Qtableview calculation

n-2204

Anyone can share the qtableview code or any example
where any calculation is implemented on columns.
like if user enter in column 1 and 2 so in column 3 result will display. and like that

Christian Ehrlicher

Override data() in your model and return the sum of col1 and col2 for col3 for Qt::DisplayRole

n-2204

@Christian-Ehrlicher actually this i am asking for example purpose i have to implement different formula in columns not only one

Christian Ehrlicher

@n-2204 said in Qtableview calculation:

this i am asking for example purpose

I don't know what example you want here. When you've your own model you also have to implement your own data() function where you can return whatever you want for every cell.

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.