在postgresql中生成自动ID(Generate auto ID in postgresql)

 您的示例应该稍微调整一下以使用QFileSystemModel 。 
 
 诀窍是声明checkedIndexes设置为mutable并在CFileSystemModel::data方法中更新它。 
 
QVariant CFileSystemModel::data(const QModelIndex &index, int role) const
{
    if(role == Qt::CheckStateRole)
    {
        if (checkedIndexes.contains(index))
        {
            return checkedIndexes.contains(index) ? Qt::Checked : Qt::Unchecked;
        }
        else
        {
            int checked = Qt::Unchecked;

            QModelIndex parent = index.parent();
            while (parent.isValid())
            {
                if (checkedIndexes.contains(parent))
                {
                    checked = Qt::Checked;
                    break;
                }

                parent = parent.parent();
            }

            if (checked == Qt::Checked)
            {
                checkedIndexes.insert(parent);
            }

            return checked;
        }
    }
    else
    {
        return QFileSystemModel::data(index, role);
    }
}
 
 在视图中打开目录节点时， QFileSystemModel开始加载新内容。 加载后，视图使用CFileSystemModel::data函数重新获取新数据，该函数检查是否检查了新节点的anchestors并返回正确的Qt::CheckStateRole值（并且还更新了checkedIndexes集）。 

Your example should be tweaked a bit to use QFileSystemModel.
 
The trick is to declare the checkedIndexes set as mutable and update it inside the CFileSystemModel::data method.
 
QVariant CFileSystemModel::data(const QModelIndex &index, int role) const
{
    if(role == Qt::CheckStateRole)
    {
        if (checkedIndexes.contains(index))
        {
            return checkedIndexes.contains(index) ? Qt::Checked : Qt::Unchecked;
        }
        else
        {
            int checked = Qt::Unchecked;

            QModelIndex parent = index.parent();
            while (parent.isValid())
            {
                if (checkedIndexes.contains(parent))
                {
                    checked = Qt::Checked;
                    break;
                }

                parent = parent.parent();
            }

            if (checked == Qt::Checked)
            {
                checkedIndexes.insert(parent);
            }

            return checked;
        }
    }
    else
    {
        return QFileSystemModel::data(index, role);
    }
}
 
When you open a directory node in a view, QFileSystemModel starts to load new contents. After they are loaded, the view retieves new data using CFileSystemModel::data function, which checks if new nodes anchestors were checked and returns proper Qt::CheckStateRole value (and also updates the checkedIndexes set).