Allow adding null to QQmlListProperty

Setting the length or deleting objects already produces nullptr entries.
It should be possible to add them explicitly.

Also, fix the documentation to mention that you can actually manipulate
list properties, and do not recommend 'var' as replacement.

Change-Id: Ib04356f086b026191e60b6423f6ed44c2870235f
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 15 insertions, 4 deletions

diff --git a/src/qml/qml/qqmllistwrapper.cpp b/src/qml/qml/qqmllistwrapper.cpp
index e3ab0082aa..d8bf3c9704 100644
--- a/src/qml/qml/qqmllistwrapper.cpp
+++ b/src/qml/qml/qqmllistwrapper.cpp
@@ -156,6 +156,11 @@ bool QmlListWrapper::virtualPut(Managed *m, PropertyKey id, const Value &value,
         if (count < 0 || index >= uint(count))
             return false;
 
+        if (value.isNull()) {
+            prop->replace(prop, index, nullptr);
+            return true;
+        }
+
         QV4::Scope scope(v4);
         QV4::ScopedObject so(scope, value.toObject(scope.engine));
         if (auto *wrapper = so->as<QV4::QObjectWrapper>()) {
@@ -251,15 +256,21 @@ ReturnedValue PropertyListPrototype::method_push(const FunctionObject *b, const
     QmlListWrapper *w = instance->as<QmlListWrapper>();
     if (!w)
         RETURN_UNDEFINED();
-    if (!w->d()->property().append)
+
+    QQmlListProperty<QObject> *property = &w->d()->property();
+    if (!property->append)
         THROW_GENERIC_ERROR("List doesn't define an Append function");
 
     QV4::ScopedObject so(scope);
     for (int i = 0, ei = argc; i < ei; ++i)
     {
-        so = argv[i].toObject(scope.engine);
-        if (QV4::QObjectWrapper *wrapper = so->as<QV4::QObjectWrapper>())
-            w->d()->property().append(&w->d()->property(), wrapper->object() );
+        if (argv[i].isNull()) {
+            property->append(property, nullptr);
+        } else {
+            so = argv[i].toObject(scope.engine);
+            if (QV4::QObjectWrapper *wrapper = so->as<QV4::QObjectWrapper>())
+                property->append(property, wrapper->object() );
+        }
     }
     return Encode::undefined();
 }