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Update QSqlTableModel after QSqlQuery executing

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  • W Offline
    W Offline
    Wuzi
    wrote on last edited by Wuzi
    #1

    Hi,

    I'm trying to add a column from an sql database with Qsql. With QSqlTableModel this is not possible and therefore I created a query to do that:
    QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
    QSqlQuery query("", *m_db);
    bool status = query.exec(query_);
    This works fine and when opening the database in a db browser, the column was added

    The problem now is, that the view is not updated. I already tried
    QSqlTableModel::select() to repopulate the model, but the removed columns still occur.

    How do I update the View/ model after querying sql commands manually?

    JonBJ 1 Reply Last reply
    0
    • JonBJ JonB

      @Wuzi said in Update QSqlTableModel after QSqlQuery executing:

          m_model->selectStatement(); // I don't see the new column here
          m_model->setQuery(query);
          m_model->selectStatement(); // The selectStatement is empty
          //m_model->setTable(m_model->tableName());
          m_model->selectStatement(); // query is fine and the new column is shown in the table view
      

      I simply do not believe the "query is fine" in the third selectStatement() you show here. I can believe it would be fine if you uncommented the setTable() statement, but that is not what you show. Nonetheless is that what you mean??

      The idea is now to update the query of the model every time I'm executing a new query?

      Not for every query, but yes for the very unusual case where you add/remove/alter columns. You have to tell QSqlTableModel to re-read the table definition, and setTable() should do that.

      Finally, I cannot imagine why you persist in m_model->setQuery(query);. Your query is an ALTER TABLE statement. that is totally unsuitable as the statement for reading data from a table, which should be a SELECT statement. You don't need to set that (setTable() will sort it out), but don't set it to some completely unrelated statement.

      W Offline
      W Offline
      Wuzi
      wrote on last edited by Wuzi
      #22

      @JonB said in Update QSqlTableModel after QSqlQuery executing:

      I simply do not believe the "query is fine" in the third selectStatement() you show here. I can believe it would be fine if you uncommented the setTable() statement, but that is not what you show.

      @JonB said in Update QSqlTableModel after QSqlQuery executing:

      Finally, I cannot imagine why you persist in m_model->setQuery(query);. Your query is an ALTER TABLE statement. that is totally unsuitable

      You are right. SELECT is the correct one

      Sorry. I played around to check and forgott to enable it again. I edited the code above

      Yes I think setTable and does the job. I thought there is a different way doing it.

      Thank you all for helping!

      1 Reply Last reply
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      • Christian EhrlicherC Offline
        Christian EhrlicherC Offline
        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on last edited by
        #2

        You have to set a new query afaics.

        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
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        • W Offline
          W Offline
          Wuzi
          wrote on last edited by
          #3

          What do you mean?

          W 1 Reply Last reply
          0
          • Christian EhrlicherC Offline
            Christian EhrlicherC Offline
            Christian Ehrlicher
            Lifetime Qt Champion
            wrote on last edited by
            #4

            @Wuzi said in Update QSqlTableModel after QSqlQuery executing:

            What do you mean?

            call QSqlTableModel::setQuery() again

            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
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            • W Wuzi

              Hi,

              I'm trying to add a column from an sql database with Qsql. With QSqlTableModel this is not possible and therefore I created a query to do that:
              QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
              QSqlQuery query("", *m_db);
              bool status = query.exec(query_);
              This works fine and when opening the database in a db browser, the column was added

              The problem now is, that the view is not updated. I already tried
              QSqlTableModel::select() to repopulate the model, but the removed columns still occur.

              How do I update the View/ model after querying sql commands manually?

              JonBJ Offline
              JonBJ Offline
              JonB
              wrote on last edited by
              #5

              @Wuzi
              You could also try https://doc.qt.io/qt-5/qabstractitemmodel.html#beginResetModel, you'd have to verify whether that works.

              1 Reply Last reply
              0
              • W Wuzi

                What do you mean?

                W Offline
                W Offline
                Wuzi
                wrote on last edited by Wuzi
                #6

                @Christian-Ehrlicher
                should I call setQuery every time I'm executing a query or it is enough to call it at the end? After calling, nothing is shown anymore

                W 1 Reply Last reply
                0
                • W Wuzi

                  @Christian-Ehrlicher
                  should I call setQuery every time I'm executing a query or it is enough to call it at the end? After calling, nothing is shown anymore

                  W Offline
                  W Offline
                  Wuzi
                  wrote on last edited by
                  #7

                  @Christian-Ehrlicher
                  I tried to call beginResetModel() and endResetModel() but it did not change anything. But this methods are for signaling the views, but I think the model is not updated

                  Christian EhrlicherC 1 Reply Last reply
                  1
                  • W Wuzi

                    @Christian-Ehrlicher
                    I tried to call beginResetModel() and endResetModel() but it did not change anything. But this methods are for signaling the views, but I think the model is not updated

                    Christian EhrlicherC Offline
                    Christian EhrlicherC Offline
                    Christian Ehrlicher
                    Lifetime Qt Champion
                    wrote on last edited by
                    #8

                    @Wuzi I never said anything about begin/endResetModel() - you should not call it. When you call setQuery() with the original query the view should not be empty - please show some code.

                    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
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                    • JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on last edited by
                      #9

                      It was I who suggested trying beginResetModel(), I did say you would need to verify. Evidently that is not correct, it was a suggestion which was wrong.

                      W 1 Reply Last reply
                      0
                      • JonBJ JonB

                        It was I who suggested trying beginResetModel(), I did say you would need to verify. Evidently that is not correct, it was a suggestion which was wrong.

                        W Offline
                        W Offline
                        Wuzi
                        wrote on last edited by
                        #10

                        @JonB
                        Sorry for the wrong quote. I just wrote it down to track that this was tested :)

                        1 Reply Last reply
                        0
                        • W Offline
                          W Offline
                          Wuzi
                          wrote on last edited by
                          #11

                          @Christian-Ehrlicher
                          Here the code. I can also publish the complete code if needed, but I think it is too much. You can find it here

                          class SqlTableModel : public QSqlTableModel
                          {
                              Q_OBJECT
                          public:
                              SqlTableModel(QObject *parent = nullptr, QSqlDatabase db = QSqlDatabase());
                              void setQuery(QSqlQuery& query);
                              void reset();
                          };
                          
                          void SqlTableModel::setQuery(QSqlQuery &query) {
                              QSqlTableModel::setQuery(query);
                          }
                          
                                  QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
                                  QSqlQuery query("", *m_db);
                                  bool status = query.exec(query_);
                          
                                  if (!status) {
                                      QString err = query.lastError().text();
                                      //emit errorOccured(err);
                                  }
                                  m_model->setQuery(query);
                          
                          JonBJ SGaistS 3 Replies Last reply
                          0
                          • W Wuzi

                            @Christian-Ehrlicher
                            Here the code. I can also publish the complete code if needed, but I think it is too much. You can find it here

                            class SqlTableModel : public QSqlTableModel
                            {
                                Q_OBJECT
                            public:
                                SqlTableModel(QObject *parent = nullptr, QSqlDatabase db = QSqlDatabase());
                                void setQuery(QSqlQuery& query);
                                void reset();
                            };
                            
                            void SqlTableModel::setQuery(QSqlQuery &query) {
                                QSqlTableModel::setQuery(query);
                            }
                            
                                    QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
                                    QSqlQuery query("", *m_db);
                                    bool status = query.exec(query_);
                            
                                    if (!status) {
                                        QString err = query.lastError().text();
                                        //emit errorOccured(err);
                                    }
                                    m_model->setQuery(query);
                            
                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by JonB
                            #12
                            This post is deleted!
                            1 Reply Last reply
                            0
                            • W Wuzi

                              @Christian-Ehrlicher
                              Here the code. I can also publish the complete code if needed, but I think it is too much. You can find it here

                              class SqlTableModel : public QSqlTableModel
                              {
                                  Q_OBJECT
                              public:
                                  SqlTableModel(QObject *parent = nullptr, QSqlDatabase db = QSqlDatabase());
                                  void setQuery(QSqlQuery& query);
                                  void reset();
                              };
                              
                              void SqlTableModel::setQuery(QSqlQuery &query) {
                                  QSqlTableModel::setQuery(query);
                              }
                              
                                      QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
                                      QSqlQuery query("", *m_db);
                                      bool status = query.exec(query_);
                              
                                      if (!status) {
                                          QString err = query.lastError().text();
                                          //emit errorOccured(err);
                                      }
                                      m_model->setQuery(query);
                              
                              JonBJ Offline
                              JonBJ Offline
                              JonB
                              wrote on last edited by JonB
                              #13

                              @Wuzi

                              After calling, nothing is shown anymore

                                      QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
                                      QSqlQuery query("", *m_db);
                                      bool status = query.exec(query_);
                                      m_model->setQuery(query);
                              

                              At the end of this, I wonder what the model gets as its query for populating from the table? Are you expecting it to discover that the table's columns have changed?

                              1 Reply Last reply
                              0
                              • W Wuzi

                                @Christian-Ehrlicher
                                Here the code. I can also publish the complete code if needed, but I think it is too much. You can find it here

                                class SqlTableModel : public QSqlTableModel
                                {
                                    Q_OBJECT
                                public:
                                    SqlTableModel(QObject *parent = nullptr, QSqlDatabase db = QSqlDatabase());
                                    void setQuery(QSqlQuery& query);
                                    void reset();
                                };
                                
                                void SqlTableModel::setQuery(QSqlQuery &query) {
                                    QSqlTableModel::setQuery(query);
                                }
                                
                                        QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
                                        QSqlQuery query("", *m_db);
                                        bool status = query.exec(query_);
                                
                                        if (!status) {
                                            QString err = query.lastError().text();
                                            //emit errorOccured(err);
                                        }
                                        m_model->setQuery(query);
                                
                                SGaistS Offline
                                SGaistS Offline
                                SGaist
                                Lifetime Qt Champion
                                wrote on last edited by SGaist
                                #14

                                Hi,

                                @Wuzi said in Update QSqlTableModel after QSqlQuery executing:

                                QSqlQuery query("", *m_db);

                                Two things here looks wrong:

                                • why do you have a pointer to QSqlDatabase object ?
                                • why do you have a QSqlDatabase member variable ? There's a warning about that in the QSqlDatabase documentation.

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

                                1 Reply Last reply
                                1
                                • W Offline
                                  W Offline
                                  Wuzi
                                  wrote on last edited by
                                  #15

                                  @JonB said in Update QSqlTableModel after QSqlQuery executing:

                                  At the end of this, I wonder what the model gets as its query for populating from the table? Are you expecting it to discover that the table's columns have changed?

                                  Yes I expect that the model resets and adds the column. So thats wrong?

                                  @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                  why do you have a pointer to QSqlDatabase object ?
                                  Because I stored a pointer to the database, otherwise I have multiple objects on the same database?

                                  @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                  why do you have a QSqlDatabase member variable ? There's a warning about that in the QSqlDatabase documentation.
                                  The link is broken.

                                  What is the best way to update the model and the view?

                                  JonBJ SGaistS 2 Replies Last reply
                                  0
                                  • W Wuzi

                                    @JonB said in Update QSqlTableModel after QSqlQuery executing:

                                    At the end of this, I wonder what the model gets as its query for populating from the table? Are you expecting it to discover that the table's columns have changed?

                                    Yes I expect that the model resets and adds the column. So thats wrong?

                                    @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                    why do you have a pointer to QSqlDatabase object ?
                                    Because I stored a pointer to the database, otherwise I have multiple objects on the same database?

                                    @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                    why do you have a QSqlDatabase member variable ? There's a warning about that in the QSqlDatabase documentation.
                                    The link is broken.

                                    What is the best way to update the model and the view?

                                    JonBJ Offline
                                    JonBJ Offline
                                    JonB
                                    wrote on last edited by
                                    #16

                                    @Wuzi said in Update QSqlTableModel after QSqlQuery executing:

                                    Yes I expect that the model resets and adds the column. So thats wrong?

                                    Let's start with clarity of what you typed:

                                    I'm trying to remove a column from an sql database with Qsql.

                                    Here the code
                                    QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3")

                                    So you're trying to remove a column by adding a column? It would really help if there was some consistency between the question you ask and the code you show....

                                    Earlier you said:

                                    The problem now is, that the view is not updated. I already tried

                                    QSqlTableModel::select() to repopulate the model, but the removed columns still occur.

                                    I suspect/wonder that the model does not get updated after column add/remove, rather than the view? I don't know what you think will cause the model to see the changed columns. It should be easy for you discover whether the issue lies at model side or view. You could check the query from QSqlTableModel::query(), or you could sub-class QSqlTableModel (IMHO always advisable) so that you can check QSqlTableModel::selectStatement().

                                    1 Reply Last reply
                                    1
                                    • W Offline
                                      W Offline
                                      Wuzi
                                      wrote on last edited by Wuzi
                                      #17

                                      @JonB said in Update QSqlTableModel after QSqlQuery executing:

                                      So you're trying to remove a column by adding a column? It would really help if there was some consistency between the question you ask and the code you show....

                                      Sorry for that. The problem is the same for adding a column, but in sqlite removing column does not exist and therefore multiple queries must be executed. To make it easier, I took Add instead Remove.
                                      I updated the question to get consistence

                                      JonBJ 1 Reply Last reply
                                      0
                                      • W Wuzi

                                        @JonB said in Update QSqlTableModel after QSqlQuery executing:

                                        So you're trying to remove a column by adding a column? It would really help if there was some consistency between the question you ask and the code you show....

                                        Sorry for that. The problem is the same for adding a column, but in sqlite removing column does not exist and therefore multiple queries must be executed. To make it easier, I took Add instead Remove.
                                        I updated the question to get consistence

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

                                        @Wuzi
                                        That's OK, I'm often irritable with the way people write questions ;-) Check out the later stuff in my post, I think you need to narrow down for sure what is going on with your table model query after you alter columns before you know whether you are looking at a model or view issue.

                                        1 Reply Last reply
                                        0
                                        • W Wuzi

                                          @JonB said in Update QSqlTableModel after QSqlQuery executing:

                                          At the end of this, I wonder what the model gets as its query for populating from the table? Are you expecting it to discover that the table's columns have changed?

                                          Yes I expect that the model resets and adds the column. So thats wrong?

                                          @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                          why do you have a pointer to QSqlDatabase object ?
                                          Because I stored a pointer to the database, otherwise I have multiple objects on the same database?

                                          @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                          why do you have a QSqlDatabase member variable ? There's a warning about that in the QSqlDatabase documentation.
                                          The link is broken.

                                          What is the best way to update the model and the view?

                                          SGaistS Offline
                                          SGaistS Offline
                                          SGaist
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #19

                                          @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                          why do you have a pointer to QSqlDatabase object ?
                                          Because I stored a pointer to the database, otherwise I have multiple objects on the same database?

                                          QSqlDatabase manages the connections. When needed ask it for the connection you want to use.

                                          @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                          why do you have a QSqlDatabase member variable ? There's a warning about that in the QSqlDatabase documentation.
                                          The link is broken.

                                          Link fixed.

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

                                          W 1 Reply Last reply
                                          1
                                          • SGaistS SGaist

                                            @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                            why do you have a pointer to QSqlDatabase object ?
                                            Because I stored a pointer to the database, otherwise I have multiple objects on the same database?

                                            QSqlDatabase manages the connections. When needed ask it for the connection you want to use.

                                            @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                            why do you have a QSqlDatabase member variable ? There's a warning about that in the QSqlDatabase documentation.
                                            The link is broken.

                                            Link fixed.

                                            W Offline
                                            W Offline
                                            Wuzi
                                            wrote on last edited by Wuzi
                                            #20

                                            @SGaist said in Update QSqlTableModel after QSqlQuery executing:

                                            QSqlDatabase manages the connections. When needed ask it for the connection you want to use.
                                            Ah ok thanks.

                                            @JonB said in Update QSqlTableModel after QSqlQuery executing:

                                            I suspect/wonder that the model does not get updated after column add/remove, rather than the view? I don't know what you think will cause the model to see the changed columns. It should be easy for you discover whether the issue lies at model side or view. You could check the query from QSqlTableModel::query(), or you could sub-class QSqlTableModel (IMHO always advisable) so that you can check QSqlTableModel::selectStatement().

                                            Ok I don't see there my new column.

                                                void redo() override {
                                                    QString query_ = QString("ALTER TABLE %1 ADD COLUMN %2 %3").arg(m_table).arg(m_name).arg(m_type);
                                                    QSqlQuery query("", *m_db);
                                                    bool status = query.exec(query_);
                                            
                                                    if (!status) {
                                                        QString err = query.lastError().text();
                                                        //emit errorOccured(err);
                                                    }
                                                    query.finish();
                                                    m_model->selectStatement(); // I don't see the new column here
                                                    m_model->setQuery(query);
                                                    m_model->selectStatement(); // The selectStatement is empty
                                                    m_model->setTable(m_model->tableName());
                                                    m_model->selectStatement(); // query is fine and the new column is shown in the table view
                                                }
                                            

                                            So the question is, why in the second selectStatement() call the query is empty?
                                            The idea is now to update the query of the model every time I'm executing a new query?

                                            JonBJ 1 Reply Last reply
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