扩展 QStandardItem 不会返回数据

Extending QStandardItem doesnt return data

本文关键字：返回 数据 QStandardItem 扩展      更新时间：2023-10-16

我有一个自定义类ConnectionStandardItem，它是QStandardItem的一个子类。此项应包含服务器、用户名、密码等信息，以便稍后在 QSqlDatabase 中使用。

ConnectionStandardItem::ConnectionStandardItem(QString const& connectionId) : QStandardItem()
{  
QMap<QString, QVariant>  m_connectionDefinition;
QSettings settings(QSettings::IniFormat, QSettings::UserScope, "goat", "connections");
if (!connectionId.isEmpty())
{
settings.beginGroup(connectionId.trimmed());
m_connectionDefinition[connectionId] = QVariant(connectionId.trimmed());
foreach(QString key, settings.childKeys())
{
m_connectionDefinition[key] = settings.value(key);
}
setText(m_connectionDefinition["name"].toString());
setData(m_connectionDefinition, Qt::UserRole);
settings.endGroup();
}
}

扩展的QStandardItem在对话框中使用：

NewConnectionDialog::NewConnectionDialog(QWidget *parent) : QDialog(parent), ui(new Ui::NewConnectionDialog) {
ui->setupUi(this);
m_model = new QStandardItemModel(this);
m_driversModel = new QStandardItemModel(this);
m_connectionListModel = new QStandardItemModel(this);
ui->listDropdownDBDriver->setModel(m_driversModel);
ui->listViewConnections->setModel(m_connectionListModel);
/* set combobox */
QStandardItem* item_psql = new QStandardItem();
item_psql->setText("PostgreSQL");
item_psql->setData("QPSQL", Qt::UserRole);
m_driversModel->appendRow(item_psql);
QStandardItem* item_mysql = new QStandardItem();
item_mysql->setText("MySQL/MariaDB");
item_mysql->setData("QMYSQL", Qt::UserRole);
m_driversModel->appendRow(item_mysql);
updateConnectionListModel();
connect(ui->listViewConnections->selectionModel(), SIGNAL(selectionChanged(QItemSelection, QItemSelection)), this, SLOT(handleSelectionChanged(QItemSelection, QItemSelection)));
connect(m_connectionListModel, SIGNAL(itemChanged(QStandardItem*)), this, SLOT(updateListViewItem(QStandardItem*)));
}
void NewConnectionDialog::handleSelectionChanged(QItemSelection current, QItemSelection previous) {
const QModelIndex index = ui->listViewConnections->currentIndex();
ConnectionStandardItem* connection = m_connectionListModel->itemFromIndex(index)->data().value<ConnectionStandardItem*>();

QMap<QString, QVariant> connectionDefinition = connection->data().value<QMap<QString, QVariant>>();
//ui->listDropdownDBDriver->setCurrentIndex(index);
ui->txtUser->setText(connectionDefinition["username"].toString());
ui->txtPass->setText(connectionDefinition["pass"].toString());
ui->txtServer->setText(connectionDefinition["server"].toString());
ui->txtPort->setText(connectionDefinition["port"].toString());
ui->txtDatabase->setText(connectionDefinition["database"].toString());
}
void NewConnectionDialog::updateConnectionListModel() {
QSettings settings(QSettings::IniFormat, QSettings::UserScope, "goat", "connections");
foreach(QString key, settings.childGroups())
{
ConnectionStandardItem* item = new ConnectionStandardItem(key);
m_connectionListModel->appendRow(item);
}
}

不幸的是，在对话框中，我无法访问当前所选项目的数据。我正在检查的方法是句柄选择已更改。

如何从连接标准项中正确提取映射对象，以便我可以更新 GUI，反之亦然，将 gui 中的更改发送回模型(并通过模型发送到.ini设置文件(？ 有没有更好的方法来解决这个问题(组织不同的课程(？

ConnectionStandardItem 不是保存在 QStandardItem中的数据，但您必须从 QStandardItem 中转换 ConnectionStandardItem。

另一方面，将数据保存在Qt::UserRole角色中：

setData(m_connectionDefinition, Qt::UserRole);

但是，在使用data()时，您使用的是Qt::UserRole + 1角色，具体取决于文档：

QVariant QStandardItem::data(int role = Qt::UserRole + 1) const

解决方案是下一个：

void NewConnectionDialog::handleSelectionChanged(QItemSelection current, QItemSelection previous) {
const QModelIndex index = ui->listViewConnections->currentIndex();
QStandardItem *item = m_connectionListModel->itemFromIndex(index);
ConnectionStandardItem* connection  = static_cast<ConnectionStandardItem*>(item); // <---    
QMap<QString, QVariant> connectionDefinition = connection->data(Qt::UserRole).value<QMap<QString, QVariant>>(); // <---
//ui->listDropdownDBDriver->setCurrentIndex(index);
ui->txtUser->setText(connectionDefinition["username"].toString());
ui->txtPass->setText(connectionDefinition["pass"].toString());
ui->txtServer->setText(connectionDefinition["server"].toString());
ui->txtPort->setText(connectionDefinition["port"].toString());
ui->txtDatabase->setText(connectionDefinition["database"].toString());
}

虽然我看到铸造也不是必需的，因为我们不打算使用在ConnectionStandardItem中实现的方法，所以我们只能使用QStandardItem：

void NewConnectionDialog::handleSelectionChanged(QItemSelection current, QItemSelection previous) {
const QModelIndex index = ui->listViewConnections->currentIndex();
QStandardItem *connection = m_connectionListModel->itemFromIndex(index);   
QMap<QString, QVariant> connectionDefinition = connection->data(Qt::UserRole).value<QMap<QString, QVariant>>(); // <---
//ui->listDropdownDBDriver->setCurrentIndex(index);
ui->txtUser->setText(connectionDefinition["username"].toString());
ui->txtPass->setText(connectionDefinition["pass"].toString());
ui->txtServer->setText(connectionDefinition["server"].toString());
ui->txtPort->setText(connectionDefinition["port"].toString());
ui->txtDatabase->setText(connectionDefinition["database"].toString());
}
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