Qtableview calculation

[n-2204]

As i am new i dont understand how to implement in my model.
so to implement i need to understand how to do/ create functions.

i need to implement some formula not just add in columns so automatic calculation will happen when user enter data in columns

[Christian Ehrlicher]

When you don't have an own model yet you should start with https://doc.qt.io/qt-5/model-view-programming.html and it's examples.

[n-2204]

@Christian-Ehrlicher i have models
model = new QStandardItemModel(7, 13, this);//row*col
model2 = new QStandardItemModel(7, 20, this);
model3 = new QStandardItemModel(7, 10, this);
but the calculaion part i dont understand how to implement

[Christian Ehrlicher]

@n-2204 said in Qtableview calculation:

but the calculaion part i dont understand how to implement

as I already said you have to implement your own model, read the docs!

[n-2204]

@Christian-Ehrlicher can i get any related examples from any site ?
one approach is data() change using QAbstractTableModel()
and i have 3 model so how to do in that case?

QVariant calculationm::data( const QModelIndex &index, int role ) const
{
switch( role )
{
case Qt::DisplayRole:
}

[Christian Ehrlicher]

@n-2204 said in Qtableview calculation:

can i get any related examples from any site ?

There are enough on this side... to lazy to search?
No more comments from me here.

[n-2204]

@Christian-Ehrlicher i already search but not found thats why asking .
if i able to found then no need to ask here.
and i have written the approach also how to do
Thanks for you comments

[VRonin]

You can use KExtraColumnsProxyModel: https://api.kde.org/frameworks/kitemmodels/html/classKExtraColumnsProxyModel.html

#include <QApplication>
#include <QStandardItemModel>
#include <QTableView>
#include <KExtraColumnsProxyModel>

class ExampleCalcProxy : public KExtraColumnsProxyModel{
    Q_DISABLE_COPY(ExampleCalcProxy)
public:
    explicit ExampleCalcProxy(QObject* parent = nullptr)
        : KExtraColumnsProxyModel(parent)
    {
        // the first extra column will sum the column 0 and 1
        appendColumn(tr("Sum"));
        // the second extra column will multiply the column 0 and 1
        appendColumn(tr("Product"));
    }
    QVariant extraColumnData ( const QModelIndex &  parent, int  row, int  extraColumn, int  role = Qt::DisplayRole) const override{
        if (role != Qt::DisplayRole && role != Qt::EditRole)
            return QVariant();
        const double column0data = index(row,0,parent).data(role).toDouble();
        const double column1data = index(row,1,parent).data(role).toDouble();
        switch (extraColumn) {
        case 0:
            return column0data+column1data;
        case 1:
            return column0data*column1data;
        default:
            return QVariant();
        }
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    // create a model with 2 columns
    //and 5 rows and fill it with random numbers
    QStandardItemModel model;
    model.insertColumns(0,2);
    model.insertRows(0,5);
    for(int i=0;i<5;++i){
        for(int j=0;j<2;++j){
            model.setData(model.index(i,j),rand()%100);
        }
    }
    // instantiate the proxy and set the source model
    ExampleCalcProxy proxy;
    proxy.setSourceModel(&model);
    // usa a table view to display the result
    QTableView view;
    view.setModel(&proxy);
    view.show();
    return a.exec();
}

[n-2204]

i need to implement the table formula for column i added at column
i have created tableview using model
there are 3 qtableview
model = new QStandardItemModel(7, 13, this);//row*col
model2 = new QStandardItemModel(7, 20, this);
model3 = new QStandardItemModel(7, 10, this);
model->setHeaderData(0, Qt::Horizontal, tr(" no# "));
model->setHeaderData(1, Qt::Horizontal, tr(" N "))
now how can i implement calculation in a separate cpp file
how can i do this ? i am new to Qt and c++ please suggest
Thanks in advance

[JonB]

@n-2204 said in Qtableview calculation:

there are 3 qtableview

No, there is one QTableView shown. There seem to be 3 models. Why do you have 3 separate models? What you seem to have is one model, with 2 columns of input data (P & N) and 3 columns of calculated data. Unless you have some requirement I don't understand, that is what you want. That is also the principle employed in @VRonin's example.

[n-2204]

There seem to be 3 models.
Why do you have 3 separate models? What you seem to have is one model, with 2 columns of input data (P & N) and 3 columns of calculated data

colored column will be user input and other column have some formula when use enter data so other column should update accordingly
if for one table i implement then i understand how to do so i just shared one table picture
so i dont understand the implementation of formula
. Unless you have some requirement I don't understand, that is what you want.