use value from dynamically created widget in a slot

[Cyrebo]

Hi, I don't how to use the values from spinboxes that are dynamically created at runtime. I want to get the current value in the spinboxes when I click a push button.

Here's what I've done so far:

QFileInfo checkFile(Path_to_DB);
 
    if(checkFile.isFile())
    {
        if(db.open())
        {
            qDebug() << "Connected to database file";
        }
    }else{
        qDebug() << "Database file not found";
    }
 
    int value;
    QSqlQuery qry;
 
    if (qry.exec("SELECT name FROM customer"))
    {
        while(qry.next())
        {
            qDebug() << qry.value(0).toString();
                if(qry.isValid())
                {
                 QString cust = qry.record().value(0).toString();
 
                 //create widgets
                 QLabel *label = new QLabel(QString(cust));
                 QSpinBox *spinbox = new QSpinBox;
                 spinbox->setMaximum(3);
                 label->setGeometry(0,0,80,41);
 
                 //add to VBoxLayout
                 ui->verticalLayout->addWidget(label);
                 ui->verticalLayout->addWidget(spinbox);
                 value = spinbox->value(); // value is always going to be zero here
                 qDebug() << value;
                 }
        }
    }
    else
    {
        qDebug() << qry.lastError();
    }
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::on_pushButton_clicked()
{
    //get spinbox values
    if(!db.isOpen()){
        qDebug() << "No connection to db";
        return;
    }
  int value2;
  value2 = spinbox->value2();
  qDebug() << value2;
 
  //save values to db
   ............

QFileInfo checkFile(Path_to_DB);

    if(checkFile.isFile())
    {
        if(db.open())
        {
            qDebug() << "Connected to database file";
        }
    }else{
        qDebug() << "Database file not found";
    }

    int value;
    QSqlQuery qry;

    if (qry.exec("SELECT name FROM customer"))
    {
        while(qry.next())
        {
            qDebug() << qry.value(0).toString();
                if(qry.isValid())
                {
                 QString cust = qry.record().value(0).toString();

                 //create widgets
                 QLabel *label = new QLabel(QString(cust));
                 QSpinBox *spinbox = new QSpinBox;
                 spinbox->setMaximum(3);
                 label->setGeometry(0,0,80,41);

                 //add to VBoxLayout
                 ui->verticalLayout->addWidget(label);
                 ui->verticalLayout->addWidget(spinbox);
                 value = spinbox->value(); // value is always going to be zero here
                 qDebug() << value;
                 }
        }
    }
    else
    {
        qDebug() << qry.lastError();
    }
}

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

void MainWindow::on_pushButton_clicked()
{
    //get spinbox values
    if(!db.isOpen()){
        qDebug() << "No connection to db";
        return;
    }
  int value2;
  value2 = spinbox->value2();
  qDebug() << value2;

  //save values to db
   ............

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Thanks in advance!

--

[Lesiok]

Save spinbox pointers to the list defined in MainWindow class (QList<QSpinBox*>).

[Cyrebo]

Save spinbox pointers to the list defined in MainWindow class (QList<QSpinBox*>).

Thanks for the quick reply. When I do that I get the following error:

/mainwindow.cpp:68: error: 'spinbox' cannot appear in a constant-expression

This is what I did:

QString cust = qry.record().value(0).toString();
                 QLabel *label = new QLabel(QString(cust));
                 QSpinBox *spinbox = new QSpinBox(this);
                 QList<*spinbox>;

QString cust = qry.record().value(0).toString();
                 QLabel *label = new QLabel(QString(cust));
                 QSpinBox *spinbox = new QSpinBox(this);
                 QList<*spinbox>;

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[wysota]

It should be QList<QSpinBox*>, however defining the list as a local variable will not do you any good. You need to be able to access that variable from scopes other than this function.

[Cyrebo]

It should be QList<QSpinBox*>, however defining the list as a local variable will not do you any good. You need to be able to access that variable from scopes other than this function.

How should it be declared to be accessed from various scopes?

[wysota]

How should it be declared to be accessed from various scopes?

This is really no place to teach you C++. The issue you have is completely unrelated to Qt. You can make the variable a class member or a global one but I'm afraid that without proper C++ skills you'll get stuck again. I suggest you read a good book on C++ or do a couple of C++ tutorials.

[Cyrebo]

I'm really new to c++ actually, so im not use to classes like you have in java also. I'm pretty good with just ordinary c though and in C to declare something to be accessed from anywhere you declare it at the top of your program. Then it may be accessed by "functions" rather than classes. It's good that it's not qt related so I just need to find out how to declare stuff globally in c++.

But can you tell me how to use functions in qt? I wanted to make the whole creating layout part a function.

[wysota]

Qt is exactly the same as regular C++. Once you learn C++, you'll know how to use functions in Qt as well. Using functions in C++ is exactly the same as in C, by the way.

[Cyrebo]

Well actually, I can use functions in the main.cpp, I just need to know how to use them in mainwindow class please.

[wysota]

I already said, functions in C and C++ work the same way, with respect to scopes (such as classes).

[Cyrebo]

Yes I understand, I can use it in c++ in the main.cpp, what I want to know is how to use in mainwindow.cpp. I put in the exact same code and it says "expected a declaration" when its supposed to be a function...

[giblit]

Well actually, I can use functions in the main.cpp, I just need to know how to use them in mainwindow class please.

if you create a mew qt gui file it should do that for you automatically other wise you can do it manually->

use a header like this:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
 
 
class MainWindow: public QMainWindow
{
Q_OBJECT
 
public:
   MainWindow();
~MainWindow();
 
 
private slots:
void functionSlot();
 
private:
    void function();
 
    //QWidgetType *QWidgetName..... 
//ex:
 QPushButton *pushButton;
 
};
 
#endif

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>


class MainWindow: public QMainWindow
{
Q_OBJECT

public:
   MainWindow();
~MainWindow();


private slots:
void functionSlot();

private:
    void function();

    //QWidgetType *QWidgetName..... 
//ex:
 QPushButton *pushButton;

};

#endif

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then on the mainWindow cpp file

#include <QtGui>
#include "mainwindow.h"
 
 
MainWindow::MainWindow(){
pushButton = newQPushButton;
function();
}
void MainWindow::function(){
pusButton->setText("Button");
//do something
}

#include <QtGui>
#include "mainwindow.h"


MainWindow::MainWindow(){
pushButton = newQPushButton;
function();
}
void MainWindow::function(){
pusButton->setText("Button");
//do something
}

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and on the main.cpp file

#include <QtGui/QApplication>
#inlucde "mainwindow.h"
 
int main(int argc, char *argv[]){
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}

#include <QtGui/QApplication>
#inlucde "mainwindow.h"

int main(int argc, char *argv[]){
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}

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[Cyrebo]

Thanks man, I've been looking for something like that all day but I still get this error on runtime..

-build-desktop-Qt_4_8_3_in_PATH__System__Release/moc_mainwindow.cpp:-1: error: undefined reference to `MainWindow::dbinfoSlot()'