Binarydata over QJsonObject becomes to big.

[themts]

Hey guys,

I have a websocket communication where I'm using QJsonDocument for serialization.
I also have to transmit binary-data so I encapsulate it as a base64 String.
I would expect a 33% data-increase over a direct binary transmission but my data becomes nearly 3 times as big:

Bin-Data around 236 kByte while Json-Data is around 631 kByte.
Am I doing something wrong?

QByteArray ba = qryAtt.value("attachment").toByteArray(); //get data from sql-query
qDebug() << "SIZE:" << ba.size(); //236432

QJsonObject obj {
  {"fileName", qryAtt.value("fileName").toString()},
  ...
  {"attachment", QString(ba.toBase64())}
};          

THX
mts

[JonB]

@themts
I don't know what you expect, but this seems to have nothing to do with JSON or websockets. Just look at the size of what ba.toBase64() returns.

[themts]

no, that is not the point.
The base64 itself has the size that I expected.
Binary: 236432
Base64: 315244
33% bigger

but why does my QJson object have a size of around 631000 byte ?

[jsulm]

@themts Store your JSON in a file and take a look at it to see what exactly is in there.

[themts]

that is a little bit strange.
The file itself has an expected size and also the content looks normal.
I created a file before I send the data and when I received the data. Both are identical.

BUT:

void ...onBinaryMessageReceived(const QByteArray &message)
{
    qDebug() << "onBinaryMessageReceived" << message.size(); // HERE it tells me 631476

    //Json
    QJsonDocument doc = QJsonDocument::fromBinaryData(message);

[Christian Ehrlicher]

Why do you use QJsonDocument::from/toBinaryData at all? QStrings are utf-16 encoded in binary representation so 2 * 315244 = 630488 bytes + rest.

[themts]

@Christian-Ehrlicher Yes! You are absolutely right... toJson converts to UTF-8 and so it is working as expected.
Thank you!