Click to Update Database, from editable QAbstractTableModel - c++

Question

An editable table view is connected to a custom model (a subclass of QAbstractTableModel) that populates it from a database. The table view's edited values are temporarily held in a 2D QVector.
The goal is for a push button below the table view to trigger an update of the database.
The problem is that I can't seem to figure out the SIGNAL&SLOT mechanism for this. It seems to be a problem of the scope of the push button, I think, but I don't know how to fix it.
First two files just for overview, the problem is (probably) in the third, in setData().
I'm still a beginner in this framework so apologies for a potentially silly question.
a tableView("menuTable") and a pushButton("menuTableUpdateButton") are made in Design Mode.
mainwindow.cpp (opening a db conection, querying db, placing result into QVector and initializing and assigning the model)
...
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
//database connection
...
//opening database
if(db.open())
{
...
//2D array to hold the query to pass into model
QVector< QVector<QString> > sqlQueryVector;
...
//querying and storing the result
...
//initialize QAbstractTableModel and pass it into the menu table
//passing an id(int) and a 2D QVector that holds the sql query result to the model
menuTableModel* modelMenu = new menuTableModel(id, sqlQueryVector);
ui->menuTable->setModel(modelMenu);
}
else
{
...
}
}
menutablemodel.h (basic initializations)
#ifndef MENUTABLEMODEL_H
#define MENUTABLEMODEL_H
#include <QAbstractTableModel>
#include <QVector>
class menuTableModel : public QAbstractTableModel
{
Q_OBJECT
public:
explicit menuTableModel(const int &monId, const QVector< QVector<QString> > &qry, QObject *parent = 0)
: QAbstractTableModel(parent), mondayId(monId),query(qry) {}
int rowCount(const QModelIndex &parent = QModelIndex()) const ;
int columnCount(const QModelIndex &parent = QModelIndex()) const;
QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
QVariant headerData(int section, Qt::Orientation orientation, int role) const;
bool setData(const QModelIndex & index, const QVariant & value, int role = Qt::EditRole);
Qt::ItemFlags flags(const QModelIndex & index) const ;
void setQuery(const QVector< QVector<QString> > &query);
void setId(const int &stId);
private:
int mondayId;
QVector< QVector<QString> > query;
signals:
void editCompleted(const QString &);
slots:
void updateDatabase();
};
#endif // MENUTABLEMODEL_H
menutablemodel.cpp (assigning data into table, editing and SAVING TO DATABASE)
#include "menutablemodel.h"
#include <QDebug>
#include <QSqlQuery>
int menuTableModel::rowCount(const QModelIndex & /*parent*/) const {...}
int menuTableModel::columnCount(const QModelIndex & /*parent*/) const {...}
QVariant menuTableModel::data(const QModelIndex &index, int role) const {...}
QVariant menuTableModel::headerData(int section, Qt::Orientation orientation, int role) const {...}
//edit and save into database
bool menuTableModel::setData(const QModelIndex & index, const QVariant & value, int role)
{
if (role == Qt::EditRole)
{
query[index.row()][index.column()] = value.toString();
QString result;
for(int row= 0; row < query.size(); row++)
{
for(int col= 0; col < query[0].size(); col++)
{
result += query[row][col] + " ";
}
}
emit editCompleted( result );
qDebug() << "result is: " << result;
//update database here with connect??
//connect(menuTableUpdateButton, SIGNAL (clicked()), this, SLOT (updateDatabase()));
}
return true;
}
Qt::ItemFlags menuTableModel::flags(const QModelIndex & /*index*/) const {...}
void menuTableModel::setQuery(const QVector< QVector<QString> > &qry) {
query = qry;
}
void menuTableModel::setId(const int &stId) {...}
void menuTableModel::updateDatabase() {
//write SqlQuery here
...
}
My main question is where and how do I define the SIGNAL&SLOT command to connect the button being clicked to executing an SQL query to the database?

Answer 1

In your MainWindow constructor, you have the model and the button, so that's the best place to connect them:
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
//opening database
if(db.open()) {
//...
menuTableModel* modelMenu = new menuTableModel(id, sqlQueryVector);
ui->menuTable->setModel(modelMenu);
// Connect button click to model update
connect(ui->menuTableUpdateButton, SIGNAL(clicked()),
modelMenu, SLOT(updateDatabase()));
}
}