Fix mapping of JS objects/arrays to C++

[ChangeLog][QtQml][Important Behavior Changes] When a JavaScript object/array
is passed to C++ through a QVariant, the engine no longer immediately converts
the object recursively into a QVariantMap or QVariantList but instead stores
a QJSValue in the QVariant. This prevents a loss of data when the JS object
contains non-primitive types such as function objects for example. Code that
expects the variant type to be exactly QVariant::Map or QVariant::List may
need to be adapted. Registered conversion functions however ensure that code
that merely calls toMap() or toList() continues to work.

Task-number: QTBUG-40431
Change-Id: I1dbc1d5f8e78ad28bb62db3681b9a0b34557e7f5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/qml/util/qqmllistaccessor.cpp b/src/qml/util/qqmllistaccessor.cpp
index e434d6cef4..5a199abf44 100644
--- a/src/qml/util/qqmllistaccessor.cpp
+++ b/src/qml/util/qqmllistaccessor.cpp
@@ -61,6 +61,11 @@ void QQmlListAccessor::setList(const QVariant &v, QQmlEngine *engine)
 {
     d = v;
 
+    // An incoming JS array as model is treated as a variant list, so we need to
+    // convert it first with toVariant().
+    if (d.userType() == qMetaTypeId<QJSValue>())
+        d = d.value<QJSValue>().toVariant();
+
     QQmlEnginePrivate *enginePrivate = engine?QQmlEnginePrivate::get(engine):0;
 
     if (!d.isValid()) {
@@ -73,7 +78,7 @@ void QQmlListAccessor::setList(const QVariant &v, QQmlEngine *engine)
         m_type = Integer;
     } else if ((!enginePrivate && QQmlMetaType::isQObject(d.userType())) ||
                (enginePrivate && enginePrivate->isQObject(d.userType()))) {
-        QObject *data = enginePrivate?enginePrivate->toQObject(v):QQmlMetaType::toQObject(v);
+        QObject *data = enginePrivate?enginePrivate->toQObject(d):QQmlMetaType::toQObject(d);
         d = QVariant::fromValue(data);
         m_type = Instance;
     } else if (d.userType() == qMetaTypeId<QQmlListReference>()) {