Support required properties in model delegates

If a delegates declares a required property of a given name, and that
name exists as a role in the model, we set the property accordingly.
The same holds true for the special properties that come from the
QQmlDelegateModel like "index" and "model".

All roles are still injected into scope and thus accessible;
changing this in Qt5 would be tedious or even impossible while still
maintaining backwardscompatibility with delegates that do not use
required properties.

Change-Id: I4f388ba549c42f1ff9822bdb3b8357c4d45e4b66
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 86 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
index 7c26c22217..bf593cfd2e 100644
--- a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
+++ b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
@@ -280,6 +280,8 @@ private slots:
     void touchCancel();
     void resizeAfterComponentComplete();
 
+    void delegateWithRequiredProperties();
+
 private:
     template <class T> void items(const QUrl &source);
     template <class T> void changed(const QUrl &source);
@@ -9037,6 +9039,90 @@ void tst_QQuickListView::resizeAfterComponentComplete()  // QTBUG-76487
     QTRY_COMPARE(lastItem->property("y").toInt(), 9 * lastItem->property("height").toInt());
 }
 
+class Animal
+{
+public:
+    Animal(const int cost, const QString &name) {m_name = name; m_cost = cost;}
+
+    int cost() const {return m_cost;}
+    QString name() const {return m_name;}
+
+    QString m_name;
+    int m_cost;
+};
+
+class FruitModel : public QAbstractListModel
+{
+    Q_OBJECT
+public:
+    enum AnimalRoles {
+        NameRole = Qt::UserRole + 1,
+        CostRole
+    };
+
+    FruitModel(QObject* = nullptr) {
+        m_animals.push_back(Animal {4, QLatin1String("Melon")});
+        m_animals.push_back(Animal {5, QLatin1String("Cherry")});
+    }
+
+    int rowCount(const QModelIndex & = QModelIndex()) const override {return m_animals.count();}
+
+    QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const override {
+        if (!checkIndex(index))
+            return {};
+        const Animal &animal = m_animals[index.row()];
+        if (role == CostRole)
+            return animal.cost();
+        else if (role == NameRole)
+            return animal.name();
+        return QVariant();
+    }
+
+protected:
+    QHash<int, QByteArray> roleNames() const override {
+        QHash<int, QByteArray> roles;
+        roles[CostRole] = "cost";
+        roles[NameRole] = "name";
+        return roles;
+    }
+private:
+    QList<Animal> m_animals;
+};
+
+void tst_QQuickListView::delegateWithRequiredProperties()
+{
+    FruitModel myModel;
+    qmlRegisterSingletonInstance("Qt.fruit", 1, 0, "FruitModelCpp", &myModel);
+    {
+        // ListModel
+        QTest::ignoreMessage(QtMsgType::QtDebugMsg, "Apple2");
+        QTest::ignoreMessage(QtMsgType::QtDebugMsg, "Orange3");
+        QTest::ignoreMessage(QtMsgType::QtDebugMsg, "Banana1");
+        QScopedPointer<QQuickView> window(createView());
+        window->setInitialProperties({{QLatin1String("useCpp"), false}});
+        window->setSource(testFileUrl("delegatesWithRequiredProperties.qml"));
+        window->show();
+        QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+
+        QObject *listView = window->rootObject();
+        QVERIFY(listView);
+    }
+    {
+        // C++ model
+        QTest::ignoreMessage(QtMsgType::QtDebugMsg, "Melon4");
+        QTest::ignoreMessage(QtMsgType::QtDebugMsg, "Cherry5");
+        QScopedPointer<QQuickView> window(createView());
+        window->setInitialProperties({{QLatin1String("useCpp"), true}});
+        window->setSource(testFileUrl("delegatesWithRequiredProperties.qml"));
+
+        window->show();
+        QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+
+        QObject *listView = window->rootObject();
+        QVERIFY(listView);
+    }
+}
+
 QTEST_MAIN(tst_QQuickListView)
 
 #include "tst_qquicklistview.moc"