app/sources/main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QSqlDatabase>
#include <QSqlError>
#include <QDebug>
#include <QFile>
#include <QDir>
#include <QStandardPaths>
#include <QtWebView/QtWebView>

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QGuiApplication>
#include <QQuickView>
#include <QStandardPaths>
#include <QtQml>
#include <QtNetwork>
#include <QQmlApplicationEngine>
#include <QFile>
#include <QDesktopServices>

#include <QtCore/QUrl>
#include <QtCore/QCommandLineOption>
#include <QtCore/QCommandLineParser>
#include <QGuiApplication>
#include <QStyleHints>
#include <QScreen>
#include <QQmlApplicationEngine>
#include <QtQml/QQmlContext>
#include <QtWebView/QtWebView>
#ifdef Q_OS_ANDROID
    #include <QtAndroidExtras>
#endif
#include "headers/sqlstoragemodel.h"
#include "headers/sqlprofilemodel.h"
#include "headers/buzzerconn.h"
#include "headers/appsettings.h"

static void connectToDatabase()
{
    QSqlDatabase database = QSqlDatabase::database();
    if (!database.isValid()) {
        database = QSqlDatabase::addDatabase("QSQLITE");
        if (!database.isValid())
            qFatal("Cannot add database: %s", qPrintable(database.lastError().text()));
    }

    const QDir writeDir = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);
    qDebug() << writeDir;
    if (!writeDir.mkpath("."))
        qFatal("Failed to create writable directory at %s", qPrintable(writeDir.absolutePath()));

    // Ensure that we have a writable location on all devices.
    const QString fileName = writeDir.absolutePath() + "/chat-database.sqlite3";
    //QFile::remove(fileName);
    // When using the SQLite driver, open() will create the SQLite database if it doesn't exist.
    database.setDatabaseName(fileName);
    if (!database.open()) {
        QFile::remove(fileName);
        qFatal("Cannot open database: %s", qPrintable(database.lastError().text()));

    }
}

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

    QGuiApplication app(argc, argv);

    #ifdef Q_OS_ANDROID
    //set the standard volume to media
        QAndroidJniObject jactivity=QtAndroid::androidActivity();
        if(jactivity.isValid())
        jactivity.callMethod<void>("setVolumeControlStream","(I)V",3);
    #endif

    connectToDatabase();
    BuzzerConn * pBuzzerConn = new BuzzerConn;
    AppSettings * pAppSettings = new AppSettings();

    //setup the sql storage model as a qml model
    qmlRegisterType<SqlProfileModel>("com.itsblue.speedclimbingstopwatch", 1, 0, "SqlProfileModel");
    qmlRegisterType<SqlStorageModel>("com.itsblue.speedclimbingstopwatch", 1, 0, "SqlStorageModel");

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

    engine.rootContext()->setContextProperty("_cppBuzzerConn", pBuzzerConn);
    engine.rootContext()->setContextProperty("_cppAppSettings", pAppSettings);

    return app.exec();
}