DATABASE.H

#ifndef DATABASE_H
#define DATABASE_H

#include <QObject>
#include <QSqlDatabase>
#include <QDebug>
#include <QSqlError>
#include <QSqlQuery>

#include "docs.h"

class Database : public QObject
{
    Q_OBJECT
public:
    explicit Database(QObject *parent = 0);
    Q_INVOKABLE QVariant getAll();

private:
    QSqlDatabase db;
};

#endif // DATABASE_H

DATABASE.CPP

#include "database.h"

Database::Database(QObject *parent) : QObject(parent)
{
    db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("doctor.db");
}

QVariant Database::getAll()
{
    QList<Docs*> docs;
    if (db.open()) {
        QSqlQuery qry("SELECT * FROM docs;");
        if (!qry.lastError().isValid()) {
            while (qry.next()) {
                docs.append(new Docs(qry.value(0).toInt(),
                                     qry.value(1).toString(),
                                     qry.value(2).toString()));
            }
        } else {
            qDebug() << qry.lastError().text();
        }

    } else {
        qDebug() << db.lastError().text();
    }

    return QVariant::fromValue(docs);
}