huh? That is what you started with right at the beginning:

                                          QSqlQueryModel* model = new QSqlQueryModel(this);

                                          That's from your first post. So if you're not saying you had to change from a QSqlQueryModel to a QSqlTableModel per your previous post --- and like I write to @Christian-Ehrlicher I don;t see why you should have to --- then I don't understand what you think you changed to make it work.

                                          snubbenS 1 Reply Last reply
                                          0

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