title: How to return QVariant type array
body: <p>I am recently creating a model for qml with c++, but I face a problem when returning a QVariant type empty array. How should I define my return statement?</p>
  
  <pre><code>switch (role) {
  case NameRole:
      return QVariant(QStringLiteral("AAAAA"));
  case LevelRole:
      return QVariant(QStringLiteral("1"));
  case ParentRole:
      return QVariant(QStringLiteral("null"));
  case SublevelRole:
      return ???// I would like to return an empty array
  }
  </code></pre>