Qt - Cannot Assign to Non-existent property (custom C++ class) - c++

Question

I am attempting to make a custom TCP widget for QML for my project (WebSocket sends a HTTP request, it doesn't allow me to send raw TCP packets). I created the "TCPSocketConnection" (named in cpp as TCPSocketConn) class and gave it some properties with placeholder methods and tried to insert it into QML. When I tried to use the class, I get the following error
qrc:/qml/qmlwebsocketclient/main.qml:43:9: Cannot assign to non-existent property "onTextMessageReceived"
I have a QML file like this
****************************************************************************/
import QtQuick 2.0
import QtWebSockets 1.0
import Qt.Comm 2.0
Rectangle {
width: 360
height: 360
TCPSocketConnection{
id: socket
url: "ff"
onTextMessageReceived: {
console.log("On Recieve: " + messsage)
}
}
}
The TCPSocketConnection is defined as follows
qmlRegisterType<TCPSocketConn>("Qt.Comm", 2, 0, "TCPSocketConnection");
in tcpsocketconn.h
#ifndef TCPSOCKETCONN_H
#define TCPSOCKETCONN_H
#include <QQuickItem>
class TCPSocketConn : public QQuickItem
{
Q_PROPERTY(QString url READ url WRITE a_1 NOTIFY a_2)
Q_PROPERTY(QString message READ message WRITE a_3 NOTIFY textMessageRecieved)
Q_PROPERTY(int status READ status WRITE a_4 NOTIFY statusChanged)
public:
explicit TCPSocketConn(QQuickItem *parent = 0);
QString url();
QString message();
int status();
signals:
void a_2();
void textMessageReceived();
void statusChanged();
public slots:
void a_1(QString);
void a_3(QString);
void a_4(int);
};
#endif // TCPSOCKETCONN_H
with a placeholder cpp file
#include "tcpsocketconn.h"
TCPSocketConn::TCPSocketConn(QQuickItem *parent) : QQuickItem(parent)
{
}
QString TCPSocketConn::url(){
return "";
}
QString TCPSocketConn::message(){
return "";
}
int TCPSocketConn::status(){
return 0;
}
void TCPSocketConn::a_1(QString d){
}
void TCPSocketConn::a_3(QString d){
}
void TCPSocketConn::a_4(int s){
}
void TCPSocketConn::textMessageReceived(){
}
void TCPSocketConn::statusChanged(){
}
void TCPSocketConn::a_2(){
}

Answer 1

You're missing the Q_OBJECT macro; it's not enough to just derive from a QObject subclass:
The Q_OBJECT macro must appear in the private section of a class definition that declares its own signals and slots or that uses other services provided by Qt's meta-object system.
There's also this paragraph:
Notice that the Q_OBJECT macro is mandatory for any object that implements signals, slots or properties. You also need to run the Meta Object Compiler on the source file. We strongly recommend the use of this macro in all subclasses of QObject regardless of whether or not they actually use signals, slots and properties, since failure to do so may lead certain functions to exhibit strange behavior.
This is explained in more detail here.