QSqlDriver: return the connection name of the assoicated QSqlDatabase

A QSqlDriver instance is directly bound to a QSqlDatabase object. But
there was no way to get the QSqlDatabase out of a QSqlQuery/QSqlDriver.
Fix it by storing the connection name also in the driver during
creation and add a getter for it.

[ChangeLog][QtSql][QSqlDriver] Added connectionName() which returns the
connection name of the associated QSqlDatabase instance.

Task-number: QTBUG-123603
Change-Id: If78b85413cf6ca965ff6bf9f3600cb54169b5569
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 5b07e3de3fe5335d9338c65ca40cfe656a389167)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/sql/kernel/qsqldatabase.cpp

@@ -110,8 +110,11 @@ QSqlDatabasePrivate::QSqlDatabasePrivate(const QSqlDatabasePrivate &other) : ref
     connOptions = other.connOptions;
     driver = other.driver;
     precisionPolicy = other.precisionPolicy;
-    if (driver)
+    if (driver) {
         driver->setNumericalPrecisionPolicy(other.driver->numericalPrecisionPolicy());
+        auto drvPriv = static_cast<QSqlDriverPrivate *>(QObjectPrivate::get(driver));
+        drvPriv->connectionName = connName;
+    }
 }
 
 QSqlDatabasePrivate::~QSqlDatabasePrivate()
@@ -169,6 +172,8 @@ void QSqlDatabasePrivate::addDatabase(const QSqlDatabase &db, const QString &nam
     }
     sqlGlobals->connections.insert(name, db);
     db.d->connName = name;
+    auto drvPriv = static_cast<QSqlDriverPrivate *>(QObjectPrivate::get(db.d->driver));
+    drvPriv->connectionName = name;
 }
 
 /*! \internal

src/sql/kernel/qsqldriver.cpp

@@ -801,6 +801,18 @@ int QSqlDriver::maximumIdentifierLength(QSqlDriver::IdentifierType type) const
     return INT_MAX;
 }
 
+/*!
+    \since 6.9
+
+    Returns the database connection name the driver was created by with
+    QSqlDatabase::addDatabase()
+*/
+QString QSqlDriver::connectionName() const
+{
+    Q_D(const QSqlDriver);
+    return d->connectionName;
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qsqldriver.cpp"

src/sql/kernel/qsqldriver.h

@@ -25,6 +25,7 @@ class QVariant;
 class Q_SQL_EXPORT QSqlDriver : public QObject
 {
     friend class QSqlDatabase;
+    friend class QSqlDatabasePrivate;
     friend class QSqlResultPrivate;
     Q_OBJECT
     Q_PROPERTY(QSql::NumericalPrecisionPolicy numericalPrecisionPolicy READ numericalPrecisionPolicy WRITE setNumericalPrecisionPolicy)
@@ -98,6 +99,9 @@ public:
 
     DbmsType dbmsType() const;
     virtual int maximumIdentifierLength(IdentifierType type) const;
+
+    QString connectionName() const;
+
 public Q_SLOTS:
     virtual bool cancelQuery();
 

src/sql/kernel/qsqldriver_p.h

@@ -32,6 +32,7 @@ public:
         dbmsType(type)
     { }
 
+    QString connectionName;
     QSqlError error;
     QSql::NumericalPrecisionPolicy precisionPolicy = QSql::LowPrecisionDouble;
     QSqlDriver::DbmsType dbmsType;