Doc: some ComboBox functions must be used after component completion

The internal QQmlDelegate model may not be ready until after
componentComplete() is called. For example, the following code will
print -1 for the find call, even though printing the model will
show the "Hello" entry:

    ComboBox {
        id: comboBug
        anchors.centerIn: parent
        model: ["123", "BlaBla", "Hello", "Turtle"]
        currentIndex: {
            console.log("Model: " + comboBug.model)
            console.log("Find:  " + comboBug.find("Hello"))
            return comboBug.find("Hello")
        }
    }

Fixes: QTBUG-94257
Pick-to: 6.1 6.2
Change-Id: I6e8c2a4eb8ca7ffca0a38d2f2e914cf791d3bd2e
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

1 files changed, 40 insertions, 0 deletions

diff --git a/src/quickcontrols2/doc/snippets/qtquickcontrols2-combobox-find.qml b/src/quickcontrols2/doc/snippets/qtquickcontrols2-combobox-find.qml
new file mode 100644
index 00000000..c14ebbbe
--- /dev/null
+++ b/src/quickcontrols2/doc/snippets/qtquickcontrols2-combobox-find.qml
@@ -0,0 +1,40 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick
+import QtQuick.Controls
+
+//! [find]
+ComboBox {
+    model: ListModel {
+        ListElement { text: "Banana" }
+        ListElement { text: "Apple" }
+        ListElement { text: "Coconut" }
+    }
+    Component.onCompleted: currentIndex = find("Coconut")
+}
+//! [find]