CODEWITHSUNDEEP
c++qtclassqml
Morteza M
Morteza M

Reputation: 176

Use static property of a c++ class in qml

I have a c++ class like this:

class MyClass : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString P1 READ getP1)
    Q_PROPERTY(QString P2 READ getP2)
public:
    inline explicit MyClass(QObject *parent = nullptr) : QObject(parent) {}

    inline static const QString P1 = "something1";
    inline static const QString P2 = "something2";

    Q_INVOKABLE inline static QString getP1() {return P1;}
    Q_INVOKABLE inline static QString getP2() {return P2;}
};

And I use it in other c++ classes and it's Ok. Now, I want to use P1 and P2 in my qml file too. So, I have in main.cpp:

qmlRegisterType<MyClass>("com.MyClass", 1, 0, "MyClass");

And in my qml file:

import com.MyClass 1.0
.
.
.
console.log(MyClass.P1);
console.log(MyClass.getP2);

After running code, console show undefined for both of them! And MyClass.getP2() cause following error:

TypeError: Property 'getP2' of object [object Object] is not a function

How can I use of P1 and P2 in qml?

Solution:

Based on @pooya13 answer, I put this in main.cpp:

qmlRegisterSingletonType<MyClass>("com.MyClass", 1, 0, "MyClass",[](QQmlEngine *engine, QJSEngine *scriptEngine) -> QObject * {
    Q_UNUSED(engine)
    Q_UNUSED(scriptEngine)

    MyClass *example = new MyClass();
    return example;
});

So, I could use MyClass.P1 in qml file.

Upvotes: 0

Views: 1591

Answers (1)

pooya13
pooya13

Reputation: 2691

As folibis pointed out, it seems that you are using MyClass as a QML singleton (qmlRegisterSingletonInstance or qmlRegisterSingletonType):

// Does not need to be instantiated in QML (`MyClass` refers to registered singleton object)
console.log(MyClass.prop)
console.log(MyClass.getProp())

whereas you are registering it as a regular type:

// Needs to be instantiated in QML (`MyClass` refers to registered type)
MyClass {
   Component.onCompleted: {
      console.log(prop)
      console.log(getProp())
   }
}

Upvotes: 1

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