Changing data in Qt table view - c++

Question

I went through previous questions on stackoverflow regarding updating table view and Qt tutorial but I still cannot get my code to work. I want to update table view data with setData method when the push button is pressed. The method insertData inside my custom model TableModel gets called but data does not get changed (new rows are added). Where is the problem? I'm not sure if this is relevant but my table view is on qwidget which is on tab widget.
MainWindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "tablemodel.h"
#include <iostream>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
this->dataFetcher = new DataFetcher();
tm = new TableModel(0);
ui->tableView->setModel(tm);
ui->tableView->show();
this->setPushButtonHandlers();
}
MainWindow::~MainWindow()
{
delete ui;
delete this->dataFetcher;
}
void MainWindow::setPushButtonHandlers()
{
connect(this->ui->refreshDataButton, SIGNAL (clicked()), this, SLOT (refreshDataHandler()));
}
void MainWindow::refreshDataHandler()
{
this->tm->insertData();
}
TableModel.cpp
#include "tablemodel.h"
#include <iostream>
TableModel::TableModel(QObject *parent): QAbstractTableModel(parent)
{
}
int TableModel::rowCount(const QModelIndex &parent) const
{
return 2;
}
int TableModel::columnCount(const QModelIndex &parent) const
{
return 16;
}
QVariant TableModel::data(const QModelIndex &index, int role) const
{
if (role == Qt::DisplayRole)
{
return QString("Row%1, Column%2")
.arg(index.row() + 1)
.arg(index.column() +1);
}
return QVariant();
}
QVariant TableModel::headerData(int section, Qt::Orientation orientation, int role) const
{
if (role == Qt::DisplayRole)
{
if (orientation == Qt::Horizontal) {
switch (section)
{
case 0:
return QString("Symbol");
case 1:
return QString("Name");
case 2:
return QString("Stock Exchange");
case 3:
return QString("Trade Price");
case 4:
return QString("Ask");
case 5:
return QString("Bid");
case 6:
return QString("Change");
case 7:
return QString("Change %");
case 8:
return QString("Previous close");
case 9:
return QString("Open");
case 10:
return QString("Days Low");
case 11:
return QString("Days High");
case 12:
return QString("Year Low");
case 13:
return QString("Year High");
case 14:
return QString("Change % From Year Low");
case 15:
return QString("Change % From Year High");
}
} else if (orientation == Qt::Vertical) {
return QVariant(QString::number(section+1));
}
}
return QVariant();
}
void TableModel::insertData()
{
beginInsertRows(QModelIndex(), 3, 100);
endInsertRows();
QModelIndex rv = this->index(1, 1);
setData(rv, 9999);
emit dataChanged(rv, rv);
QString s = data(rv).toString();
std::cout << s.toUtf8().constData() << std::endl;
}

Answer 1

At first you should re-implement insertRows virtual method of QAbstractItemModel. Next, you should refactor your code as following:
void TableModel::insertData()
{
insertRows(rowCount(), 1, QModelIndex());
}
bool TableModel::insertRows(int row, int count, const QModelIndex &index)
{
beginInsertRows();
items.push_back("");
endInsertRows();
return true;
}
QVariant TableModel::data(const QModelIndex &index, int role) const
{
if (index.isValid() && role == Qt::DisplayRole) {
return items.at(index.row());
}
return QVariant();
}
int TableModel::rowCount(const QModelIndex &parent) const
{
return items.size();
}
Also, add the data actually:
class TableModel {
// ...your code...
private:
std::vector<QString> items;
};
This code is just an example code - when moving this to your production code you absolutely should do some changes.