Send parameters with dynamically generated QComboBox-CodePudding

I want to insert a QComboBox inside a QTableWidget. When I change the Index of the CB I'll call a methode to change the status in the sqlite table. But for this, I need do pass two parameters to the methode. The ID(First element of the row), and the current index of the CB.

I generate the QTableWidget like that:

...
for(int i = 0; i < dbModel->rowCount();i  ){
    row = dbModel->record(i);
    ui->tW_Services->setItem(i,0,new QTableWidgetItem(row.field(0).value().toString()));
    ui->tW_Services->setItem(i,1,new QTableWidgetItem(row.field(1).value().toString()));
    ui->tW_Services->setItem(i,2,new QTableWidgetItem(row.field(2).value().toString()));
    ui->tW_Services->setItem(i,3,new QTableWidgetItem(row.field(3).value().toString()));
    ui->tW_Services->setItem(i,4,new QTableWidgetItem(row.field(4).value().toString()   "€"));
    ui->tW_Services->setItem(i,5,new QTableWidgetItem(row.field(5).value().toString()   "€"));
    //ui->tW_Services->setItem(i,6,new QTableWidgetItem(row.field(6).value().toString()));

    QComboBox* combo = new QComboBox();
    combo->addItem("open");
    combo->addItem("paid");
    if(row.field(6).value().toString() != "paid") combo->setCurrentIndex(0);
    else combo->setCurrentIndex(1);
    connect(combo, SIGNAL(currentIndexChanged(int)), this, SLOT(onComboChanged(int)));
    ui->tW_Services->setCellWidget(i,6,combo);
}
...

and the slot looks like that:

    void MainWindow::onComboChanged(int ID)
{
    qDebug() << "ID:" << QString::number(ID);
}

But when I try to create the method with 2 args:

    void MainWindow::onComboChanged(int ID,int index)
{
    qDebug() << "ID:" << QString::number(ID);
}

and attach a second parameter and calling the slot like:

connect(combo, SIGNAL(currentIndexChanged(int)), this, SLOT(onComboChanged(row.field(0).value().toInt(),int)));

I get:

qt.core.qobject.connect: QObject::connect: No such slot MainWindow::onComboChanged(row.field(0).value().toInt(),int)

A minimal reproducible example: There's just a single pushbutton and a qtablewidget

mainwindow.h:

    #ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_pushButton_clicked();

    void onComboChanged(int ID, int index);

    void onComboChanged2(int index);

private:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QComboBox>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_pushButton_clicked()
{
    ui->tableWidget->setColumnCount(4);
    ui->tableWidget->setRowCount(3);

    for(int i = 0; i < 3;i  ){
        ui->tableWidget->setItem(i,0,new QTableWidgetItem(QString::number(i)));
        ui->tableWidget->setItem(i,1,new QTableWidgetItem("Test"));
        ui->tableWidget->setItem(i,2,new QTableWidgetItem("Test 2"));

        QComboBox* combo = new QComboBox();
        combo->addItem("open");
        combo->addItem("paid");
        combo->setCurrentIndex(0);
        int j = i 1;

        //NOT WORKING
        //connect(combo, SIGNAL(currentIndexChanged(int)),this,
        //        [=](int index) {this->onComboChanged(j, index);});

        //WORKING
        //connect(combo, SIGNAL(currentIndexChanged(int)),SLOT(onComboChanged2(int)));
        ui->tableWidget->setCellWidget(i,3,combo);
    }
}

void MainWindow::onComboChanged(int ID, int index)
{
    qDebug() << "ID: " << ID << "index: "<< index;
}

void MainWindow::onComboChanged2(int index)
{
    qDebug() << "ID: " << index;
}

CodePudding user response：

Since currentIndexChanged only has one parameter, your slot cannot capture more than that. But, since the row ID does not change on emission, you can wrap onComboChanged into a lambda as shown here, which captures the row by copy:

connect(combo, &QComboBox::currentIndexChanged,
        this, [=](int index) {this->onComboChanged(i, index);});

Since your code is not a minimal reproducible example, I could not test this. Let me know, if it doesn't work.