QDataStream and QSql Object. Urgent!! please

[ruben.rodrigues]

Hi!

I need to pack and unpack a QSqlQuery or a QSqlResult into a QByteArray and using a QDataStream. I need this because later I am supposed to send/received the QByteArray through a tcp socket.

To pack the QSqlQuery I used the result() function:

QByteArray dataBlock;
QDataStream dataStream(&dataBlock, QIODevice::WriteOnly);
 
    dataStream << sqlQuery.result();
 
return dataBlock;

QByteArray dataBlock;
QDataStream dataStream(&dataBlock, QIODevice::WriteOnly);

    dataStream << sqlQuery.result();

return dataBlock;

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now when I try to do the opposite I get errors, QDataStream:perator :

QSqlResult *result;
QDataStream dataStream(&qba, QIODevice::ReadOnly);
 
     dataStream >> result; //error
 
_query = QSqlQuery(result);

QSqlResult *result;
QDataStream dataStream(&qba, QIODevice::ReadOnly);

     dataStream >> result; //error

_query = QSqlQuery(result);

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is there a solution or even a better way to do this?

thanks

[marcvanriet]

Have you checked what data is transferred ? I would be surprised if the actual SQL result is in there.

Anyway, since QSqlResult is an abstract interface class, you cannot use >> onto it I think.

See the documentation of QDataStream : "For any (other) Qt class you wnat to use with QDataStream, you have to provide the >> and << operators".

Regards,
Marc

[ChrisW67]

Stream the row and column count, then iterate through the result set and serialise each row, column by column. You can stream the QVariant values as-is, or convert them to desired types first. At the moment you are serialising the pointer returned by QSqlQuery::result().