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QTableview data disappear..

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  • SGaistS SGaist

    Hi,

    Are you reseting the database connection ?

    TheCipo76T Offline
    TheCipo76T Offline
    TheCipo76
    wrote on last edited by TheCipo76
    #3

    @SGaist no but i have found in "Application Output":

    QSqlDatabasePrivate::removeDatabase: connection 'qt_sql_default_connection' is still in use, all queries will cease to work.
    QSqlDatabasePrivate::addDatabase: duplicate connection name 'qt_sql_default_connection', old connection removed.

    i've put DB declaration and DB.close() within brakets, than out of brakets, called:

    QSqlDatabase::removeDatabase("QMYSQL");

    but warning still remain..

    Note that i can't use:

    QSqlDatabase db = QSqlDatabase::database("dbname"); --> give me this error: Driver not loaded

    but i'm using

    QSqlDatabase mDatabase = QSqlDatabase::addDatabase("dbname"); --> run correctly

    1 Reply Last reply
    0
    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #4

      Can you show exactly how you are handling QSqlDatabase in your application ?

      Because it looks like you are either keeping local objects of that type or adding and removing the connection in several different unsynchronised parts of your application.

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

      TheCipo76T 1 Reply Last reply
      1
      • SGaistS SGaist

        Can you show exactly how you are handling QSqlDatabase in your application ?

        Because it looks like you are either keeping local objects of that type or adding and removing the connection in several different unsynchronised parts of your application.

        TheCipo76T Offline
        TheCipo76T Offline
        TheCipo76
        wrote on last edited by TheCipo76
        #5

        @SGaist this is a dialog who show data from DB in a QTableView

        #include "statoordini.h"
        #include "ui_statoordini.h"
        #include "QtSql"
        #include "QtDebug"
        //#include <QSqlTableModel>
        #include <QSqlError>
        #include <QMessageBox>
        
        
        StatoOrdini::StatoOrdini(QWidget *parent, const QString &Utente, const QString &Password) :
            QDialog(parent),
            ui(new Ui::StatoOrdini),
            Utente(Utente),
            Password(Password)
        {
            ui->setupUi(this);
        
            //qputenv("QT_DEBUG_PLUGINS", QByteArray("1"));
        
            {
                QSqlDatabase mDatabase = QSqlDatabase::addDatabase("QMYSQL");
                //localhost
                mDatabase.setHostName("192.168.1.250");
                //3306
                mDatabase.setPort(3307);
                mDatabase.setDatabaseName("MISSORA");
                mDatabase.setUserName(Utente);
                mDatabase.setPassword(Password);
                if (!mDatabase.open()) {
                    QMessageBox::critical(this, "Error", mDatabase.lastError().text());
                    return;
                };
            
                QSqlTableModel *mModel = new QSqlTableModel(this);
                mModel->setTable("ORDINI");
                mModel->select();
                ui->tableView->setModel(mModel);
                // Ordina al click su Header
                ui->tableView->setSortingEnabled(true);
                ui->tableView->horizontalHeader()->setSectionsClickable(1);
                // Ridimensiona Colonne tableView al Contenuto
                ui->tableView->horizontalHeader()->setSectionResizeMode(QHeaderView::ResizeToContents);
                ui->tableView->setColumnHidden(0,true);
                ui->tableView->setEditTriggers(QAbstractItemView::NoEditTriggers);
                ui->tableView->show();
            
                QString Name = mDatabase.connectionName();
                QMessageBox msg;
                msg.setText(Name);
                msg.exec();
                mDatabase.close();
            }
            QSqlDatabase::removeDatabase("QMYSQL");
        }
        
        StatoOrdini::~StatoOrdini()
        {
            //qt_sql_default_connection;
            //QSqlDatabase::removeDatabase("QMYSQL");
        
            delete ui;
        }
        
        
        
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        • Christian EhrlicherC Offline
          Christian EhrlicherC Offline
          Christian Ehrlicher
          Lifetime Qt Champion
          wrote on last edited by
          #6

          @TheCipo76 said in QTableview data disappear..:

          mDatabase.close();

          How should this work? A QSqlModel needs access to the database at any time...

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

          TheCipo76T 1 Reply Last reply
          1
          • Christian EhrlicherC Christian Ehrlicher

            @TheCipo76 said in QTableview data disappear..:

            mDatabase.close();

            How should this work? A QSqlModel needs access to the database at any time...

            TheCipo76T Offline
            TheCipo76T Offline
            TheCipo76
            wrote on last edited by
            #7

            @Christian-Ehrlicher as you see lower..

            0_1545298637152_Schermata 2018-12-20 alle 10.35.51.png

            works!

            1 Reply Last reply
            0
            • Christian EhrlicherC Offline
              Christian EhrlicherC Offline
              Christian Ehrlicher
              Lifetime Qt Champion
              wrote on last edited by
              #8

              It works as long as the model does not need to refetch data from the database (e.g. due to scrolling or other circumstances).

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

              TheCipo76T 1 Reply Last reply
              0
              • Christian EhrlicherC Christian Ehrlicher

                It works as long as the model does not need to refetch data from the database (e.g. due to scrolling or other circumstances).

                TheCipo76T Offline
                TheCipo76T Offline
                TheCipo76
                wrote on last edited by TheCipo76
                #9

                @Christian-Ehrlicher No, i'have tried to scroll and works fine.

                This is only view of DB data.. no need to modify nothing in this dialog
                and no need to reload data

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

                  I'm giving up... would you please at least try to not to close the database and see if your problem goes away?

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

                  TheCipo76T 1 Reply Last reply
                  0
                  • Christian EhrlicherC Christian Ehrlicher

                    I'm giving up... would you please at least try to not to close the database and see if your problem goes away?

                    TheCipo76T Offline
                    TheCipo76T Offline
                    TheCipo76
                    wrote on last edited by TheCipo76
                    #11

                    @Christian-Ehrlicher Yes, i have putted "//" before close database instruction

                    //mDatabase.close();
                    

                    but warning still remain..

                    1 Reply Last reply
                    0
                    • SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by
                      #12

                      Are you calling QSqlDatabase::addDatabase("QMYSQL"); in several places in your application ?

                      Interested in AI ? www.idiap.ch
                      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                      TheCipo76T 1 Reply Last reply
                      1
                      • SGaistS SGaist

                        Are you calling QSqlDatabase::addDatabase("QMYSQL"); in several places in your application ?

                        TheCipo76T Offline
                        TheCipo76T Offline
                        TheCipo76
                        wrote on last edited by TheCipo76
                        #13

                        @SGaist Yes, in every dialog who need to connect to database..

                        but in every dialog call

                        ordforauto::~ordforauto()
                        {
                            if (aDatabase.open()) {
                                aDatabase.close();
                            }
                        QSqlDatabase::removeDatabase("QMYSQL");
                            delete ui;
                        }
                        

                        in the code or at least in the unload istructions as you see

                        1 Reply Last reply
                        0
                        • Christian EhrlicherC Offline
                          Christian EhrlicherC Offline
                          Christian Ehrlicher
                          Lifetime Qt Champion
                          wrote on last edited by
                          #14

                          http://doc.qt.io/qt-5/qsqlquery.html#details

                          Warning: You must load the SQL driver and open the connection before a QSqlQuery is created. Also, the connection must remain open while the query exists; otherwise, the behavior of QSqlQuery is undefined.

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

                          TheCipo76T 1 Reply Last reply
                          1
                          • SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #15

                            Why are you doing it like that ? There's no need to nuke and recreate the connection each time.

                            If you really want to do it like that, then you should create a connection with a different name in each of your dialog.

                            Because currently, you are manipulating the default connection from several places in a wrong manner.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            TheCipo76T 1 Reply Last reply
                            2
                            • SGaistS SGaist

                              Why are you doing it like that ? There's no need to nuke and recreate the connection each time.

                              If you really want to do it like that, then you should create a connection with a different name in each of your dialog.

                              Because currently, you are manipulating the default connection from several places in a wrong manner.

                              TheCipo76T Offline
                              TheCipo76T Offline
                              TheCipo76
                              wrote on last edited by
                              #16

                              @SGaist ok, i create the connection in the main window
                              and then only open/close database tables in every dialog?

                              is it right?

                              1 Reply Last reply
                              0
                              • Christian EhrlicherC Christian Ehrlicher

                                http://doc.qt.io/qt-5/qsqlquery.html#details

                                Warning: You must load the SQL driver and open the connection before a QSqlQuery is created. Also, the connection must remain open while the query exists; otherwise, the behavior of QSqlQuery is undefined.

                                TheCipo76T Offline
                                TheCipo76T Offline
                                TheCipo76
                                wrote on last edited by TheCipo76
                                #17

                                @Christian-Ehrlicher i will check all dialogs.. but i think that is what i've done..

                                jsulmJ 1 Reply Last reply
                                0
                                • TheCipo76T TheCipo76

                                  @Christian-Ehrlicher i will check all dialogs.. but i think that is what i've done..

                                  jsulmJ Offline
                                  jsulmJ Offline
                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on last edited by
                                  #18

                                  @TheCipo76 As shown here: http://doc.qt.io/qt-5/qsqldatabase.html
                                  Create and open db connection:

                                  QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
                                  db.setHostName("acidalia");
                                  db.setDatabaseName("customdb");
                                  db.setUserName("mojito");
                                  db.setPassword("J0a1m8");
                                  bool ok = db.open();
                                  

                                  When you need the connection just get it:

                                  QSqlDatabase db = QSqlDatabase::database();
                                  

                                  No need to open and close it all the time.

                                  https://forum.qt.io/topic/113070/qt-code-of-conduct

                                  TheCipo76T 1 Reply Last reply
                                  4
                                  • jsulmJ jsulm

                                    @TheCipo76 As shown here: http://doc.qt.io/qt-5/qsqldatabase.html
                                    Create and open db connection:

                                    QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
                                    db.setHostName("acidalia");
                                    db.setDatabaseName("customdb");
                                    db.setUserName("mojito");
                                    db.setPassword("J0a1m8");
                                    bool ok = db.open();
                                    

                                    When you need the connection just get it:

                                    QSqlDatabase db = QSqlDatabase::database();
                                    

                                    No need to open and close it all the time.

                                    TheCipo76T Offline
                                    TheCipo76T Offline
                                    TheCipo76
                                    wrote on last edited by
                                    #19

                                    @jsulm Ok, i've modify all my project and all works ok!

                                    Thanks to all for help!

                                    1 Reply Last reply
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