arc/database/database_manager.cpp

#include "database_manager.h"
#include <QSqlError>
#include <QtCore/qcoreapplication.h>

DatabaseManager::DatabaseManager() {
    db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName(QCoreApplication::applicationDirPath()  + "/database/app_data.db");
    if (!db.open()) {
        qWarning() << "Ошибка открытия базы данных:" << db.lastError().text();
    }
}

DatabaseManager::~DatabaseManager() {
    if (db.isOpen()) {
        db.close();
    }
}

DatabaseManager& DatabaseManager::instance() {
    static DatabaseManager instance;
    return instance;
}

QSqlDatabase& DatabaseManager::database() {
    return db;
}