1 files changed, 44 insertions, 18 deletions
diff --git a/src/qmlmodels/qqmldelegatemodel.cpp b/src/qmlmodels/qqmldelegatemodel.cpp
index ec75a5775c..13965d316b 100644
--- a/src/qmlmodels/qqmldelegatemodel.cpp
+++ b/src/qmlmodels/qqmldelegatemodel.cpp
@@ -167,6 +167,7 @@ QQmlDelegateModelPrivate::QQmlDelegateModelPrivate(QQmlContext *ctxt)
     , m_transaction(false)
     , m_incubatorCleanupScheduled(false)
     , m_waitingToFetchMore(false)
+    , m_maybeResetRoleNames(false)
     , m_cacheItems(nullptr)
     , m_items(nullptr)
     , m_persistedItems(nullptr)
@@ -371,6 +372,8 @@ void QQmlDelegateModelPrivate::connectToAbstractItemModel()
     QObject::connect(aim, &QAbstractItemModel::modelAboutToBeReset, q, &QQmlDelegateModel::_q_modelAboutToBeReset);
     qmlobject_connect(aim, QAbstractItemModel, SIGNAL(layoutChanged(QList<QPersistentModelIndex>,QAbstractItemModel::LayoutChangeHint)),
                       q, QQmlDelegateModel, SLOT(_q_layoutChanged(QList<QPersistentModelIndex>,QAbstractItemModel::LayoutChangeHint)));
+    QObject::connect(aim, &QAbstractItemModel::modelReset, q, &QQmlDelegateModel::handleModelReset);
+    QObject::connect(aim, &QAbstractItemModel::layoutChanged, q, &QQmlDelegateModel::_q_layoutChanged);
 }
 
 void QQmlDelegateModelPrivate::disconnectFromAbstractItemModel()
@@ -400,6 +403,8 @@ void QQmlDelegateModelPrivate::disconnectFromAbstractItemModel()
     QObject::disconnect(aim, &QAbstractItemModel::modelAboutToBeReset, q, &QQmlDelegateModel::_q_modelAboutToBeReset);
     QObject::disconnect(aim, SIGNAL(layoutChanged(QList<QPersistentModelIndex>,QAbstractItemModel::LayoutChangeHint)),
                         q, SLOT(_q_layoutChanged(QList<QPersistentModelIndex>,QAbstractItemModel::LayoutChangeHint)));
+    QObject::disconnect(aim, &QAbstractItemModel::modelReset, q, &QQmlDelegateModel::handleModelReset);
+    QObject::disconnect(aim, &QAbstractItemModel::layoutChanged, q, &QQmlDelegateModel::_q_layoutChanged);
 }
 
 void QQmlDelegateModel::setModel(const QVariant &model)
@@ -1851,24 +1856,28 @@ void QQmlDelegateModelPrivate::emitChanges()
 
 void QQmlDelegateModel::_q_modelAboutToBeReset()
 {
-    auto aim = static_cast<QAbstractItemModel *>(sender());
-    auto oldRoleNames = aim->roleNames();
-    // this relies on the fact that modelAboutToBeReset must be followed
-    // by a modelReset signal before any further modelAboutToBeReset can occur
-    QObject::connect(aim, &QAbstractItemModel::modelReset, this, [&, oldRoleNames](){
-        auto aim = static_cast<QAbstractItemModel *>(sender());
-        if (oldRoleNames == aim->roleNames()) {
-            // if the rolenames stayed the same (most common case), then we don't have
-            // to throw away all the setup that we did
-            handleModelReset();
-        } else {
-            // If they did change, we give up and just start from scratch via setMode
-            setModel(QVariant::fromValue(model()));
-            // but we still have to call handleModelReset, otherwise views will
-            // not refresh
-            handleModelReset();
-        }
-    }, Qt::SingleShotConnection);
+    /*
+        roleNames are generally guaranteed to be stable (given that QAIM has no
+        change signal for them), except that resetting the model is allowed to
+        invalidate them (QTBUG-32132). DelegateModel must take this into account by
+        snapshotting the current roleNames before the model is reset.
+        Afterwards, if we detect that roleNames has changed, we throw the
+        current model set up away and rebuild everything from scratch – it is
+        unlikely that a more efficient implementation would be worth it.
+
+        If we detect no changes, we simply use the existing logic to handle the
+        model reset.
+
+        This (role name resetting) logic relies on the fact that
+        modelAboutToBeReset must be followed by a modelReset signal before any
+        further modelAboutToBeReset can occur. However, it's possible for user
+        code to begin the reset before connectToAbstractItemModel is called
+        (QTBUG-125053), in which case we don't attempt to reset the role names.
+    */
+    Q_D(QQmlDelegateModel);
+    Q_ASSERT(!d->m_maybeResetRoleNames);
+    d->m_maybeResetRoleNames = true;
+    d->m_roleNamesBeforeReset = d->m_adaptorModel.aim()->roleNames();
 }
 
 void QQmlDelegateModel::handleModelReset()
@@ -1878,6 +1887,23 @@ void QQmlDelegateModel::handleModelReset()
         return;
 
     int oldCount = d->m_count;
+
+    if (d->m_maybeResetRoleNames) {
+        auto aim = d->m_adaptorModel.aim();
+        if (!d->m_adaptorModel.adaptsAim() || d->m_adaptorModel.aim() != aim)
+            return;
+
+        // If the role names stayed the same (most common case), then we don't have
+        // to throw away all the setup that we did.
+        // If they did change, we give up and just start from scratch via setModel.
+        // We do this before handling the reset to ensure that views refresh.
+        if (aim->roleNames() != d->m_roleNamesBeforeReset)
+            setModel(QVariant::fromValue(model()));
+
+        d->m_maybeResetRoleNames = false;
+        d->m_roleNamesBeforeReset.clear();
+    }
+
     d->m_adaptorModel.rootIndex = QModelIndex();
 
     if (d->m_complete) {