QQuickTableView: sync model and delegate when ready to do so

Doing (silly) things in the delegate, like:

    Component.onCompleted: TableView.view.delegate = null

will lead to a crash. The same if you change the model.
The reason is that you end up changing the model
while e.g a row is half-way loaded. Information needed for
building the row, like model size, will then be invalid.

To protect against this, we insert a "sync" phase to the
code that takes any such changes into effect at a time
when we know it's safe to do so.

Change-Id: I85a992dfc0e04ec6635b10c9768a8ddc140e09da
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 47 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp b/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp
index 9eb942fc93..a1951bdf90 100644
--- a/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp
+++ b/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp
@@ -106,6 +106,8 @@ private slots:
     void checkExplicitContentWidthAndHeight();
     void checkContentXY();
     void noDelegate();
+    void changeDelegateDuringUpdate();
+    void changeModelDuringUpdate();
     void countDelegateItems_data();
     void countDelegateItems();
     void checkLayoutOfEqualSizedDelegateItems_data();
@@ -664,6 +666,51 @@ void tst_QQuickTableView::noDelegate()
     QVERIFY(items.isEmpty());
 }
 
+void tst_QQuickTableView::changeDelegateDuringUpdate()
+{
+    // Check that you can change the delegate (set it to null)
+    // while the TableView is busy loading the table.
+    LOAD_TABLEVIEW("changemodelordelegateduringupdate.qml");
+
+    auto model = TestModelAsVariant(1, 1);
+    tableView->setModel(model);
+    view->rootObject()->setProperty("changeDelegate", true);
+
+    WAIT_UNTIL_POLISHED;
+
+    // We should no longer have a delegate, and no
+    // items should therefore be loaded.
+    QCOMPARE(tableView->delegate(), nullptr);
+    QCOMPARE(tableViewPrivate->loadedItems.size(), 0);
+
+    // Even if the delegate is missing, we still report
+    // the correct size of the model
+    QCOMPARE(tableView->rows(), 1);
+    QCOMPARE(tableView->columns(), 1);
+};
+
+void tst_QQuickTableView::changeModelDuringUpdate()
+{
+    // Check that you can change the model (set it to null)
+    // while the TableView is buzy loading the table.
+    LOAD_TABLEVIEW("changemodelordelegateduringupdate.qml");
+
+    auto model = TestModelAsVariant(1, 1);
+    tableView->setModel(model);
+    view->rootObject()->setProperty("changeModel", true);
+
+    WAIT_UNTIL_POLISHED;
+
+    // We should no longer have a model, and the no
+    // items should therefore be loaded.
+    QVERIFY(tableView->model().isNull());
+    QCOMPARE(tableViewPrivate->loadedItems.size(), 0);
+
+    // The empty model has no rows or columns
+    QCOMPARE(tableView->rows(), 0);
+    QCOMPARE(tableView->columns(), 0);
+};
+
 void tst_QQuickTableView::countDelegateItems_data()
 {
     QTest::addColumn<QVariant>("model");