How to pass data from one tab to another.

[pavel213]

Hello Everyone,
I am learning Qt and stuck on below problem.
I have a gui which have more than 10 tabs. I have created one new tab. In that new tab I am using QtLineEdit. I want to fill this QtLineEdit with data from another tab's QTableView.
Any help would be appreciated.
Thanks.

[jsulm]

@pavel213 Well, you have access to all your widgets in same parent widget via ui->, so simply access what is needed using ui->NAME_OF_WIDGET_OBJECT.

[pavel213]

@jsulm Thanks for reply. Would you please elaborate your answer. I don't have much experience in qt.

[jsulm]

@pavel213 Do you use QtDesigner to design your UI?
If you do, then you can access ALL your widgets using ui->:

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->lineEdit->setText("Some text");
}

[CP71]

@pavel213
Hi,
well, you have several ways to do this, much depends on the type of data ( temporary data, data that your core application uses, ... ).

As jsulm says you have access to all widgets, so from the parent you can get data from a tab and give them to other tab/tabs.
MyData data = ui->tab1->getMyData()
ui->tab2->setMyData(data)

Via signals, when data changes you can emit a signal with the new value/s.
connect( ui->tab1, SIGNAL( myDataChange( MyData ), ui->tab2, SLOT( newValueData(MyData) ); // For example I use old style connect

Via data manager, if your data is data useful for your core application.
In the tab1: CoreDataManager->setMyData( data );
In the tab2: data = CoreDataManager->getMyData( );

and so on.

As I already say, much depends on the type of data and how you use them.

[pavel213]

Gui is built in VS 2015 and qt 5.9.9.

Following is the code snippet.
From this tab "MultitranpondersTab" i want to pick data "a_list".

void MultiTranspondersTab::cycle()
{
    QByteArray answer, uid;
	bool gotAnswer;
	ST25R3911ComError err;
	QList<Card*> card_list;

	gotAnswer = true;

	err = this->com->antennaEnableRFField(true);
    if (err)
    {
        emit mainWindowDisplayMessage("ext field detected, not polling");
        goto end_scan;
    }

	onTriggerProgressBar();
	SleepThread::msleep(10);

	if(this->isoA_cb->isChecked())
	{
		int counter = 10;
		QList<Iso14443aCard> a_list;

        com->kovioInitialise();
        err = com->kovioRead(uid);
        com->kovioDeinit(true);
        if (ST25R3911ComError::NoError == err)
        {
            if (uid.size() > 0) {
                // avoid the "kovio situation"
                Card *card = new Card(uid, QString("Kovio BC"));
                card_list.append(card);
            }
            else
            {
                emit mainWindowDisplayMessage("problem receiving data..");
            }
            goto end_scan; // no sense to continue to other protocols since Kovio barcode will screw all other communications
        }
        this->com->iso14443aInit();
		onTriggerProgressBar();
		do 
		{
			counter--;
			gotAnswer = false;
            int list_size = a_list.size(); /* list_size is a Workaround for early AS3953 versions which did not recognize HLTA command */
            if (itsAnalogState)
            {
                SleepThread::msleep(delay_sb->value());
            }
			err = this->com->iso14443aREQA(&a_list, uid);

			if(err == ST25R3911ComError::NoError && a_list.size()>list_size)
			{

and following is the tab where i want to use it:

WiegandTab::WiegandTab(ST25R3911Communication* com, QWidget *parent)
	: QWidget(parent)
	, itsCom(com)
	, itsCurrentCardRow(0)
{
	this->setupUi(this);
	
 

    
	this->txrx_pb->setEnabled(true);
}

void WiegandTab::on_txrx_pb_clicked(bool clicked)
{
	/*if (felicaCardsTw->rowCount() < 0)
		return;*/
	WiegandTab wTabObj;
	ST25R3911ComError err;
	QByteArray wiegandData, fc, cid, rx;
	const QByteArray	tempCard;
	int w_frmt;
	bool ok;
	QString format = this->comboBox->currentText();
	
	w_frmt = format.split(" ").last().toInt(&ok, 16);

#if QT_VERSION < 0x050000
	fc = QByteArray::fromHex(this->txbytes_le->text().toAscii());
	cid = QByteArray::fromHex(this->txbytes_le_2->text().toAscii());
#else
	fc = QByteArray::fromHex(this->txbytes_le->text().toLatin1());
	cid = QByteArray::fromHex(this->txbytes_le_2->text().toLatin1());
#endif
	
	//some where here i want to use "a_list" 
        // basically want to put "a_list" data in  "txbytes_le_2"

	/*if (item && this->idm_box->isChecked())
	{
#if QT_VERSION < 0x050000
		idm = QByteArray::fromHex(item->text().toAscii());
#else
		idm = QByteArray::fromHex(item->text().toLatin1());
#endif
	}*/

	//qDebug() << "wiegandTxRxNBytes() idm =" << idm.toHex();

	wiegandData.append(w_frmt);
	wiegandData.append(fc);
	wiegandData.append(cid);

	qDebug() << "wiegandTxRxNBytes() tx =" << wiegandData.toHex();

	err = itsCom->wiegandTxRxNBytes(wiegandData, rx);
	if (err == ST25R3911ComError::NoError)
	{
		//rxbytes_le->setText(rx.toHex());
	}
	emit mainWindowDisplayMessage(QString("wiegandTxRxNBytes[%1]").arg(itsCom->decodeFWError(err)) + wiegandData.toHex() + "->" + rx.toHex());
}

[CP71]

@pavel213
If I have well understood your code a_list is a local QList (MultiTranspondersTab class), it is declared in the function body. So the only way I see is sending a copy of data to another tab (WiegandTab class) via connect, see the previous post.

[CP71]

@pavel213
Only for example:

In MultiTranspondersTab.h :

signals
void sendIsoData(QList<Iso14443aCard>);

In WiegandTab.h :

public slots:
void onNewIsoData(QList<Iso14443aCard>);

in parent of MultiTranspondersTab.h and onNewIsoData:
connect( pMultiTranspondersTab, &MultiTranspondersTab::sendIsoData, pWiegandTab, &WiegandTab::onNewIsoData );

In MultiTranspondersTab.cpp
somewhere in MultiTranspondersTab::cycle() you have to write emit sendIsoData(a_list);