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, 11 insertions, 0 deletions

diff --git a/src/qml/types/qqmllistmodel.cpp b/src/qml/types/qqmllistmodel.cpp
index 25879972ca..142625d7ae 100644
--- a/src/qml/types/qqmllistmodel.cpp
+++ b/src/qml/types/qqmllistmodel.cpp
@@ -1330,6 +1330,11 @@ void DynamicRoleModelNode::updateValues(const QVariantMap &object, QVector<int>
 
         QVariant value = object[key];
 
+        // A JS array/object is translated into a (hierarchical) QQmlListModel,
+        // so translate to a variant map/list first with toVariant().
+        if (value.userType() == qMetaTypeId<QJSValue>())
+            value = value.value<QJSValue>().toVariant();
+
         if (value.type() == QVariant::List) {
             QQmlListModel *subModel = QQmlListModel::createWithOwner(m_owner);
 
@@ -1392,6 +1397,12 @@ void DynamicRoleModelNodeMetaObject::propertyWritten(int index)
     QQmlListModel *parentModel = m_owner->m_owner;
 
     QVariant v = value(index);
+
+    // A JS array/object is translated into a (hierarchical) QQmlListModel,
+    // so translate to a variant map/list first with toVariant().
+    if (v.userType() == qMetaTypeId<QJSValue>())
+        v= v.value<QJSValue>().toVariant();
+
     if (v.type() == QVariant::List) {
         QQmlListModel *subModel = QQmlListModel::createWithOwner(parentModel);