代码改错只显示修改部分：现在提示QMetaObjectconnectSlotsByName No matching signal for on_modeComboBox_currentIndexChangedint该如何修改#ifndef USERSWIDGET_H#define USERSWIDGET_H#include QWidgetnamespace Ui class UsersWidget

代码修改如下：

userswidget.h:

#ifndef USERSWIDGET_H
#define USERSWIDGET_H

#include <QWidget>

namespace Ui {
class UsersWidget;
}

class UsersWidget : public QWidget
{
    Q_OBJECT

public:
    explicit UsersWidget(int userid, QWidget *parent = nullptr);
    ~UsersWidget();
    void displayUsersWidget();

protected:
    void closeEvent(QCloseEvent *);

signals:
    void modeChanged(int mode); // 修改信号参数类型为int

private slots:
    void on_modeComboBox_currentIndexChanged(int index);

private:
    Ui::UsersWidget *ui;
    int userid;
};

#endif // USERSWIDGET_H

userswidget.cpp:

#include "userswidget.h"
#include "ui_userswidget.h"
#include "sqlite.h"
#include "lights.h"
#include "aircondition.h"
#include "curtains.h"
#include "humidiffer.h"
#include "information.h"
#include "procession.h"
#include <QCloseEvent>
#include <QMessageBox>

UsersWidget::UsersWidget(int userid, QWidget *parent) :
    QWidget(parent),
    ui(new Ui::UsersWidget),
    userid(userid) // 初始化成员变量userid
{
    ui->setupUi(this);
    displayUsersWidget();
    connect(ui->lights,&QToolButton::clicked,this,[=]{
        Lights *w = new Lights(userid);
        w->show();});
    connect(ui->air_condition,&QToolButton::clicked,this,[=]{
        AirCondition *w = new AirCondition(userid);
        w->show();});
    connect(ui->curtains,&QToolButton::clicked,this,[=]{
        Curtains *w = new Curtains(userid);
        w->show();});
    connect(ui->humidifiers,&QToolButton::clicked,this,[=]{
        Humidiffer *w = new Humidiffer(userid);
        w->show();});
    connect(ui->tables,&QToolButton::clicked,this,[=]{
        Information *w = new Information;
        w->show();});
    connect(ui->wifi,&QToolButton::clicked,this,[=]{
        Procession *w = new Procession;
        w->show();});
    connect(ui->mode, QOverload<int>::of(&QComboBox::currentIndexChanged),
            this, &UsersWidget::on_modeComboBox_currentIndexChanged);

    // 连接modeChanged信号与on_modeComboBox_currentIndexChanged槽函数
    connect(this, &UsersWidget::modeChanged, this, &UsersWidget::on_modeComboBox_currentIndexChanged);
}

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

void UsersWidget::displayUsersWidget()
{
    setWindowTitle("智能家居总览图");
    setFixedSize(900,600);

}

void UsersWidget::on_modeComboBox_currentIndexChanged(int mode)
{
    switch (mode)
    {
        case 1:
        {
        updateSmartHomeStatus(userid, "智能灯", "开启", "20");
        updateSmartHomeStatus(userid, "空调", "开启", "27");
        updateSmartHomeStatus(userid, "加湿器", "开启", "50");
        updateSmartHomeStatus(userid, "窗帘", "开启", "100");
        break;
        }
        case 2:
        {
        updateSmartHomeStatus(userid, "智能灯", "开启", "20");
        updateSmartHomeStatus(userid, "空调", "开启", "27");
        updateSmartHomeStatus(userid, "加湿器", "开启", "50");
        updateSmartHomeStatus(userid, "窗帘", "开启", "100");
        break;
        }
        case 3:
        {
        updateSmartHomeStatus(userid, "智能灯", "开启", "50");
        updateSmartHomeStatus(userid, "空调", "开启", "26");
        updateSmartHomeStatus(userid, "加湿器", "开启", "40");
        updateSmartHomeStatus(userid, "窗帘", "开启", "30");
        break;
        }
        default:;
    }
}

void UsersWidget::closeEvent(QCloseEvent *e)
{
    if(e->spontaneous())
    {
        //窗口关闭时弹出的提示窗口
        QMessageBox::StandardButton reply;
        reply = QMessageBox::information(this,"提示","确认退出智能管家系统？",QMessageBox::Yes|QMessageBox::No);
        if(reply == QMessageBox::Yes){
            //若用户点击确认，则接收这个事件,当前窗口会关闭
            e->accept();
         }else{
            //若用户点击取消，则忽略这个事件，当前窗口不会关闭
            e->ignore();
        }
    }
}

sqlite.cpp:

#include <QSqlDatabase>
#include <QSqlQuery>
#include <QMessageBox>
#include <QDebug>
#include <QSqlError>
#include "sqlite.h"

Sqlite::Sqlite()
{

}

void Sqlite::sqlite_init()
{
    // 先关闭重复的数据库连接
    if (QSqlDatabase::contains("qt_sql_default_connection")) {
        QSqlDatabase::removeDatabase("qt_sql_default_connection");
    }
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("../Smarthome_Client/database/database.db");
    if(!db.open())
    {
        qDebug()<<"无法打开数据库！";
    }
    else{
        qDebug()<<"数据库打开成功！";
    }
}

void updateSmartHomeStatus(int userId, QString deviceName, QString devicestate, QString newValue)
{
    Sqlite::sqlite_init();
    // 执行更新操作
    QSqlQuery query;
    query.prepare("SELECT * FROM Status WHERE uid = :userId");
    query.bindValue(":userId", userId);
    if (!query.exec()) {
        qDebug() << "查询id失败：" << query.lastError().text();
    } else {
        QString sql = QString("INSERT INTO Status (uid, device_name, device_state, value) VALUES (%1, '%2', '%3', '%4')")
                .arg(userId).arg(deviceName).arg(devicestate).arg(newValue);
        query.prepare(sql);
        if (!query.exec()) {
            qDebug() << "插入数据失败：" << query.lastError().text();
            return;
        }
    }
}

bool statusUid(int userId)
{
    Sqlite::sqlite_init();
    QSqlQuery query;
    // 查询智能家居状态表，获取用户对应的状态
    query.prepare("SELECT * FROM status WHERE uid = :userId");
    query.bindValue(":userId", userId);
    qDebug()<<query.exec();
    if (!query.next()) {
        qDebug() << "Failed to execute query!"<<query.lastError().text();
        return false;
    } else {
        qDebug() << "Successed to execute query!";
        return true;
    }
}

数据库脚本:

-- 创建智能家居状态表
CREATE TABLE IF NOT EXISTS Status (
    sid INTEGER PRIMARY KEY AUTOINCREMENT,
    uid INTEGER ,
    device_name varchar(10),
    device_state varchar(10),
    value varchar(10),
    mode varchar(10),
    FOREIGN KEY (uid) REFERENCES users (uid)
);

-- 创建用户表
CREATE TABLE IF NOT EXISTS users (
    uid INTEGER PRIMARY KEY AUTOINCREMENT,
    username varchar(10), 
    passwd varchar(10)
);


-- 创建智能家居状态表
CREATE TABLE IF NOT EXISTS Status (
    sid INTEGER PRIMARY KEY AUTOINCREMENT,
    uid INTEGER ,
    device_name varchar(10),
    device_state varchar(10),
    value varchar(10),
    mode varchar(10),
    FOREIGN KEY (uid) REFERENCES users (uid)
);

SELECT device_state FROM Status WHERE uid = 123 AND device_name = '智能灯';
SELECT device_state FROM Status WHERE uid = 123 AND device_name = '智能灯' ORDER BY sid DESC LIMIT 1;
UPDATE Status SET value = '12' , device_state = '开启' WHERE uid = 123 AND device_name = '智能灯';
``