I need to pass structures between cpp and QML. If i use property i should create an individual set and get functions, My structure contains minimum 5 members so i felt it's not good to use set and get for all those members. Following is an example of what i am trying to do :
MyClass.h
#include <QObject>
#include <QDebug>
using namespace std;
struct MyStruct {
Q_GADGET
int m_val;
QString m_name1;
QString m_name2;
QString m_name3;
QString m_name4;
Q_PROPERTY(int val MEMBER m_val)
Q_PROPERTY(QString name1 MEMBER m_name1)
Q_PROPERTY(QString name2 MEMBER m_name2)
Q_PROPERTY(QString name3 MEMBER m_name3)
Q_PROPERTY(QString name4 MEMBER m_name4)
};
class MyClass:public QObject
{
Q_OBJECT
Q_PROPERTY(MyStruct mystr READ getMyStruct
WRITE setMyStruct NOTIFY myStructChanged)
public:
explicit MyClass(QObject *parent = nullptr);
MyStruct strObj;
// Edit: changed get function
MyStruct getMyStruct() const
{
return strObj;
}
// Edit: Added set function
void setMyStruct(myStruct val)
{
mystr = val;
emit myStructChanged();
}
signals:
void myStructChanged();
}
main.cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include <QDebug>
#include <QObject>
#include "MyClass.h"
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
MyClass classObj;
engine.rootContext()->setContextProperty("classObj",&classObj);
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
if (engine.rootObjects().isEmpty())
return -1;
return app.exec();
}
Main.qml
import QtQuick 2.6
import QtQuick.Controls 2.2
import QtQuick.Window 2.3
ApplicationWindow {
id: applicationWindow
visible: true
width: 600
height: 400
title: qsTr("My App")
MainForm{
id : mainform
Component.onCompleted: {
console.log("name===="+classObj.mystr.name1)
//EDIT added more code to explain the use case.
classObj.myStr.name1 = "abc" //Calls setter
classObj.mystr.name2 = "ans" // Calls setter
}
}
}
If i print just (classObj.myVariant)
i am getting QVariant(MyStruct) but when i tried to access any parameter like classObj.myVariant.name1
i am getting "undefined" and also how to set a variant from QML?
[UPDATE] - Should also add MyStruct to Q_DECLARE_METATYPE as below: Q_DECLARE_METATYPE(MyStruct)
You need meta data to access C++ objects from QML.
For non QObject
derived, this is achieved by using the Q_GADGET
macro, and exposing the members as properties:
struct MyStruct {
Q_GADGET
int m_val;
QString m_name1;
QString m_name2;
QString m_name3;
QString m_name4;
Q_PROPERTY(int val MEMBER m_val)
Q_PROPERTY(QString name1 MEMBER m_name1)
Q_PROPERTY(QString name2 MEMBER m_name2)
Q_PROPERTY(QString name3 MEMBER m_name3)
Q_PROPERTY(QString name4 MEMBER m_name4)
};