You have to replace string line
QString line = in.readLine();
into while:
QFile file("/home/hamad/lesson11.txt");
if(!file.open(QIODevice::ReadOnly)) {
QMessageBox::information(0, "error", file.errorString());
}
QTextStream in(&file);
while(!in.atEnd()) {
QString line = in.readLine();
QStringList fields = line.split(",");
model->appendRow(fields);
}
file.close();