Assertion failure when calling "initializeGLFunctions()"

Question

I'm currently trying to learn how to use QTWidgets (version 6.4.2) in C++ in VS2022. Right now, I'm trying to just run a simple ui I created in the QT designer. On the window, I have a QOpenGLWidget that I want to use to display graphics. I have this widget promoted as a MyOpenGLWidget. My issue is that when I call "initializeOpenGLFunctions()" in "initializeGL()" the code breaks with the following error:

ASSERT: "context" in file qopenglfunctions.cpp, line 155

I've tried looking through the QOpenGLFunctions page on the qt website and couldn't find any information related to this.

Here is my code:

MyOpenGLWidget.h

#pragma once

#include <QOpenGLWidget>
#include <qopenglfunctions>

class MyOpenGLWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
    Q_OBJECT
public:
    explicit MyOpenGLWidget(QWidget* parent = nullptr) : QOpenGLWidget(parent)
    {
        initializeGL();
    }

    ~MyOpenGLWidget()
    {

    }

    void Initialize()
    {
        initializeGL();
    }

protected:
    void initializeGL() 
    {
        initializeOpenGLFunctions(); // Code breaks when this is called
    }

    void paintGL() {}
    void resizeGL(int w, int h) {}

};

QT_OpenGL.h

class QT_OpenGL : public QMainWindow
{
    Q_OBJECT

public:
    QT_OpenGL(QWidget *parent = nullptr);
    ~QT_OpenGL();


private:
    Ui::QT_OpenGLClass * ui;

protected:

};

QT_OpenGL.cpp

#include "QT_OpenGL.h"

QT_OpenGL::QT_OpenGL(QWidget *parent)
    : QMainWindow(parent)
{
    ui = new Ui::QT_OpenGLClass();
    ui->setupUi(this);

}

QT_OpenGL::~QT_OpenGL()
{}

main.cpp

#include "QT_OpenGL.h"
#include <QtWidgets/QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QT_OpenGL w;
    w.show();
    return a.exec();
}

Answer 1

Thanks to @holtavolt 's comment, I was able to gain some insight from the example he provided and therefore was able to do some more digging until I found this QOpenGLWidget's context is null post. The problem was me calling initializeGL in the constructor when the context was still NULL, so I removed the call since it would be called at some point when the window shows up.