QSqlRelationalDelegate-subclass-for-QSqlRelationalTableModel

QSqlRelationalDelegate subclass that works with QSqlRelationalTableModel

When you are using a QSqlRelationalTableModel in combination with QSortFilterProxyModel, you lose the automatic combobox that is displayed in a QTableView.

This is a subclass of QSqlRelationalDelegate, that works:

COMMENT: To use it with another proxy model (my own QXTreeProxyModel that converts a table to a tree that can be displayed by QTreeView), I replaced QSortFilterProxyModel by QAbstractProxyModel throughout the code in mysqlrelationaldelegate.cpp; no other changes were necessary. BTW, QXTreeProxyModel is available on https://github.com/Al-/QXTreeProxyModel

Header:

<br />#ifndef MYSQLRELATIONALDELEGATE_H<br />#define MYSQLRELATIONALDELEGATE_H

#include &lt;QSqlRelationalDelegate&amp;gt;

class mySqlRelationalDelegate : public QSqlRelationalDelegate<br />{<br /> Q_OBJECT<br />public:<br /> explicit mySqlRelationalDelegate(QObject *parent = 0);

QWidget *createEditor(QWidget *aParent, const QStyleOptionViewItem &amp;option, const QModelIndex &amp;index) const;<br /> void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &amp;index) const;<br /> void setEditorData(QWidget *editor, const QModelIndex &amp;index) const;

signals:

public slots:

};

#endif // MYSQLRELATIONALDELEGATE_H<br />

Source:


#include "mysqlrelationaldelegate.h"
#include <QSqlRelationalTableModel&gt;
#include <QSortFilterProxyModel&gt;

1. include <QDebug&gt;
   #include <QSqlRecord&gt;

mySqlRelationalDelegate::mySqlRelationalDelegate(QObject *parent) :
QSqlRelationalDelegate (parent)
{
}

QWidget *mySqlRelationalDelegate::createEditor(QWidget *aParent, const QStyleOptionViewItem &option, const QModelIndex &index) const {

const QSqlRelationalTableModel sqlModel = qobject_cast&lt;const QSqlRelationalTableModel>(index.model());
QSqlTableModel childModel = sqlModel ? sqlModel->relationModel(index.column()) : 0;
if (!childModel )
{
const QSortFilterProxyModel proxyModel = qobject_cast&lt;const QSortFilterProxyModel >(index.model());
if (proxyModel)
{
sqlModel = qobject_cast&lt;const QSqlRelationalTableModel>(proxyModel->sourceModel());
childModel = sqlModel ? sqlModel->relationModel(index.column()) : 0;
}
}

if (!childModel)
{
return QItemDelegate::createEditor(aParent, option, index);
}

QComboBox combo = new QComboBox(aParent);
combo->setModel(childModel);
combo->setModelColumn(childModel->fieldIndex(sqlModel->relation(index.column()).displayColumn()));
combo->installEventFilter(const_cast&lt;mySqlRelationalDelegate>(this));

return combo;

}

void mySqlRelationalDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
QString strVal = "";
const QSqlRelationalTableModel sqlModel = qobject_cast&lt;const QSqlRelationalTableModel>(index.model());
if (!sqlModel )
{
const QSortFilterProxyModel* proxyModel = qobject_cast&lt;const QSortFilterProxyModel *>(index.model());
if (proxyModel) {
strVal = proxyModel->data(index).toString();
}
} else {
strVal = sqlModel->data(index).toString();
}

QComboBox combo = qobject_cast&lt;QComboBox>(editor);
if (strVal.isEmpty() || !combo) {
QItemDelegate::setEditorData(editor, index);
return;
}

combo->setCurrentIndex(combo->findText(strVal));
}

void mySqlRelationalDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
if (!index.isValid())
return;

QSqlRelationalTableModel sqlModel = qobject_cast&lt;QSqlRelationalTableModel>(model);
QSortFilterProxyModel* proxyModel = NULL;
if (!sqlModel )
{
proxyModel = qobject_cast&lt;QSortFilterProxyModel >(model);
if (proxyModel)
sqlModel = qobject_cast&lt;QSqlRelationalTableModel>(proxyModel->sourceModel());
}

QSqlTableModel *childModel = sqlModel ? sqlModel->relationModel(index.column()) : 0;
QComboBox combo = qobject_cast&lt;QComboBox>(editor);
if (File:SqlModelchildModel || !combo) {
QItemDelegate::setModelData(editor, model, index);
return;
}

int currentItem = combo->currentIndex();
int childColIndex = childModel->fieldIndex(sqlModel->relation(index.column()).displayColumn());
int childEditIndex = childModel->fieldIndex(sqlModel->relation(index.column()).indexColumn());

if (proxyModel) {
proxyModel->setData(index, childModel->data(childModel->index(currentItem, childColIndex), Qt::DisplayRole), Qt::DisplayRole);
proxyModel->setData(index, childModel->data(childModel->index(currentItem, childEditIndex), Qt::EditRole), Qt::EditRole);
} else {
sqlModel->setData(index, childModel->data(childModel->index(currentItem, childColIndex), Qt::DisplayRole), Qt::DisplayRole);
sqlModel->setData(index, childModel->data(childModel->index(currentItem, childEditIndex), Qt::EditRole), Qt::EditRole);
}
}