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  4. [solved]Total amount of column in TableView/Model

[solved]Total amount of column in TableView/Model

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  • M Offline
    M Offline
    Mr. Kibu
    wrote on last edited by
    #4

    I do not want the quantity of rows. I want the total amount of the values in column D (in my example 11). Is this possible with QAbstractItemModel::rowCount()? If yes, how can I do it?

    p3c0P 1 Reply Last reply
    0
    • M Mr. Kibu

      I do not want the quantity of rows. I want the total amount of the values in column D (in my example 11). Is this possible with QAbstractItemModel::rowCount()? If yes, how can I do it?

      p3c0P Offline
      p3c0P Offline
      p3c0
      Moderators
      wrote on last edited by
      #5

      @Mr.-Kibu Did you try the above example ? You just have to add those values.

      157

      1 Reply Last reply
      0
      • M Mr. Kibu

        Hi!

        How can I calculate the total amount of a column in a model-based tableview and show it in a label.

        I will show you my question in this picture: http://postimg.org/image/5fnhwo43x/

        Thanks a lot!

        Franz

        HarbH Offline
        HarbH Offline
        Harb
        wrote on last edited by Harb
        #6

        @Mr.-Kibu
        Hi! There is no special fucntion to calculate sum. Model is just an interface between your data and view. So if you want to calculate a sum of the column you could just implement special method in your QAbstractItemModel subclass. For example:

        int CalcColumnSum(int column)
        {
               int s=0;      
               for(int i=0;i<rowCount();++i)  
                      s+=index.(i,column,QModelIndex()).data(Qt::DisplayRole).toInt();
               return s;
        }
        

        But in fact, as I said before model is just an interface, so you don't need to interact with it to obtain data. You can obtain it directly, because you know your data structure. I don't, that why I made general example

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        • M Offline
          M Offline
          Mr. Kibu
          wrote on last edited by
          #7

          Thank you to Harb! When I use your code like this, it works:

              QSqlTableModel *testTab = new QSqlTableModel(this, ConnProjectDB::db());
          
              testTab->setTable("Test");
              testTab->select();
              ui->tableView->setModel(testTab);
          
              int s=0;
              for(int i=0;i<testTab->rowCount();++i)
                     s+=testTab->index(i,3,QModelIndex()).data(Qt::DisplayRole).toInt();
          
               QString c = QString::number(s);
               ui->label->setText(c);
          

          But if I subclass the code like this:

          h:

          private slots:
          
               int CalcColumnSum(int column, QSqlTableModel model);
          

          cpp:

              QSqlTableModel *testTab = new QSqlTableModel(this, ConnProjectDB::db());
          
              testTab->setTable("Test");
              testTab->select();
              ui->tableView->setModel(testTab);
          
              QString c = QString::number(CalcColumnSum(3,testTab));
              
              ui->label->setText(c);
          
          
          int CalcColumnSum(int column, QSqlTableModel model)
          {
                 int s=0;
                 for(int i=0;i<model.rowCount();++i)
                        s+=model.index(i,column,QModelIndex()).data(Qt::DisplayRole).toInt();
          
          }
          

          I get this error-message on building:

          "/home/franz/Dokumente/IT/QT/Projekte/BiFF/src/mainwindow.cpp:57: Fehler: no matching function for call to 'MainWindow::CalcColumnSum(int, QSqlTableModel*&)'
          QString c = QString::number(CalcColumnSum(3,testTab));
          ^"

          Is there a better way to obtain my data. Where can I obtain it directly (from the database, the tableview, )?
          In the future I want to subclass the tableview in a QSortfilterproxymodel like this:
          https://doc.qt.io/archives/4.6/itemviews-customsortfiltermodel.html

          Than I want to get the total amount from the filtered rows!

          Thank you!

          1 Reply Last reply
          0
          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #8

            Hi,

            You slot signature is the problem. You can't copy a QSqlTableModel object, it's a QObject and their copy is not allowed
            .

            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
            0
            • M Offline
              M Offline
              Mr. Kibu
              wrote on last edited by
              #9

              Okay, and what is the correct slot signature instead of "int CalcColumnSum(int column, QSqlTableModel model);"?

              1 Reply Last reply
              0
              • M Offline
                M Offline
                Mr. Kibu
                wrote on last edited by
                #10

                Is it the right way to add a pointer to the signature like this:

                CalcColumnSum(int column, QSqlTableModel *model)
                

                But now I get the error

                undefined reference to `MainWindow::CalcColumnSum(int, QSqlTableModel)*

                at the position

                QString c = QString::number(CalcColumnSum(3,testTab));
                

                Thank's for help!!

                Franz

                1 Reply Last reply
                0
                • jsulmJ Offline
                  jsulmJ Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #11

                  You have to change the definition of CalcColumnSum(int column, QSqlTableModel *model) in .cpp file as well:
                  CalcColumnSum(int column, QSqlTableModel *model)
                  {
                  ...
                  }

                  Actually, you can use a reference instead of pointer: CalcColumnSum(int column, QSqlTableModel &model)

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

                  1 Reply Last reply
                  0
                  • M Offline
                    M Offline
                    Mr. Kibu
                    wrote on last edited by
                    #12

                    Sorry, I have not said that I have already changed the definition of CalcColumnSum in cpp to "CalcColumnSum(int column, QSqlTableModel *model)".

                    But the error is still here!

                    1 Reply Last reply
                    0
                    • SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by
                      #13

                      On a side note, it's not common practice for slots to return values

                      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
                      0
                      • M Offline
                        M Offline
                        Mr. Kibu
                        wrote on last edited by Mr. Kibu
                        #14

                        The difinition of CalcColumnSum is now:

                        int CalcColumnSum(int column, QSqlTableModel *model)
                        {
                        
                            int s=0;
                               for(int i=0;i< model->rowCount();++i)
                                      s+=model->index(i,column,QModelIndex()).data(Qt::DisplayRole).toInt();
                        
                        }
                        

                        But the error is still here ....

                        1 Reply Last reply
                        0
                        • M Offline
                          M Offline
                          Mr. Kibu
                          wrote on last edited by
                          #15

                          Very stupid mistake:
                          I have forgotten to use "MainWindow::" in the definition. Here it is:

                          void MainWindow::CalcColumnSum(int col,QSqlTableModel *model)
                          {
                          ...
                          }
                          
                          1 Reply Last reply
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