Unsolved QSqlRelationalTableModel doesn't give relation foreign key with Qt::EditRole
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Consider the Qt's example "RelationalTableModel".
#include <QtWidgets> #include <QtSql> #include "../connection.h" #include <QDebug> #include <memory> void initializeModel(QSqlRelationalTableModel *model) { //! [0] model->setTable("employee"); //! [0] model->setEditStrategy(QSqlTableModel::OnManualSubmit); //! [1] model->setRelation(2, QSqlRelation("city", "id", "name")); //! [1] //! [2] model->setRelation(3, QSqlRelation("country", "id", "name")); //! [2] //! [3] model->setHeaderData(0, Qt::Horizontal, QObject::tr("ID")); model->setHeaderData(1, Qt::Horizontal, QObject::tr("Name")); model->setHeaderData(2, Qt::Horizontal, QObject::tr("City")); model->setHeaderData(3, Qt::Horizontal, QObject::tr("Country")); //! [3] model->select(); } std::unique_ptr<QTableView> createView(const QString &title, QSqlTableModel *model) { //! [4] std::unique_ptr<QTableView> view{new QTableView}; view->setModel(model); view->setItemDelegate(new QSqlRelationalDelegate(view.get())); //! [4] view->setWindowTitle(title); QObject::connect(view.get()->selectionModel(), &QItemSelectionModel::selectionChanged, [=](const QItemSelection &selected, const QItemSelection &deselected){ for (const QModelIndex &idx : selected.indexes()) { qDebug() << "DisplayRole:" << model->index(idx.row(), idx.column(), QModelIndex()).data(Qt::DisplayRole); qDebug() << "EditRole" << model->index(idx.row(), idx.column(), QModelIndex()).data(Qt::EditRole); } qDebug() << '\n'; }); return view; } void createRelationalTables() { QSqlQuery query; query.exec("create table employee(id int primary key, name varchar(20), city int, country int)"); query.exec("insert into employee values(1, 'Espen', 5000, 47)"); query.exec("insert into employee values(2, 'Harald', 80000, 49)"); query.exec("insert into employee values(3, 'Sam', 100, 1)"); query.exec("create table city(id int, name varchar(20))"); query.exec("insert into city values(100, 'San Jose')"); query.exec("insert into city values(5000, 'Oslo')"); query.exec("insert into city values(80000, 'Munich')"); query.exec("create table country(id int, name varchar(20))"); query.exec("insert into country values(1, 'USA')"); query.exec("insert into country values(47, 'Norway')"); query.exec("insert into country values(49, 'Germany')"); } int main(int argc, char *argv[]) { QApplication app(argc, argv); if (!createConnection()) return EXIT_FAILURE; createRelationalTables(); QSqlRelationalTableModel model; initializeModel(&model); std::unique_ptr<QTableView> view = createView(QObject::tr("Relational Table Model"), &model); view->show(); return app.exec(); }
I've added some debug code into the "createView" function.
When I run the application and select, for example, the cell on the first row and the "City" column in the table, I get the following message in the console:
DisplayRole: QVariant(QString, "Oslo")
EditRole QVariant(QString, "Oslo")
Then I double-click that cell and in the combo-box, I change the city to "San Jose", for example, and again select this cell. Now I get another message in the console:
DisplayRole: QVariant(QString, "San Jose")
EditRole QVariant(qlonglong, 100).
As you can see, now the "EditRole" flag allows us to get the ID of a city in the relational table. But one cannot obtain that ID not changing the value in the cell.
How can I get that ID at once, not changing manually values in such cells? -
Hi,
You can use the model returned by QRelationalTableModel::relationModel to get the information you seek.