VDMAbstractItemModelDataType: ensure meta-type is initialized

Since the delegate chooser can call value() on a delegate model
before the first call to createItem(), we need to ensure
that all structures (and in particular, m_rolenames) are
populated also in this case.

This is especially important for cases where value() is called
for every item in the model, as is the case for e.g. auto-completion
for combo boxes, as delegate creation is particularly expensive
there.

Task-number: QTBUG-78858
Change-Id: I66138d74839b9645d11c69c29f2e70264c65a68d
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/qmlmodels/qqmladaptormodel.cpp b/src/qmlmodels/qqmladaptormodel.cpp
index 48ff4e7d5b..012540244f 100644
--- a/src/qmlmodels/qqmladaptormodel.cpp
+++ b/src/qmlmodels/qqmladaptormodel.cpp
@@ -459,6 +459,11 @@ public:
 
     QVariant value(const QQmlAdaptorModel &model, int index, const QString &role) const override
     {
+        if (!metaObject) {
+            VDMAbstractItemModelDataType *dataType = const_cast<VDMAbstractItemModelDataType *>(this);
+            dataType->initializeMetaType(model);
+        }
+
         QHash<QByteArray, int>::const_iterator it = roleNames.find(role.toUtf8());
         if (it != roleNames.end()) {
             return model.aim()->index(model.rowAt(index), model.columnAt(index), model.rootIndex).data(*it);
@@ -505,7 +510,7 @@ public:
         return new QQmlDMAbstractItemModelData(metaType, dataType, index, row, column);
     }
 
-    void initializeMetaType(QQmlAdaptorModel &model)
+    void initializeMetaType(const QQmlAdaptorModel &model)
     {
         QMetaObjectBuilder builder;
         setModelDataType<QQmlDMAbstractItemModelData>(&builder, this);