为 QML 树视图创建模型

我正在尝试使用QML树视图模型。Qt的例子不包括如何创建模型。我阅读了这篇文章并尝试使用@Tarod的代码，但结果不是我预期的。

主.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "animalmodel.h"
#include <qqmlcontext.h>
#include <qqml.h>
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
AnimalModel model;
model.addAnimal("wolf", "Medium");
model.addAnimal("Bear", "Large");
QQmlApplicationEngine engine;
QQmlContext *ctxt = engine.rootContext();
ctxt->setContextProperty("myModel", &model);
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
if (engine.rootObjects().isEmpty())
return -1;
return app.exec();
}

动物模型.h

#ifndef ANIMALMODEL_H
#define ANIMALMODEL_H
#include <QStandardItemModel>

class AnimalModel : public QStandardItemModel
{
Q_OBJECT //The Q_OBJECT macro must appear in the private section of a class definition that declares its own signals and slots or that uses other services provided by Qt's meta-object system.
public:
enum AnimalRoles {
TypeRole = Qt::UserRole + 1,
SizeRole
};
AnimalModel(QObject *parent = 0);
Q_INVOKABLE void addAnimal(const QString &type, const QString &size);
QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
protected:
QHash<int, QByteArray> roleNames() const;
};
#endif // ANIMALMODEL_H

动物模型.cpp

#include "animalmodel.h"
AnimalModel::AnimalModel(QObject *parent)
: QStandardItemModel(parent)
{
}
void AnimalModel::addAnimal(const QString &type, const QString &size)
{
QStandardItem* entry = new QStandardItem();
entry->setData(type, TypeRole);
auto childEntry = new QStandardItem();
childEntry->setData(size, SizeRole);
entry->appendRow(childEntry);
appendRow(entry);
}
QVariant AnimalModel::data(const QModelIndex & index, int role) const {
QStandardItem *myItem = itemFromIndex(index);
if (role == TypeRole)
return myItem->data(TypeRole);
else if (role == SizeRole) {
if (myItem->child(0) != 0)
{
return myItem->child(0)->data(SizeRole);
}
}
return QVariant();
}
QHash<int, QByteArray> AnimalModel::roleNames() const {
QHash<int, QByteArray> roles;
roles[TypeRole] = "type";
roles[SizeRole] = "size";
return roles;
}

主.qml

import QtQuick 2.6
import QtQuick.Window 2.2
import QtQuick.Controls 1.4

ApplicationWindow {
visible: true
width: 640
height: 480
title: qsTr("Hello World")
menuBar: MenuBar {
Menu {
title: qsTr("&File")
MenuItem {
text: qsTr("&Open")
onTriggered: messageDialog.show(qsTr("Open Action Triggered"));
}
MenuItem {
text: qsTr("&Exit")
onTriggered: Qt.quit();
}
}
}

TreeView {
anchors.fill: parent
model: myModel
TableViewColumn {
title: "Name"
role: "type"
width: 300
}
TableViewColumn {
title: "Size"
role: "size"
width: 300
}
}
}

我得到的是这样的： 结果

我想要的是作为动物类型孩子的动物大小。