QComboBox Problem

Hello!
How to choose what is the value of QComboBox which I want to be displayed in the loading of the interface.
I read the documentation and I found this method "setItemText (int index, QString text)" as I used to index 0 for the value to be displayed first but it result nothing.
What should I do? Thank you in advance
NB: the values ​​of my QComboBox are loaded from a database.

Do you want to set another current item?
Use

Code:

---

void setCurrentIndex(int index)

---

.

Thank you for your response.
The problem is that my comboBox is bound by one slot to another comboBox_Global ie when I change the value of my ComboxBox_Global, the value of comboBox is not changed
As if there is no synchronization between them.
This is the code:

Code:

---

this->model = new QSqlQueryModel();
           model->setQuery("SELECT  Nom FROM Projet.dbo.Produit");
           ui->comboBox->setModel(model);
this->model2 = new QSqlQueryModel();
                  model2->setQuery("SELECT DISTINCT N_Four FROM Projet.dbo.Produit");
                  ui->comboBox_2->setModel(model2);
 
 
                  QSqlQuery query5;
                  query5.prepare("SELECT  N_Four FROM Projet.dbo.Produit WHERE Nom=:nom");
                  query5.bindValue(":nom", ui->comboBox->currentText());
                  if (query5.exec() && query5.next()) {
                      ui->comboBox_2->setItemText(0,query5.value(0).toString());
 
                  }
void fiche_article::on_comboBox_currentIndexChanged(const QString &arg1)
{
 
 
    QSqlQuery query5;
    query5.prepare("SELECT  N_Four FROM Projet.dbo.Produit WHERE Nom=:nom");
    query5.bindValue(":nom", ui->comboBox->currentText());
    if (query5.exec() && query5.next()) {
        ui->comboBox_2->setItemText(0,query5.value(0).toString());
 
    }

---

my_widget.h:

Code:

---

#include <QtGui>
 
class MyWidget : public QWidget
{
    Q_OBJECT
    public:
        MyWidget(QWidget* parent = 0)
        {
            QHBoxLayout* layout = new QHBoxLayout(this);
            combo1 = new QComboBox(this);
            combo2 = new QComboBox(this);
 
            layout->addWidget(combo1);
            layout->addWidget(combo2);
 
            combo1->addItem("combo_item1");
            combo1->addItem("combo_item2");
            combo2->addItem("combo_item3");
            combo2->addItem("combo_item4");
 
            connect(combo1, SIGNAL(currentIndexChanged(const QString&)),
            this,   SLOT(_onCombo1_currentIndexChanged(const QString&)));
        }
 
private slots:
        void _onCombo1_currentIndexChanged(const QString &arg1)
        {
            QString val("trololo");
            //take value from database here...
 
            combo2->setItemText(0, val);
        }
 
    private:
        QComboBox* combo1;
        QComboBox* combo2;
};

---

main.cpp:

Code:

---

#include "my_widget.h"
 
int main(int argc, char** argv)
{
    QApplication app(argc, argv);
 
    MyWidget w;
    w.show();
 
    return app.exec();
}

---

This example works fine for me.
It's will be much harder to find a problem if your actual problem is in your database code.
But synchronization between two combo boxes is not a problem.

If I've got you wrong, can you tell me:
what is a value that query5.value(0).toString() returns?
was ui variable constructed?
was setupUi method called?

Hello, thank you for answering me again.

I didn't understand your code perfectly. In fact, i can't see the utility of creating everything on header( i use the header only for declaration)
I will answer your questions :
query5.value(0).toString returns the num_Four from my base
ui is the mainwindow widget
and i will post the hole code here :

fiche_article.cpp :

Code:

---

#include "fiche_article.h"
#include "ui_fiche_article.h"
#include <QtDebug>
 
fiche_article::fiche_article(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::fiche_article)
{
    ui->setupUi(this);
    this->model = new QSqlQueryModel();
           model->setQuery("SELECT  Nom FROM Projet.dbo.Produit");
           ui->comboBox->setModel(model);
 
 
           QSqlQuery query;
           query.prepare("SELECT  Matricule FROM Projet.dbo.Produit WHERE Nom=:nom");
           query.bindValue(":nom", ui->comboBox->currentText());
           if (query.exec() && query.next()) {
               ui->lineEdit_3->setText(query.value(0).toString());
           }
         //  QObject::connect(ui->comboBox, SIGNAL(currentIndexChanged(int)),ui->lineEdit_3, SLOT(setText(ui->comboBox->currentText())));
 
           QSqlQuery query2;
           query2.prepare("SELECT  Nom FROM Projet.dbo.Produit WHERE Nom=:nom");
           query2.bindValue(":nom", ui->comboBox->currentText());
           if (query2.exec() && query2.next()) {
               ui->lineEdit->setText(query2.value(0).toString());
           }
 
 
           QSqlQuery query3;
           query3.prepare("SELECT  Type FROM Projet.dbo.Produit WHERE Nom=:nom");
           query3.bindValue(":nom", ui->comboBox->currentText());
           if (query3.exec() && query3.next()) {
               ui->lineEdit_2->setText(query3.value(0).toString());
 
           }
 
           QSqlQuery query4;
           query4.prepare("SELECT  Quantité FROM Projet.dbo.Produit WHERE Nom=:nom");
           query4.bindValue(":nom", ui->comboBox->currentText());
           if (query4.exec() && query4.next()) {
               ui->spinBox->setValue(query4.value(0).toInt());
 
 
           }
           this->model2 = new QSqlQueryModel();
                  model2->setQuery("SELECT DISTINCT N_Four FROM Projet.dbo.Produit");
                  ui->comboBox_2->setModel(model2);
 
 
                  QSqlQuery query5;
                  query5.prepare("SELECT  N_Four FROM Projet.dbo.Produit WHERE Nom=:nom");
                  query5.bindValue(":nom", ui->comboBox->currentText());
                  if (query5.exec() && query5.next()) {
                      ui->comboBox_2->setItemText(0,query5.value(0).toString());
 
                  }
 
 
}
 
fiche_article::~fiche_article()
{
    delete ui;
}
 
void fiche_article::on_comboBox_currentIndexChanged(const QString &arg1)
{
 
    QSqlQuery query;
    query.prepare("SELECT  Matricule FROM Projet.dbo.Produit WHERE Nom=:nom");
    query.bindValue(":nom", ui->comboBox->currentText());
    if (query.exec() && query.next()) {
        ui->lineEdit_3->setText(query.value(0).toString());
    }
    QSqlQuery query3;
    query3.prepare("SELECT  Type FROM Projet.dbo.Produit WHERE Nom=:nom");
    query3.bindValue(":nom", ui->comboBox->currentText());
    if (query3.exec() && query3.next()) {
        ui->lineEdit_2->setText(query3.value(0).toString());
    }
 
    QSqlQuery query4;
    query4.prepare("SELECT  Quantité FROM Projet.dbo.Produit WHERE Nom=:nom");
    query4.bindValue(":nom", ui->comboBox->currentText());
    if (query4.exec() && query4.next()) {
        ui->spinBox->setValue(query4.value(0).toInt());
 
    }
 
 
}

---

fiche_article.h :

Code:

---

#ifndef FICHE_ARTICLE_H
#define FICHE_ARTICLE_H
 
#include <QDialog>
#include <QtGui>
#include <QtSql>
#include <QtCore>
 
namespace Ui {
    class fiche_article;
}
 
class fiche_article : public QDialog
{
    Q_OBJECT
 
public:
    explicit fiche_article(QWidget *parent = 0);
    ~fiche_article();
 
private slots:
    void on_comboBox_currentIndexChanged(const QString &arg1);
 
private:
    Ui::fiche_article *ui;
    QSqlDatabase db;
    QSqlQuery *qry;
    QString *sQuery;
 
 
 
    QSqlQueryModel *model;
    QSqlQueryModel *model2;
 
 
};
 
#endif // FICHE_ARTICLE_H

---

main.cpp :

Code:

---

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

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