Need help: Unable to assign [undefined] to QString

rylicx

Hey, I am new to Qt and so i want to make a little program.

A small table which outputs some data from a List.
But i am not able to print the data. What do I do wrong?

Thank you for helping!

Main.cpp:

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "getdata.h"
#include <QQmlContext>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    const char* ui = "GETDATA"; // @uri GETDATA
    qmlRegisterType <GetData> (ui, 1, 0, "GetData");

    GetData* getData = new GetData;

    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("dataProvider", getData);
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

getdata.h

#ifndef GETDATA_H
#define GETDATA_H

#include <QList>
#include <QObject>

class GetData : public QObject
{
    public:
        GetData();

        Q_PROPERTY(QString name READ getName)
        QString name = "x";

    public slots:
        QString getName();
};

#endif // GETDATA_H

getdata.cpp

#include "getdata.h"

GetData::GetData()
{
}

QString GetData::getName(){
    return name;
}

QML- Main File:

import QtQuick 2.11
import QtQuick.Window 2.11
import GETDATA 1.0

Window {
    id: root
    visible: true
    width: 840
    height: 480
    title: qsTr("Rennliste")

    GetData {
        id: m_data;
    }

    Column{
        id: finalListColumn
        spacing: 5

        RowItem{
            placeText: "Platzierung"
            pointsText: "Gesamtpunkte"
            nameText: "Name"
            fontSize: 12
        }
        Repeater{
            model: 3
            RowItem{
                placeText: index
                pointsText: ""
                nameText: m_data.name
                fontSize: 9
            }
        }
    }
}

QML - RowItem:

import QtQuick 2.0

Row {
    id: finalList
    spacing: 5

    property string placeText
    property string pointsText
    property string nameText

    property int fontSize

    Rectangle{
        id: place;
        width: 150;
        height: 30;

        Text {
            text: placeText;
            font.pointSize: fontSize;
        }
    }
    Rectangle{
        id: points;
        width: 150;
        height: 30;
        Text {
            text: pointsText;
            font.pointSize: fontSize;
        }
    }
    Rectangle{
        id: name;
        width: 150;
        height: 30;
        Text {
            text: nameText;
            font.pointSize: fontSize;
        }
    }
}

sierdzio

Where does QML engine locate that error? Can you indicate that line in source you pasted?

Issues I see are:

you create 2 separate GetData objects (one in QML m_data, one in C++ dataProvider), but use only one of them (the QML one)
your GetData is missing Q_OBJECT macro
getName() method is not const
name property is not marked as CONSTANT
GetData constructor does not initialize it's base class (QObject)
not all user-visible strings marked with qsTr()

rylicx

Hey~
i corrected the issues and now it works fine!
Thank you so much!

Jaswenth S

@rylicx
hi buddy
I am beginner in Qt and I am facing the same error like "Unable to assign [undefined] to int"
and while printing that in console I get a garbage value like "-842150451".
I was stuck here , help me through this

jsulm

@Jaswenth-S Please post the relevant code.

Jaswenth S

@jsulm Thanks for your time , I solved it bro and sorry for the late reply

K Pradeep Kumar Reddy

@Jaswenth-S How did you solve it ?