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.

[Risver]

@JonB
I can just upgrade Qt to v6 and see if it works

[JonB]

@Risver
You can indeed, though my personal preference would be to take the latest Qt5.x release. I still see too many issues with Qt6, not to mention that I think they still have not ported all modules, depends what bits you will be using.

However, my learned colleagues may disagree and advise you to go for Qt6, i don't know....

[Risver]

@JonB
I'm installing Qt 6 for now, i will check if everything works. If it won't i will install Qt 5.15

Okay, I configured the project in the new Qt and i still have the same error.

[jsulm]

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

I configured the project in the new Qt and i still have the same error.

And you are sure you're building with Qt6 now?
And did you do a complete rebuild?

[Risver]

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

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

I configured the project in the new Qt and i still have the same error.

And you are sure you're building with Qt6 now?
And did you do a complete rebuild?

Yes i'm sure i building with Qt6, but i'm not sure how can i complete rebuild the project.
found this. Still have error

[mchinand]

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

The QT version is 5.0.2

I'm guessing 5.0.2 is/was your QtCreator version (the IDE) not the version of Qt. Look at the 'Kit' you are using, it will say what version of Qt you are using.

[Christian Ehrlicher]

querymodel->removeRow(addressId, 1);

model->removeRows(row, 1);

removeRow() != removeRows()

[Risver]

@mchinand
Yes you're right.

[Risver]

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

querymodel->removeRow(addressId, 1);

model->removeRows(row, 1);

removeRow() != removeRows()

Thank You Christian, now i have no errors, but it is not removing.

[JonB]

@Risver
@Christian-Ehrlicher's comment above is why your line querymodel->removeRow(addressId, 1); is generating an error. Look at the two different methods he has given you links to.

[JonB]

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

Thank You Christian, now i have no errors, but it is not removing.

Start by showing us your new line, because we don't know which of the two methods you changed to using and what parameters you gave it.

[Risver]

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

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

Thank You Christian, now i have no errors, but it is not removing.

Start by showing us your new line, because we don't know which of the two methods you changed to using and what parameters you gave it.

i've changed only this one:

void MainWindow::on_remove_clicked()
{
    if (ui->tableView->selectionModel()->hasSelection())
    {
        int addressId = ui->tableView->selectionModel()->currentIndex().row();
        querymodel->removeRows(addressId, 1);
    }
}

[JonB]

@Risver

qDebug() << querymodel->rowCount();
qDebug() << querymodel->removeRows(addressId, 1);
qDebug() << querymodel->rowCount();

[Risver]

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

@Risver

qDebug() << querymodel->rowCount();
qDebug() << querymodel->removeRows(addressId, 1);
qDebug() << querymodel->rowCount();

The rowCount is always 3 and the removeRows is false.

[Christian Ehrlicher]

Does your table has a primary key? Otherwise removing will not work.

[Risver]

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

Does your table has a primary key? Otherwise removing will not work.

Yes, it has.

[JonB]

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

Does your table has a primary key? Otherwise removing will not work.

That's very interesting. I assume we're talking about a SQL table model here? I looked through the docs (briefly) but did not see any mention of this requirement, is it documented?

[Risver]

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

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

Does your table has a primary key? Otherwise removing will not work.

That's very interesting. I assume we're talking about a SQL table model here? I looked through the docs (briefly) but did not see any mention of this requirement, is it documented?

That is how my SQL Table looks.

[JonB]

@Risver

qDebug() << querymodel->removeRows(addressId, 1);

Please add qDebug() << addressId, we need to make sure what that is, just in case.....

[Risver]

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

@Risver

qDebug() << querymodel->removeRows(addressId, 1);

Please add qDebug() << addressId, we need to make sure what that is, just in case.....

It is a variable to store the selected row, for example when i select the first row, it returns 0.
I checked this and its working fine