"TypeError: Property 'someFunction' of object [object Object] is not a function" and "TypeError: Type error" when exposing C++ class to QML

Question

I keep getting this error for some reason. Everything seems to work when I use this to pass a C++ class instance to QML.

main.cpp:

QQmlApplicationEngine engine;
gui::Wallet wallet;
engine.rootContext()->setContextProperty("Wallet", &wallet);

But what I really want to do is create an uncreatable type and import it in my main.qml. In my main.cpp file, I've replaced the previous code with this line: qmlRegisterUncreatableType<gui::Wallet>("neroshop.Wallet", 1, 0, "Wallet", "Wallet cannot be instantiated directly.");

main.qml:

import QtQuick 2.12
import QtQuick.Controls 2.12

import neroshop.Wallet 1.0



ApplicationWindow {
    id: mainWindow
    visible: true
    title: qsTr("neroshop")
    width: 1280
    height: 720
    minimumWidth: 850
    minimumHeight: 500    
    color: "#ffffff"

                NeroshopComponents.ProgressBar {
                    id: moneroDaemonSyncBar
                    radius: daemonSyncBar.radius
                    foregroundColor: NeroshopComponents.Style.moneroOrangeColor
                    backgroundColor: "#8c8c8c"
                    hoverEnabled: true
                    anchors.verticalCenter: parent.verticalCenter
                    
                    Timer {
                        interval: 1 // trigger every x miliseconds
                        running: true
                        repeat: true
                        onTriggered: {
                            moneroDaemonSyncBar.value = Wallet.getSyncPercentage()
                        }
                    }                                    
                }
}

Header where I declare my wallet class:

#pragma once

#ifndef WALLET_PROXY_HPP_NEROSHOP
#define WALLET_PROXY_HPP_NEROSHOP

#include <QObject>
#include <QString>
#include <QStringList>
#include <QVariant>

#include <memory> // std::unique_ptr

#include "../core/wallet.hpp"

namespace neroshop {

namespace gui { // or just remove the "gui" namespace and rename gui::Wallet to WalletProxy?

class Wallet : public QObject, public neroshop::Wallet {
    Q_OBJECT 
    // properties (for use in QML)
    Q_PROPERTY(neroshop::Wallet* wallet READ getWallet WRITE setWallet);// NOTIFY wallet_changed);
    //Q_PROPERTY(<type> <variable_name> READ <get_function_name>)
public:    
    enum KeyfileStatus {
        KeyfileStatus_Ok = 0,
        KeyfileStatus_Wrong_Password,
        KeyfileStatus_No_Matching_Passwords,
        KeyfileStatus_Exists,
    };
    Q_ENUM(KeyfileStatus)
    // functions (for use in QML)
    ////explicit Wallet(QObject* parent = 0);
    Q_INVOKABLE int createRandomWallet(const QString& password, const QString& confirm_pwd, const QString& path) const;
    Q_INVOKABLE void closeWallet(bool save = false);
    Q_INVOKABLE QVariantMap createUniqueSubaddressObject(unsigned int account_idx, const QString & label = "");
    Q_INVOKABLE double getSyncPercentage() const;
    Q_INVOKABLE unsigned int getSyncHeight() const;
    Q_INVOKABLE unsigned int getSyncStartHeight() const;
    Q_INVOKABLE unsigned int getSyncEndHeight() const;
    Q_INVOKABLE QString getSyncMessage() const;
    Q_INVOKABLE QString getMnemonic() const;
    Q_INVOKABLE QStringList getMnemonicList() const;
    Q_INVOKABLE QString getPrimaryAddress() const;

    Q_INVOKABLE QStringList getAddressesAll() const;
    Q_INVOKABLE QStringList getAddressesUsed() const;
    Q_INVOKABLE QStringList getAddressesUnused() const;
    Q_INVOKABLE double getBalanceLocked(unsigned int account_index) const;
    Q_INVOKABLE double getBalanceLocked(unsigned int account_index, unsigned int subaddress_index) const;
    Q_INVOKABLE double getBalanceUnlocked(unsigned int account_index) const;
    Q_INVOKABLE double getBalanceUnlocked(unsigned int account_index, unsigned int subaddress_index) const;
    Q_INVOKABLE neroshop::Wallet * getWallet() const;
    Q_INVOKABLE void setWallet(const neroshop::Wallet* wallet);

    Q_INVOKABLE void daemonExecute(const QString& ip, const QString& port, bool confirm_external_bind, bool restricted_rpc, bool remote, QString data_dir, QString network_type, unsigned int restore_height);// const;
    Q_INVOKABLE bool isGenerated() const;
    Q_INVOKABLE bool fileExists(const QString& filename) const;
private:
    std::unique_ptr<neroshop::Wallet> wallet;
public:
    Wallet();
    ~Wallet();
};

}

}

#endif

I was expecting it to work right away but instead I got this error:

qrc:/qml/main.qml:186: TypeError: Property 'getSyncPercentage' of object [object Object] is not a function
qrc:/qml/main.qml:186: TypeError: Type error

getSyncPercentage is indeed a function attached to the Wallet class. I don't know why it does not recognize it as a function. Am I doing something wrong here?

Answer 1

Why do you use an uncreatable type? This is only usefull for e.g. enums. You then try to create an instance. To make that work you should use

 qmlRegisterType<gui::Wallet>("Wallet", 1, 0, "Wallet");

Or you can register a singleton instance, if you what just one instance of our class.