Using QVector in Q_PROPERTY and accesing each data

I would like to update weekKm and weekTime to update automatically when I change any value in m_weekKmAndTime, but I am struggling with that. I would like to access it just like DbModel.weekKm(0), and have a value, not struggle with vars in QML and trying to get a value there.

.h:

Q_PROPERTY(QVector<QPair<int, int>> weekKmAndTime READ weekKmAndTime NOTIFY weekKmAndTimeChanged)
weekKm and weekTime are Q_INVOKABLE

.cpp:

QVector<QPair<int, int>> DataBaseModel::weekKmAndTime() const
{
    return m_weekKmAndTime;
}
int DataBaseModel::weekKm(int day) const
{
    return m_weekKmAndTime[day].first;
}
int DataBaseModel::weekTime(int day) const
{
    return m_weekKmAndTime[day].second;
}
void DataBaseModel::setWeek(QString day, int new_km, int new_time) {
    m_weekKmAndTime[returnNumberFromDay(day)] = qMakePair(new_km, new_time);
    qDebug() << new_km << " " << new_time;
    emit weekKmAndTimeChanged();
    emit weekKmChanged();//this on its own doesn't work
    emit weekTimeChanged();
}

Tried to figure out what do you want to achieve. Because I saw that you want to update individual components of the structure, I moved them into a separate class and not messing with QPair. Like this they have their own named properties and their notification signal can be connected to QML. I was lazy with the memory deallocation, so keep in mind that you need to do that.

#ifndef DATABASEMODEL_H
#define DATABASEMODEL_H

#include <QObject>
#include <QVector>
#include <QDebug>

class wkmt : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QVariant km READ km NOTIFY kmChanged)
    Q_PROPERTY(int time READ time NOTIFY timeChanged)
public:
    explicit wkmt(int km, int time, QObject*parent=nullptr) : mKM{km}, mTime{time}, QObject{parent}
    {}
    int km() const { return mKM; }
    void setKM(int km)
    {
        if(mKM==km)return;
        mKM = km;
        emit kmChanged();
    }

    void setTime(int time)
    {
        if(mTime==time)return;
        mTime = time;
        emit timeChanged();
    }

    int time() const { return mTime; }

signals:
    void kmChanged();
    void timeChanged();

private:
    int mKM;
    int mTime;
};

class DataBaseModel : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QVector<wkmt*> weekKmAndTime READ weekKmAndTime NOTIFY weekKmAndTimeChanged)
public:
    explicit DataBaseModel(QObject *parent = nullptr) : QObject{parent}
    {
        m_weekKmAndTime.push_back(new wkmt(0, 0));
        m_weekKmAndTime.push_back(new wkmt(0, 0));
        m_weekKmAndTime.push_back(new wkmt(0, 0));
        m_weekKmAndTime.push_back(new wkmt(0, 0));
        m_weekKmAndTime.push_back(new wkmt(0, 0));
        m_weekKmAndTime.push_back(new wkmt(0, 0));
        m_weekKmAndTime.push_back(new wkmt(0, 0));
        setWeek("Monday", 23, 99);
        setWeek("Tuesday", 23, 99);
        setWeek("Wednesday", 23, 99);
        setWeek("Thursday", 23, 99);
        setWeek("Friday", 23, 99);
        setWeek("Saturday", 23, 99);
        setWeek("Sunday", 23, 99);
    }
    QVector<wkmt*> weekKmAndTime() const
    {
        return m_weekKmAndTime;
    }

    int weekKm(int day) const
    {
        return m_weekKmAndTime[day]->km();
    }

    int weekTime(int day) const
    {
        return m_weekKmAndTime[day]->time();
    }

    Q_INVOKABLE void setWeek(QString day, int new_km, int new_time) {
        m_weekKmAndTime[returnNumberFromDay(day)] = new wkmt(new_km, new_time);
        emit weekKmAndTimeChanged();
    }

    int returnNumberFromDay(const QString& day)
    {
        QVector<QString> days;
        days << "Monday" <<  "Tuesday" << "Wednesday" << "Thursday" << "Friday" << "Saturday" << "Sunday";
        return days.indexOf(day);
    }

signals:
    void weekKmAndTimeChanged();

private:
    QVector<wkmt*> m_weekKmAndTime;
};

#endif // DATABASEMODEL_H

QML code:

import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Controls 2.12

Window {
    width: 640
    height: 480
    visible: true

    Column {
        Column {
            Repeater {
                model: dbModel.weekKmAndTime
                delegate: Row {
                    Text {
                        text: "km: " + dbModel.weekKmAndTime[index].km
                    }

                    Text {
                        text: ", time: " + dbModel.weekKmAndTime[index].time
                    }
                }
            }
        }

        Button {
            text: "Update Tuesday"
            onClicked: dbModel.setWeek("Tuesday", 88, 123);
        }
    }
}

The app looks like this and by pressing the button, it will update the second row (Tuesday)