Question

我正在尝试将TextField的值传递给String，我相信Source是正确的，但是当我将“value”插入TextField并单击按钮时，它什么也没有返回，但如果我设置了这个值 TextField {Text：“Example”}，它返回：“示例”，任何想法？

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;
}

单击“按钮”时的输出：

user: ""
password ""

Answer 1

我的答案会更深入地尝试解决背景问题，即如何正确地从C ++获取QML数据。

第一项任务是实现一个继承自QObject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，如果我们想要从QML调用一个函数，那么它必须以Q_INVOKABLE开头。

#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

然后我们使用qmlRegisterType在QML旁边注册它，所以现在这是一个QML库

#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();
}

最后我们在qml端使用它们来分配相应的连接

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()

            }
        }
    }
}

完整示例可在以下link

中找到

Answer 2

我认为属性名称应该是文本。试试这个：

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

我意识到你正在获取Login类的构造函数中的值。它应该在调用test（）时获得。

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;
}

它在这里工作

为什么我的QString不能获得TextField的值？

2 个答案: