Deleting row from QTableWidget and from Sqlite database

Risver

Hi, I have a QTableWidget which is loading data from my Sqlite database. I need to make a delete selected row mechanism, but i don't know how to do this. Please help.

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QObject>
#include <QMainWindow>
#include <QSqlQueryModel>
#include <QHeaderView>

#include "signup.h"
#include "login.h"
#include "dbmanager.h"


QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

public slots:
    void nextWindow(QString);

private slots:
    void on_login_clicked();
    void on_signup_clicked();
    void on_remove_clicked();

    void on_tableWidget_cellClicked(int row, int column);

private:
    //Ui::MainWindow *ui;
    login * m_logWindow{nullptr};
    signup * m_regWindow{nullptr};
    QSqlQueryModel * querymodel;

    void readList(QString);
    QString Bufferbase;

    QSqlDatabase m_db;
    QSqlQuery qry;

protected:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this); 
    setWindowFlags(Qt::MSWindowsFixedSizeDialogHint);

    m_logWindow = new login(this);
    m_regWindow = new signup(this);

    connect(m_logWindow,&login::LoginSuccess, this, &MainWindow::nextWindow);
}

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

void MainWindow::on_login_clicked()
{
    m_logWindow->show();
}

void MainWindow::on_signup_clicked()
{
    m_regWindow->show();
}

void MainWindow::nextWindow(QString base)
{
    ui->stackedWidget->setCurrentIndex(1);
    readList(base);
    Bufferbase = base;
}

void MainWindow::readList(QString base)
{
    m_db.setDatabaseName("DiffPass.sqlite");

    QSqlQuery qry(m_db);
    QString sBuffer = "SELECT * FROM "+base;
    qry.exec(sBuffer);

    ui->tableWidget->setColumnCount(3);
    QStringList labels;
    labels << "Url" << "E-mail" << "Password";
    ui->tableWidget->setHorizontalHeaderLabels(labels);

    int rowCount = 0;
    while(qry.next())
    {
        ui->tableWidget->insertRow(rowCount);
        QTableWidgetItem * url = new QTableWidgetItem;
        QTableWidgetItem * email = new QTableWidgetItem;
        QTableWidgetItem * password = new QTableWidgetItem;

        url->setText(qry.value(1).toString());
        email->setText(qry.value(1).toString());
        password->setText(qry.value(1).toString());

        ui->tableWidget->setItem(rowCount, 0, url);
        ui->tableWidget->setItem(rowCount, 1, email);
        ui->tableWidget->setItem(rowCount, 2, password);

        rowCount++;
    }
}

void MainWindow::on_remove_clicked()
{
    
}

Thank you in advance!

jsulm

@Risver Why don't you use QTableView with a proper model?

Back to your question: what exactly are you asking? To delete a row from a table in a SQL database you use https://www.w3schools.com/sql/sql_delete.asp . So, what is unclear?

Risver

@jsulm
I read that in QTableView you cannot delete the rows.
Yes, I know that i can use SQL query but i need to deleting the row after index. For example when i delete the 1 row, the second row will be the first with id = 2.

jsulm

@Risver said in Deleting row from QTableWidget and from Sqlite database:

I read that in QTableView you cannot delete the rows

Because that is the job of the model, not view.
See https://doc.qt.io/qt-5/qsqltablemodel.html#removeRows

Risver

@jsulm
Okey i swapped the QTableWidget to QTableView. Now it looks like:

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this); 
    setWindowFlags(Qt::MSWindowsFixedSizeDialogHint);

    m_logWindow = new login(this);
    m_regWindow = new signup(this);

    connect(m_logWindow,&login::LoginSuccess, this, &MainWindow::nextWindow);
}

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

void MainWindow::on_login_clicked()
{
    m_logWindow->show();
}

void MainWindow::on_signup_clicked()
{
    m_regWindow->show();
}

void MainWindow::nextWindow(QString base)
{
    ui->stackedWidget->setCurrentIndex(1);
    readList(base);
    Bufferbase = base;
}

void MainWindow::readList(QString base)
{
    m_db.setDatabaseName("DiffPass.sqlite");

    QSqlQuery qry(m_db);
    QString sBuffer = "SELECT * FROM "+base;
    qry.exec(sBuffer);

    querymodel = new QSqlQueryModel();
    querymodel -> setQuery(sBuffer);
    ui -> tableView -> setModel(querymodel);
}

void MainWindow::on_remove_clicked()
{
    
}

And now how can i detect the selected row signal ?

jsulm

@Risver said in Deleting row from QTableWidget and from Sqlite database:

And now how can i detect the selected row signal ?

What about https://doc.qt.io/qt-5/qtableview.html#selectionChanged ?

Risver

@jsulm
Okay and how can i connect it with the button_clicked signal?

Christian Ehrlicher

@Risver said in Deleting row from QTableWidget and from Sqlite database:

Okay and how can i connect it with the button_clicked signal?

You won't
When you react on the button clicked signal, get the current selection from the view and delete the selected rows in the model.

Risver

@Christian-Ehrlicher said in Deleting row from QTableWidget and from Sqlite database:

@Risver said in Deleting row from QTableWidget and from Sqlite database:

Okay and how can i connect it with the button_clicked signal?

You won't
When you react on the button clicked signal, get the current selection from the view and delete the selected rows in the model.

Something like this ?

void MainWindow::on_remove_clicked()
{
    int selectedRow = ui->tableView->selectionModel()->currentIndex().row();
    
}

Christian Ehrlicher

@Risver Yes.

Risver

@Christian-Ehrlicher
Now when i'm trying to implement QSqlTableModel::deleteRowFromTable the debugger says the deleteRowFromTable is a protected member of QSqlTableModel

jsulm

@Risver https://doc.qt.io/qt-5/qsqltablemodel.html#removeRows

Risver

@jsulm
Could you give some example ?

jsulm

@Risver Example?

model->removeRows(row, 1);

Risver

@jsulm
Now i have error - reference to type 'const QModelIndex' could not bind to an rvalue of type 'int'.
I think i have to refer to QModelIndex but i don't know how. I have a QSqlQueryModel. Should i change it to QAbstractTableModel ?

jsulm

@Risver Please show how you're calling removeRows
And what Qt version do you use?

Risver

@jsulm

void MainWindow::on_remove_clicked()
{

    if (ui->tableView->selectionModel()->hasSelection())
    {
        int addressId = ui->tableView->selectionModel()->currentIndex().row();
        querymodel->removeRow(addressId, 1);
        qDebug() << addressId;
    }
}

The QT version is 5.0.2

jsulm

@Risver said in Deleting row from QTableWidget and from Sqlite database:

QT version is 5.0.2

Check the documentation for removeRows() in that Qt version.
Probably it has a different signature.

Is there a reason why you're using such an ancient version?

Risver

@jsulm said in Deleting row from QTableWidget and from Sqlite database:

Is there a reason why you're using such an ancient version?

I just installed it a while time ago.

JonB

@Risver said in Deleting row from QTableWidget and from Sqlite database:

I just installed it a while time ago.

Before you spend any more time on this. Qt5 is already up to 5.15, unless you have some deep reason for wanting 5.0 I would uninstall and get such an up-to-date version.