Qt Widgets
Model/View Tutorial
Model/View Programming
Presenting SQL Data in a Table View

Update Model

The model emits signals to indicate changes. For example, dataChanged() is emitted whenever items of data made available by the model are changed. Changes to the headers supplied by the model cause headerDataChanged() to be emitted. If the structure of the underlying data changes, the model can emit layoutChanged() to indicate to any attached views that they should redisplay any items shown, taking the new structure into account.

How to modify the data in the model and update the view when new data is received from external?
How to update a QStringListModel
New in Qt 5.11: improvements to the model/view APIs (part 1)
How to set non-selectable default text on QComboBox?
QComboBox – Select no entry
ComboBox model change does not update graphical appearance every time
The ModelView Architecture

Source

#0  PatientModel::setData () at ../DatabaseSelect/src/business/PatientModel.cpp:188
#1  QAbstractItemModel::setItemData () at itemmodels/qabstractitemmodel.cpp:1912
#2  QComboBox::insertItem () at widgets/qcombobox.cpp:2315
#3  QComboBox::insertItem () at ../../../Qt/5.12.5/gcc_64/include/QtWidgets/qcombobox.h:279
#4  QComboBox::addItem () at ../../../Qt/5.12.5/gcc_64/include/QtWidgets/qcombobox.h:272
#5  PatientListenerComboBox::patientAdded () at ../DatabaseSelect/src/presentation/PatientListenerComboBox.cpp:18
#6  Root::addPatient () at ../DatabaseSelect/src/business/Root.cpp:15
#7  MainWindow::onPatientButtonAddClicked () at ../DatabaseSelect/src/presentation/MainWindow.cpp:164
#8  MainWindow::qt_static_metacall ()::InvokeMetaMethod, _id=3, _a=0x7fffffffd590) at moc_MainWindow.cpp:106
#9  QMetaObject::activate ()
#10 QMetaObject::activate ()::staticMetaObject>,
#11 QAbstractButton::clicked () at .moc/moc_qabstractbutton.cpp:312
#12 QAbstractButtonPrivate::emitClicked () at widgets/qabstractbutton.cpp:414
#13 QAbstractButtonPrivate::click () at widgets/qabstractbutton.cpp:407
#14 QAbstractButton::mouseReleaseEvent () at widgets/qabstractbutton.cpp:1011
#15 QToolButton::mouseReleaseEvent () at widgets/qtoolbutton.cpp:622
#16 QWidget::event () at kernel/qwidget.cpp:9327
#17 QAbstractButton::event () at widgets/qabstractbutton.cpp:968
#18 QToolButton::event () at widgets/qtoolbutton.cpp:1001
#19 QApplicationPrivate::notify_helper () at kernel/qapplication.cpp:3700
#21 QCoreApplication::notifyInternal2 () at kernel/qcoreapplication.cpp:1088
#22 QCoreApplication::sendSpontaneousEvent () at kernel/qcoreapplication.cpp:1488
#23 QApplicationPrivate::sendMouseEvent ()
#24 QWidgetWindow::handleMouseEvent () at kernel/qwidgetwindow.cpp:663
#25 QWidgetWindow::event () at kernel/qwidgetwindow.cpp:281
#26 QApplicationPrivate::notify_helper () at kernel/qapplication.cpp:3700
#27 QApplication::notify () at kernel/qapplication.cpp:3446
#28 QCoreApplication::notifyInternal2 () at kernel/qcoreapplication.cpp:1088
#29 QCoreApplication::sendSpontaneousEvent () at kernel/qcoreapplication.cpp:1488
#30 QGuiApplicationPrivate::processMouseEvent () at kernel/qguiapplication.cpp:2107
#31 QGuiApplicationPrivate::processWindowSystemEvent () at kernel/qguiapplication.cpp:1842.
#32 QWindowSystemInterface::sendWindowSystemEvents () at kernel/qwindowsysteminterface.cpp:1151
#33 xcbSourceDispatch () at qxcbeventdispatcher.cpp:105
#34 g_main_context_dispatch () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#35 ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#36 g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#37 QEventDispatcherGlib::processEvents () at kernel/qeventdispatcher_glib.cpp:422
#38 QEventLoop::exec () at kernel/qeventloop.cpp:225
#39 QCoreApplication::exec () at kernel/qcoreapplication.cpp:1389
#40 main () at ../DatabaseSelect/src/main.cpp:55

Model

`Qt/5.12.3/Src/qtbase/src/corelib/itemmodels/qabstractitemmodel.h`

`Qt/5.12.3/Src/qtbase/src/gui/itemmodels/qstandarditemmodel.h`

class QStandardItemPrivate
{
    [...]

    QStandardItemModel *model;
    QStandardItem *parent;
    QVector<QStandardItemData> values;
    QVector<QStandardItem*> children;
    int rows;
    int columns;

    QStandardItem *q_ptr;

    [...]
};

void
QStandardItemModel::setItem(int row,
                            int column,
                            QStandardItem *item)
{
    Q_D(QStandardItemModel);
    d->root->d_func()->setChild(row, column, item, true);
}

void
QStandardItemPrivate::setChild(int row,
                               int column,
                               QStandardItem *item,
                               bool emitChanged)
{
    [...]
}

QVariant
QStandardItemModel::data(const QModelIndex &index,
                         int role) const
{
    Q_D(const QStandardItemModel);
    QStandardItem *item = d->itemFromIndex(index);
    return item ? item->data(role) : QVariant();
}

QVariant
QStandardItem::data(int role) const
{
    Q_D(const QStandardItem);
    role = (role == Qt::EditRole) ? Qt::DisplayRole : role;
    QVector<QStandardItemData>::const_iterator it;
    for (it = d->values.begin(); it != d->values.end(); ++it) {
        if ((*it).role == role)
            return (*it).value;
    }
    return QVariant();
}

void
QStandardItem::setRowCount(int rows)
{
    int rc = rowCount();
    if (rc == rows)
        return;
    if (rc < rows)
        insertRows(qMax(rc, 0), rows - rc);
    else
        removeRows(qMax(rows, 0), rc - rows);
}

void
QStandardItem::insertRows(int row,
                          const QList<QStandardItem*> &items)
{
    Q_D(QStandardItem);
    if (row < 0)
        return;
    d->insertRows(row, items);
}

bool
QStandardItemPrivate::insertRows(int row,
                                 int count,
                                 const QList<QStandardItem*> &items)
{
    [...]

    if (model)
        model->d_func()->rowsAboutToBeInserted(q, row, row + count - 1);

    [...]

    if (model)
        model->d_func()->rowsInserted(q, row, count);

    return true;
}

View

`Qt/5.12.3/Src/qtbase/src/widgets/widgets/qcombobox.h`

`Qt/5.12.5/Src/qtbase/src/widgets/itemviews/qabstractitemview.h`

/*!
    This slot is called when items with the given \a roles are changed in the
    model. The changed items are those from \a topLeft to \a bottomRight
    inclusive. If just one item is changed \a topLeft == \a bottomRight.

    The \a roles which have been changed can either be an empty container (meaning everything
    has changed), or a non-empty container with the subset of roles which have changed.
*/
void QAbstractItemView::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles)
{
    [...]
}

`Qt/5.12.5/Src/qtbase/src/widgets/itemviews/qtreeview.h`

/*!
  \reimp
*/
void QTreeView::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles)
{
    [...]
    QAbstractItemView::dataChanged(topLeft, bottomRight, roles);
}

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Qt QTableView / QAbstractTableModel / QTextTable

Example

Documentation / Class

Merge cells

Column/Row resize

Focus Rectangle / Border Selection

Row Height / Column Width

Hide Vertical Header

Hide Column

Add QWidget or custom Painting in TableView

Alignment

Header