Qt6中QTreeWidget控件,显示树形数据(Sqlite)的方法

数据源和显示效果

 

思路

自定义一个容器:

QHash *map = new QHash;

key是节点的id

value是节点本身

先从数据库中按pid升序查询,遍历他.

如果pid为0,设置他的父节点为ui->treeWidget,后存入QHash容器

如果是其他,暂时不设置父节点,后存入QHash容器

数据库指针回到第一个,再遍历一次.

如果pid为0,不做处理.

使用id在QHash容器中返回节点本身.

使用pid在QHash容器中返回父节点.

父节点添加当前节点为子节点即可.

代码

#include "dialog.h"
#include 
#include "ui_dialog.h"

Dialog::Dialog(QWidget *parent)
    : QDialog(parent)
    , ui(new Ui::Dialog)
{
    ui->setupUi(this);
    QDateTime startTime = QDateTime::currentDateTime(); //开始计时
    ui->treeWidget->setHeaderLabel("单位全称");

    this->db = QSqlDatabase::addDatabase("QSQLITE");
    this->db.setDatabaseName("data.db");
    if (!db.open()) {
        // 连接失败的处理逻辑
        qDebug() << "连接失败";
        return;
    }
    QSqlQuery query;
    int id;
    int pid;
    QString name;
    QHash *map = new QHash;

    query.exec("SELECT * FROM dw_name ORDER BY pid;");
    while (query.next()) {
        id = query.value("id").toInt();
        pid = query.value("pid").toInt();
        name = query.value("name").toString();
        if (pid == 0) {
            QTreeWidgetItem *item = new QTreeWidgetItem(ui->treeWidget, QStringList() << name);
            map->insert(id, item);
        } else {
            QTreeWidgetItem *item = new QTreeWidgetItem(QStringList() << name);
            map->insert(id, item);
        }
    }
    query.first();
    while (query.next()) {
        id = query.value("id").toInt();
        pid = query.value("pid").toInt();
        name = query.value("name").toString();
        if (pid == 0) {
        } else {
            QTreeWidgetItem *child_item = map->value(id);
            QTreeWidgetItem *p_item = map->value(pid);
            p_item->addChild(child_item);
        }
    }

    QDateTime endTime = QDateTime::currentDateTime(); //结束计时
    qint64 elapsedMilliseconds = endTime.toMSecsSinceEpoch() - startTime.toMSecsSinceEpoch();
    QTime elapsedTime = QTime(0, 0, 0, elapsedMilliseconds);

    qDebug() << "Elapsed time:" << elapsedTime.toString("mm:ss.zzz");
    ui->treeWidget->expandAll();
}

Dialog::~Dialog()
{
    delete ui;
}

注意事项

数据库中按pid升序查询,一定要注意,一些节点因为pid数值大,可能会排在后面,所以这里一定不能按pid升序查询的结果,同时设置顶层节点和二层以下的父节点.