C++ 为什么我的QString不能获取TextField的值？

我试图将TextField的值传递给字符串，我相信源代码是正确的，但是当我将值插入TextField并单击按钮时，它不会返回任何结果，但是如果我在 TextField{Text:Example}，它返回：Example，有什么想法吗

FirstPage.qml

Item {

Rectangle {
    anchors.fill: parent

    ColumnLayout {
        id: layoutLogin
        anchors.centerIn: parent
        anchors.margins: 3
        spacing: 3

        TextField {
            objectName: "login"
            Layout.fillWidth: true
            placeholderText: "Username"
        }

        TextField {
            property string password: text
            objectName: "passwordd"
            Layout.fillWidth: true
            placeholderText: "Password"
            echoMode: TextInput.Password
        }

        Button {
            id: proccessButton
            text: "Login"
            Layout.fillWidth: true
            onClicked: Login.test()
        }
      }
   }
}

login.cpp：

Login::Login() {
QQuickView view;
view.setSource(QUrl(QStringLiteral("qrc:/FirstPage.qml")));
QObject *object = view.rootObject();
QObject *login = object->findChild<QObject*>("login");
QObject *password = object->findChild<QObject*>("password");
login_u = login->property("login").toString();
password_u = password->property("password").toString();}

void Login::test(){
    qDebug() << "user:" << login_u;
    qDebug() << "password" << password_u;
}

---

我认为财产名称应该是文本。 试试这个：

login_u = login->property("text").toString();
password_u = password->property("text").toString();

我意识到您正在登录类的构造函数中获取值。 应在调用测试时获取

void Login::test()
{
    QQuickItem *object = m_view->rootObject();
    QObject *login = object->findChild<QObject*>("login");
    QObject *password = object->findChild<QObject*>("password");
    login_u = login->property("text").toString();
    password_u = password->property("text").toString();

    qDebug() << "user:" << login_u;
    qDebug() << "password" << password_u;
}

---

它在这里起作用了

我的答案将进一步尝试解决背景问题，即如何正确地从C++获取QML数据

第一个任务是实现一个从QObject继承的类，并处理用户名和密码属性，如下所示：

在这个类中，我们必须使用Q_PROPERTY宏公开属性，如果我们希望从QML调用函数，那么它前面必须有Q_INVOKABLE

---

完整的示例可以在下面的

中找到，您在哪里触发登录构造函数来检索值？这不应该在测试操作中进行吗？您可以放置一个可复制的代码，您已经消除了一些重要的细节。我尝试@user0042，结果相同。@Césaraugus尝试您的解决方案，如果您有任何问题，请告诉我，以便我可以帮助您输入密码字段。objectName:objectName:passwordd中有一个输入错误

void Login::test()
{
    QQuickItem *object = m_view->rootObject();
    QObject *login = object->findChild<QObject*>("login");
    QObject *password = object->findChild<QObject*>("password");
    login_u = login->property("text").toString();
    password_u = password->property("text").toString();

    qDebug() << "user:" << login_u;
    qDebug() << "password" << password_u;
}

#ifndef LOGIN_H
#define LOGIN_H

#include <QObject>

#include <QDebug>

class Login : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString username READ username WRITE setUsername NOTIFY usernameChanged)
    Q_PROPERTY(QString password READ password WRITE setPassword NOTIFY passwordChanged)
public:
    explicit Login(QObject *parent = nullptr):QObject(parent){

    }
    Q_INVOKABLE void test(){
        qDebug()<<mUsername<<mPassword;
    }

    QString username() const{
        return mUsername;
    }

    void setUsername(const QString &username){
        if(mUsername == username)
            return;
        mUsername = username;
        emit usernameChanged(mUsername);
    }


    QString password() const{
        return mPassword;
    }

    void setPassword(const QString &password)
    {
        if(mPassword == password)
            return;
        mPassword = password;
        emit passwordChanged(mPassword);
    }

signals:
    void usernameChanged(QString username);
    void passwordChanged(QString password);
private:
    QString mUsername;
    QString mPassword;
};


#endif // LOGIN_H

#include "login.h"

#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    qmlRegisterType<Login>("com.examples.login", 1, 0, "Login");
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

import QtQuick 2.6
import QtQuick.Window 2.2
import QtQuick.Controls 1.4
import QtQuick.Layouts 1.3
import com.examples.login 1.0

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Login")

    Login{
        id: login
        username: usernameField.text
        password: passwordField.text          
    }

    Rectangle {
        anchors.fill: parent

        ColumnLayout {
            id: layoutLogin
            anchors.centerIn: parent
            anchors.margins: 3
            spacing: 3

            TextField {
                id: usernameField
                textColor: "black"
                Layout.fillWidth: true
                placeholderText: "Username"
            }

            TextField {
                id: passwordField
                Layout.fillWidth: true
                placeholderText: "Password"
                echoMode: TextInput.Password
                textColor: "black"
            }

            Button {
                id: proccessButton
                text: "Login"
                Layout.fillWidth: true
                onClicked: login.test()

            }
        }
    }
}