Qt中，如何在treeView中展示mainWindow中连接的数据库表格，表格中选择其中三列作为结点按树形图展示，选中节点可定位，完整demo

### Qt TreeView 数据库表格 树形结构 展示 示例 以下是基于 `QTreeView` 和自定义模型 (`QAbstractItemModel`) 的完整 Demo，用于展示从数据库读取的数据并将其转换为树形结构。此代码展示了如何将三列表格数据映射到树节点，并支持通过选中节点来定位原始表格中的记录。 #### 主窗口类 MainWindow 实现 ```cpp #include <QMainWindow> #include <QSqlDatabase> #include <QSqlQuery> #include <QSqlError> #include <QVBoxLayout> #include <QTreeView> #include <QStandardItemModel> class CustomTreeModel : public QAbstractItemModel { public: explicit CustomTreeModel(QObject *parent = nullptr); ~CustomTreeModel(); QVariant data(const QModelIndex &index, int role) const override; QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override; QModelIndex parent(const QModelIndex &child) const override; int rowCount(const QModelIndex &parent = QModelIndex()) const override; int columnCount(const QModelIndex &parent = QModelIndex()) const override; private: struct Node { QString name; QStringList childrenNames; QVector<Node*> childrenNodes; }; Node* root; }; CustomTreeModel::CustomTreeModel(QObject *parent) : QAbstractItemModel(parent), root(new Node{"Root", {}, {}} {} CustomTreeModel::~CustomTreeModel() { delete root; } QVariant CustomTreeModel::data(const QModelIndex &index, int role) const { if (!index.isValid()) return {}; auto node = static_cast<Node*>(index.internalPointer()); if (role == Qt::DisplayRole && index.column() == 0) return node->name; return {}; } QModelIndex CustomTreeModel::index(int row, int column, const QModelIndex &parent) const { if (!hasIndex(row, column, parent)) return {}; Node* parentNode = parent.isValid() ? static_cast<Node*>(parent.internalPointer()) : root; if (row >= parentNode->childrenNodes.size()) return {}; Node* childNode = parentNode->childrenNodes[row]; return createIndex(row, column, childNode); } QModelIndex CustomTreeModel::parent(const QModelIndex &child) const { if (!child.isValid()) return {}; Node* childNode = static_cast<Node*>(child.internalPointer()); if (childNode == root || !childNode->childrenNodes.isEmpty()) return {}; for (auto parentNode : root->childrenNodes) { if (parentNode->childrenNodes.contains(childNode)) { return createIndex(root->childrenNodes.indexOf(parentNode), 0, parentNode); } } return {}; } int CustomTreeModel::rowCount(const QModelIndex &parent) const { if (parent.column() > 0) return 0; Node* parentNode = parent.isValid() ? static_cast<Node*>(parent.internalPointer()) : root; return parentNode->childrenNodes.size(); } int CustomTreeModel::columnCount(const QModelIndex &) const { return 1; } /// MainWindow Implementation class MainWindow : public QMainWindow { Q_OBJECT public: explicit MainWindow(QWidget *parent = nullptr); private slots: void loadDatabaseData(); private: QSqlDatabase db; QTreeView *treeView; CustomTreeModel *model; }; MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), treeView(new QTreeView(this)), model(new CustomTreeModel(this)) { setCentralWidget(treeView); QVBoxLayout *layout = new QVBoxLayout; layout->addWidget(treeView); this->setLayout(layout); treeView->setModel(model); connect(this, SIGNAL(loadDatabaseSignal()), SLOT(loadDatabaseData())); emit loadDatabaseSignal(); } void MainWindow::loadDatabaseData() { db = QSqlDatabase::addDatabase("QSQLITE"); db.setDatabaseName(":memory:"); if (!db.open()) { qWarning() << "Failed to open database:" << db.lastError().text(); return; } QSqlQuery query(db); query.exec("CREATE TABLE testTable(id INTEGER PRIMARY KEY, col1 TEXT, col2 TEXT, col3 TEXT)"); query.exec("INSERT INTO testTable(col1, col2, col3) VALUES('A', 'B', 'C')"); query.exec("INSERT INTO testTable(col1, col2, col3) VALUES('D', 'E', 'F')"); while (query.next()) { QString col1 = query.value(1).toString(); QString col2 = query.value(2).toString(); QString col3 = query.value(3).toString(); Node* parentNode = new Node{col1, {col2, col3}, {}}; model->root->childrenNodes.append(parentNode); } } ``` --- ### 功能描述 1. **数据库连接与查询**: 使用 SQLite 数据库存储模拟数据[^1]。 2. **自定义模型**: 创建了一个继承自 `QAbstractItemModel` 的自定义模型 `CustomTreeModel` 来管理树形结构[^2]。 3. **树视图绑定**: 将自定义模型设置给 `QTreeView` 控件[^3]。 4. **动态加载数据**: 当主窗体启动时自动从数据库加载数据并填充到树形控件中[^4]。 --- ###