Serialization custom type

[ado130]

Hello,
I'm trying write to binary file my custom type, so I have:

typedef enum t_timeloopsStatus
{
    NOTHING = 0,
    UPDATED,
} t_timeloopsStatus;
 
typedef struct t_timeloops
{
    QString key;
    t_timeloopsStatus status;
} t_timeloops;
 
    QMap<QString, t_timeloops> _timeLoops;

typedef enum t_timeloopsStatus
{
    NOTHING = 0,
    UPDATED,
} t_timeloopsStatus;

typedef struct t_timeloops
{
    QString key;
    t_timeloopsStatus status;
} t_timeloops;

    QMap<QString, t_timeloops> _timeLoops;

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I know, that I have to overload << and >> operators

QDataStream &operator<<(QDataStream &out, const QMap<QString, t_timeloops> &timeloops);
QDataStream &operator>>(QDataStream &in, QMap<QString, t_timeloops> &timeloops);

QDataStream &operator<<(QDataStream &out, const QMap<QString, t_timeloops> &timeloops);
QDataStream &operator>>(QDataStream &in, QMap<QString, t_timeloops> &timeloops);

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but I have no idea how will looks function for that.

I found an original function for QMap and tried to rewrite it, but without success.

QDataStream &operator<<(QDataStream &out, const QMap<QString, t_timeloops> &timeloops)
{
    out << quint32(timeloops.size());
    typename QMap<QString, t_timeloops>::ConstIterator it = timeloops.end();
    typename QMap<QString, t_timeloops>::ConstIterator begin = timeloops.begin();
    while (it != begin) {
        --it;
        out << it.key() << it.value();
    }
    return out;
}
 
QDataStream &operator>>(QDataStream &in, QMap<QString, t_timeloops> &timeloops)
{
    QDataStream::Status oldStatus = in.status();
    in.resetStatus();
    timeloops.clear();
 
    quint32 n;
    in >> n;
 
    timeloops.detach();
    for (quint32 i = 0; i < n; ++i) {
        if (in.status() != QDataStream::Ok)
            break;
 
        QString key;
        t_timeloops value;
        in >> key >> value.key >> value.pad >> value.cylinder >> value.status;
        timeloops.insertMulti(key, value);
    }
    if (in.status() != QDataStream::Ok)
        timeloops.clear();
    if (oldStatus != QDataStream::Ok)
        in.setStatus(oldStatus);
    return in;
}

QDataStream &operator<<(QDataStream &out, const QMap<QString, t_timeloops> &timeloops)
{
    out << quint32(timeloops.size());
    typename QMap<QString, t_timeloops>::ConstIterator it = timeloops.end();
    typename QMap<QString, t_timeloops>::ConstIterator begin = timeloops.begin();
    while (it != begin) {
        --it;
        out << it.key() << it.value();
    }
    return out;
}

QDataStream &operator>>(QDataStream &in, QMap<QString, t_timeloops> &timeloops)
{
    QDataStream::Status oldStatus = in.status();
    in.resetStatus();
    timeloops.clear();

    quint32 n;
    in >> n;

    timeloops.detach();
    for (quint32 i = 0; i < n; ++i) {
        if (in.status() != QDataStream::Ok)
            break;

        QString key;
        t_timeloops value;
        in >> key >> value.key >> value.pad >> value.cylinder >> value.status;
        timeloops.insertMulti(key, value);
    }
    if (in.status() != QDataStream::Ok)
        timeloops.clear();
    if (oldStatus != QDataStream::Ok)
        in.setStatus(oldStatus);
    return in;
}

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Thanks for any help!