qmlRegisterType => QML module not found. How to specify the path to the object ?

fcarney

Wait, where did you specify Q_INVOKABLE? It needs to be in the class definition, not in the cpp file.

So in your class:

class MainModelView
{
...
public:
  Q_INVOKABLE double get_scale(void);
...
};

Quentin91

@fcarney in both the declarations and definitions... I'll try to delete the Q_INVOKABLE from the cpp

Same error. The presence of the Q_INVOKABLE at the beginning of the definition doesn't change anything.
Unable to assign [undefined] to double

fcarney

I would backup and create a test project with the smallest amount of code. Then share that so we can see what is going on. If I run into something that "should work" I create test projects and test those out. Usually I either find the problem, or have an easy way to show others that there is indeed a problem. There are a lot of things that could cause objects to not be defined at the proper time. Making a minimal example helps other people help you.

J.Hilk

@Quentin91
can you share some more code? preferable something compileable so we can take a closer look at it ;-)

Quentin91

@J.Hilk said in qmlRegisterType => QML module not found. How to specify the path to the object ?:

@Quentin91
can you share some more code? preferable something compileable so we can take a closer look at it ;-)

@fcarney said in qmlRegisterType => QML module not found. How to specify the path to the object ?:

I would backup and create a test project with the smallest amount of code. Then share that so we can see what is going on. If I run into something that "should work" I create test projects and test those out. Usually I either find the problem, or have an easy way to show others that there is indeed a problem. There are a lot of things that could cause objects to not be defined at the proper time. Making a minimal example helps other people help you.

Thank you very much for your help

Ok, i made a new project in my solution. All the source, header and qml files are in the base folder. Only the executable is in a bin folder.

before showing the code, here are the problems. First, when I import my c++ type at the beginning of the qml, QML module not found but I still can launch the program with this error. When I use my type, Error : cannot assign [undefined] to bool

Here is miniModel.h

#ifndef _MINIMODEL_H_
#define _MINIMODEL_H_

#include <stdlib.h>
#include <stdio.h>
#include <iostream>

#include <string>

#include <QtGui/qguiapplication.h> 
#include <QtQml/qqmlcontext.h>
#include <QtQml/qqmlapplicationengine.h>
#include <QtCore/qdebug.h>
#include <QtCore/qobject.h>
#include <QtCore/qvariant.h>

class MiniModel : public QObject
{
	Q_OBJECT
	Q_PROPERTY(bool miniboule READ getMiniboule WRITE setMiniboule NOTIFY minibouleChanged)
public:
	MiniModel();

	bool getMiniboule();
	void setMiniboule(bool bouboule);

public slots:
signals:
	void minibouleChanged();

private:
	bool m_miniboule;
};

#endif

here is miniModel.cpp

#include "miniModel.h"

MiniModel::MiniModel():m_miniboule(true)
{
}

bool MiniModel::getMiniboule() {
	return m_miniboule;
}

void MiniModel::setMiniboule(bool bouboule){
	m_miniboule = bouboule;
	emit minibouleChanged();
}

main.cpp

#include "miniModel.h"

int main(int argc=0, char* argv[]=nullptr)
{
	QGuiApplication app(argc, argv);

	qmlRegisterType<MiniModel>("myModel.miniModel", 1, 0, "MiniModel");
	QQmlApplicationEngine engine;
	engine.addImportPath(QStringLiteral("..\\..\\..\\..\\Tools\\Qt\\5.12.0\\x64\\5.12.0\\msvc2017_64\\qml"));
	engine.load(QUrl(QStringLiteral("..\\..\\..\\miniModel.qml")));

	return app.exec();
}

QML code


import QtQuick 2.5
import QtQuick.Window 2.5
import QtQuick.Controls 1.4

import myModel.miniModel 1.0//QML module not found
ApplicationWindow {
    id: root
    width: 300
    height: 480
    Text{
       id: textTest
       x: 62
       y: 75
       color: "#d21616"
       text:  "vanilla"
       visible: false
    }
    MouseArea{
        onClicked: testText.visible=  MiniModel.getMiniboule//the boolean I want to acess, defined to true
    }
}

J.Hilk

@Quentin91

couple of things, that cause this error.

First of, MiniModel is not a Signelton nor a context property but a registered type.

So you'll have to instantiate the type in your QML code

ApplicationWindow {
    id: root
    width: 300
    height: 480
    visible:true
    Text{
       id: testText
       x: 62
       y: 75
       color: "#d21616"
       text:  "vanilla"
       visible: false
    }

    MiniModel{
        id:mModel
    }

    MouseArea{
        anchors.fill: parent
        onClicked: testText.visible=  mModel.miniboule 
    }
}

Secondly, getMiniboule() is the getter function for the miniboule property. You're not supposed to call that manually, but rather let the property system handle that:

Q_PROPERTY(bool miniboule READ getMiniboule WRITE setMiniboule NOTIFY minibouleChanged)

miniboule -> property name in QML 
getMiniboule -> c++ getter function name
setMiniboule -> c++ setter function name 

-----
//in QML set value
mModel.miniboule = true

//read the value
var a = mModel.miniboule

Quentin91

@J.Hilk ok, I see, thank you very much ! so I have to use another way to communicate...
i don't want to instanciate my type in the QML. My job is to transform a QML python application into C ++ QML. And the QML I will use does not instanciate the types.
This is an extract of the python code

module = importlib.import_module('models.'+self.model_file)
           self.main_model = module.MainModel( self )
           self.rootContext().setContextProperty( 'mainModel', self.main_model )
           self.statusChanged.connect( self.main_model.onStatusViewChanged )

So I thought I had to use setContextProperty in C++ too. Should I use a singleton instead ? If so, I tried. There it is :

I followed the example of the doc here https://doc.qt.io/qt-5/qtqml-cppintegration-definetypes.html

miniModel.h (the singleton)

#ifndef _MINIMODEL_H_
#define _MINIMODEL_H_
#include <stdlib.h>
#include <stdio.h>
#include <iostream>
#include <string>
#include <QtGui/qguiapplication.h> 
#include <QtQml/qqmlcontext.h>
#include <QtQml/qqmlapplicationengine.h>
#include <QtCore/qdebug.h>
#include <QtCore/qobject.h>
#include <QtCore/qvariant.h>

class MiniModel : public QObject
{
	Q_OBJECT
	Q_PROPERTY(bool miniboule READ miniboule WRITE setMiniboule NOTIFY minibouleChanged)
public:
	MiniModel();
	bool miniboule();
	void setMiniboule(bool bouboule);
signals:
	void minibouleChanged();
private:
	bool m_miniboule;
};

#endif

miniModel.cpp

#include "miniModel.h"

MiniModel::MiniModel():m_miniboule(true)
{
}
bool MiniModel::miniboule() {
	return m_miniboule;
}
void MiniModel::setMiniboule(bool bouboule){
	m_miniboule = bouboule;
	emit minibouleChanged();
}

main.cpp v1 : singleton using a QObject

#include "miniModel.h"

//defining a miniModel instance as a singleton
static QObject* mp_singleton(QQmlEngine* engine, QJSEngine* scriptEngine)
{
	Q_UNUSED(engine)
	Q_UNUSED(scriptEngine)

	MiniModel* miniSingleton = new MiniModel();
	return miniSingleton;
}

int main(int argc=0, char* argv[]=nullptr)
{
	printf("\n launching \n");
	QGuiApplication app(argc, argv);

	qmlRegisterSingletonType<MiniModel>("myModel.miniModel", 1, 0, "MiniModel",mp_singleton);

	QQmlApplicationEngine engine;

	engine.addImportPath(QStringLiteral("..\\..\\..\\..\\Tools\\Qt\\5.12.0\\x64\\5.12.0\\msvc2017_64\\qml"));
	engine.load(QUrl(QStringLiteral("..\\..\\..\\miniModel.qml")));

	return app.exec();
}

main.cpp v2 : singletin using QJSValue

#include "miniModel.h"

static QJSValue m_singletonModel(QQmlEngine* engine, QJSEngine* scriptEngine) {
	Q_UNUSED(engine)

	static bool m_miniboule;
	QJSValue miniModel = scriptEngine->newObject();
	miniModel.setProperty("miniboule", m_miniboule);
	return miniModel;
}

int main(int argc = 0, char* argv[] = nullptr)
{
	printf("\n launching \n");
	QGuiApplication app(argc, argv);

	qmlRegisterSingletonType("myModel.miniModel", 1, 0, "MiniModel", m_singletonModel);

	QQmlApplicationEngine engine;

	engine.addImportPath(QStringLiteral("..\\..\\..\\..\\Tools\\Qt\\5.12.0\\x64\\5.12.0\\msvc2017_64\\qml"));
	engine.load(QUrl(QStringLiteral("..\\..\\..\\miniModel.qml")));

	return app.exec();
}

and the QML. be careful, it's tough

import QtQuick 2.5
import QtQuick.Window 2.5
import QtQuick.Controls 1.4

import myModel.miniModel 1.0 as MyModel
ApplicationWindow {
    id: root
    width: 300
    height: 480
    visible:true
    Text{
       id: textTest
       x: 62
       y: 75
       color: "#d21616"
       text:  "vanilla"
       visible: false//the text is supposed to appear when clicking in the mouseArea
    }
    MouseArea{
        anchors.fill: parent
        onClicked: textTest.visible=  MyModel.Minimodel.miniboule//the boolean I want to acess, defined to true
    }
}

now, the error changed, since I called MyModel.MiniModel.miniboule instead of just MiniModel.miniboule
the error is TypeError: Cannot read property 'miniboule' of undefined

ps : the topic is now the same than this one. I made another topic for another error, but the errors are actually linked (or the same) : https://forum.qt.io/topic/102730/error-cannot-assign-undefined-to-qstring-while-communicating-between-c-and-qml

fcarney

@Quentin91 said in qmlRegisterType => QML module not found. How to specify the path to the object ?:

import myModel.miniModel 1.0 as MyModel

The way you have written this MyModel is the MiniModel.
So you should be accessing miniboule like this:

onClicked: textTest.visible=  MyModel.miniboule

Quentin91

@fcarney

onClicked: textTest.visible= MyModel.miniboule

When I write it this way, the error is cannot assign [undefined] to bool
Else, when writing MyModel.MiniModel.miniboule, it says ContentItem: Binding loop detected for property "implicitWidth but it works !

It's been three days that I'm working on that version, singleton, all day and I have no idea why it works only now... but anyway, thank you very much for your help !

J.Hilk

@Quentin91

//main.cpp
#include <QApplication>
#include <QQmlApplicationEngine>

#include "minimodel.h"

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

    QQmlApplicationEngine engine;
    MiniModel mModel;
    engine.rootContext()->setContextProperty("MiniModel", &mModel);

    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

//main.qml
import QtQuick 2.5
import QtQuick.Window 2.5
import QtQuick.Controls 1.4

ApplicationWindow {
    id: root
    width: 300
    height: 480
    visible:true
    Text{
       id: testText
       x: 62
       y: 75
       color: "#d21616"
       text:  "vanilla"
       visible: false
    }


    MouseArea{
        anchors.fill: parent
        onClicked: testText.visible=  MiniModel.miniboule
    }
}

works fine