QProgressBar: don't understand in details, help me !!!

Hi all,

I begin to write a simple application that load data from database and I want to use QProgressBar but I don't know exactly how it works, pls show it for me in details.

Thanks in advance.

It is very easy to use one.
Create it,put it in a layout, set it's max and min value, and then call setValue to update it.
You also can look at QProgressDialog beacuse it uses a QProgressBar.

Regards

In my program, I want to connect to database that verify user input, please tell me how to make progressbar describe this progress.

Beforehands thanks.

Anh.:)

Everything you need to know is simple:

1) Create QProgressBar
2) setMin setMAx
3) setValue according to some sort of SIGNAL, like if database connected maybe connect a function to add like 20 more % to progressbar
Take a look at examples in your Qt folder, like HTTP or FTP example.

Quote:

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Originally Posted by haconganh

In my program, I want to connect to database that verify user input, please tell me how to make progressbar describe this progress.

Beforehands thanks.

Anh.:)

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QProgressDialog *dlg = new QProgressDialog(0,Qt::Popup);

here is a sample wo user can not stop dlg->setCancelButton(0); && query... result is a dump file

Code:

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void ExportSql()
{
    if (OSWinServer()) {
    table = table.toUpper();  /* bastard win ! */
    }
 
    QDate nowtaga = QDate::currentDate();
    bool ok;
    QString ba = nowtaga.toString("d.M.yyyy")+"_"+table+".sql";
 
    QString cfileName = QFileDialog::getSaveFileName(this, "Export MYSQL table format",ba, "*.sql");
    if (cfileName.size() > 0 && cfileName !=ba ) {
                 if (!cfileName.endsWith(".sql")) {
                     cfileName = cfileName+".sql"; 
                 }
    } else {
    return;
    }
 
     QProgressDialog *dlg = new QProgressDialog(0,Qt::Popup);
            dlg->setLabelText (tr("Export table \"%1\" from %2").arg( table ).arg(db.hostName()));
            dlg->setCancelButton(0);
            //////dlg->setMaximum(100);
            //////dlg->setValue(0);
 
 
 
    qDebug() << "### ExportSql " << table;
    QDate nowtag = QDate::currentDate();
    QSqlQuery query(QString("SELECT * FROM %1").arg(table),db);
    QSqlRecord rec = query.record();
    QStringList cvslines;
    QStringList Fname;
    QStringList Fvalue;
    cvslines.clear();
    cvslines.append(QString("\n###### table %1\n\n").arg(table));
    cvslines.append(QString("\n###### date %1\n\n").arg(nowtag.toString("d.M.yyyy")));
 
    bool suppoaffect;
            int sumcol = rec.count();
            int sumrow = query.numRowsAffected();
            int recnum = 0;  /* QProgressDialog *dlg; */
            int pasero = 0;
 
 
             while (query.next()) { 
                    recnum++;  /* count fake lines */
                     dlg->setMaximum(100);
                     dlg->setValue((recnum * 100) / sumrow );
                    Fvalue.clear();
                    Fname.clear();
 
                             for(int i=0;i<sumcol;i++){
                             bool oknr = false;
                             QSqlField fld = rec.field(i);
                             QString value = sql_Quote(query.value(i).toString());
                                     value = value.replace("\n","\\n");
                                     value = value.replace("\t","\\t");
                                     value = value.replace("\r","\\r");
                             const QString typeoffield = QString(QVariant::typeToName(fld.type()));
                                 if ( typeoffield == "int" ) {
                                    int vnummer = value.toInt(&oknr);
                                 }
                             QString fname = sql_Quote(rec.fieldName(i));
                                 if (oknr) {
                                 Fvalue.append(value);
                                 } else if (value.isEmpty()) {
                                 Fvalue.append(DefaultFieldFrom(table,fname));
                                 } else {
                                 Fvalue.append(QString("'%1'").arg(value));  
                                 }
                             }
 
                    QString Dvalue = Fvalue.join(",");
                    cvslines.append(QString("REPLACE INTO %1 VALUES (%2);\n").arg(table).arg(Dvalue));
                    }
                   dlg->close();
 
           cvslines.append(QString("\n"));
 
 
    QString stream = SqlCreateTable();
            stream.append(cvslines.join(""));
 
    /////////qDebug() << "### stream " << stream;
        QFile f( cfileName );
        if ( f.open( QFile::WriteOnly | QFile::Text ) )
        {
        QTextStream sw( &f );
        sw << stream;
        f.close();
        } else {
            QMessageBox::warning(this, tr("Error SQL File!"),tr("Unable to write on this file ..."));
        } 
 
}
 
 
QString DefaultFieldFrom( const QString table , const QString field )
{
    const QString xdefault = "NULL";
    QSqlQuery query(QString("SHOW COLUMNS FROM %1").arg(table),db_0);
    QSqlRecord rec = query.record();
    int sumcol = rec.count();
           while (query.next()) { 
              QString feldname = query.value(0).toString();
                  if ( feldname  == field ) {
                      QString svl = query.value(4).toString(); 
                      if (svl.size() < 1) {
                        return xdefault;
                      } else {
                        return  svl; 
                      }
 
                  }
 
            }
 
return xdefault;
}

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Hi patrik08,

With your code, I understand it exactly now,
thank patrik08 a lot :)