Json sending and receiving and finding keys inside json

[Kris Revi]

my question is does this affect when i try to

    QJsonDocument doc = QJsonDocument::fromJson(message);
    QJsonValue test = doc.object().value("001");

also this gives me no viable conversion from 'QString' to 'const QByteArray'

[JonB]

@Kris-Revi
[static]QJsonDocument QJsonDocument::fromJson(const QByteArray &json, QJsonParseError *error = nullptr) accepts input as a QByteArray:

Parses json as a UTF-8 encoded JSON document,

I don't know where you got your void MainWindow::onRequestedInfoReceived(QString message) with QString parameter from, data is sent around (serial ports, sockets) as bytes, so that's what it should be. If necessary, don't forget there is QByteArray QString::toUtf8() const.

[Kris Revi]

i can only set QString void MainWindow::onRequestedInfoReceived(QString message) it wont allow me to set QByteArray or bytes or anything realy :S

[JonB]

@Kris-Revi
I assume that method is a slot, and since you don't show the signal connection I cannot comment.

So did you try the QByteArray QString::toUtf8() const?

[Kris Revi]

@JonB
this is the Q_SIGNAL

void onRequestedInfoReceived(QString message);

this is the Q_SLOT

void onRequestedInfoReceived(QString message);

[JonB]

@Kris-Revi
Fine.
And for the third time of suggesting/asking: how are you finding using QByteArray QString::toUtf8() const on it then works for making your QString message acceptable to QJsonDocument::fromJson() with no error? I'm not going to repeat this further.

[Kris Revi]

@JonB wait... QByteArray QString::toUtf8() const ? :S

[Kris Revi]

@JonB did this

void MainWindow::onRequestedInfoReceived(QString message)
{
    //qDebug() << "[SOCKET][INFO] Requested Info : " << message;

    QByteArray messageArray = message.toUtf8();

    QJsonDocument doc = QJsonDocument::fromJson(messageArray);

    QJsonValue test = doc.object().value("001");

    qDebug() << "Board Type : " << test;
}

got

Board Type :  QJsonValue(undefined)

[fcarney]

What does

qDebug().noquote() << message; 

do?
It might remove the quoting altogether and make it more readable.

[JonB]

@Kris-Revi
Print out things like QJsonDocument::isNull(), QJsonDocument::isObject(), QJsonDocument::object(). What about looking at doc.object().keys() to see what is actually in there?

[Kris Revi]

the printing out part is realy not an issue :) i just noticed that there was added \ in the print out and i thought that that would affect the way im searching for keys!

[SGaist]

Hi,

Side questions:

• Where are you getting that JSON data from ?
• Do you receive it directly a QString ?
• If not, why not change the slot signature to use a QByteArray, or even better use a const reference on a QByteArray.

[Kris Revi]

@SGaist scroll to the top and you will see where i get that json from and the answer to the QString question :)

[JonB]

@Kris-Revi said in Json sending and receiving and finding keys inside json:

the printing out part is realy not an issue :)

Well, yes/no, but You are wanting to get back the doc2["300"] = DeviceType/"300":"ESP32" you put in, and you say you're not succedding with doc.object().value("001"), so you need to look at what the document you have parsed back has come out like.

EDIT Hang on, aren't you looking for the wrong thing? When you showed the string received earlier it was:

[SOCKET][INFO] Requested Info :  "{\"300\":\"ESP32\",\"301\":\"Matrix Display\",\"303\":\"Matrix\"}"

So why are you now asking for doc.object().value("001"); ? QJsonValue(undefined) looks about the right for that!

[Bonnie]

I'm guessing that OP get his data from QWebSocket.
So if he connects QWebSocket::textMessageReceived signal, then he'll get directly a QString.

[Kris Revi]

@JonB you are actualy correct! xD im looking for "303" NOT the "001" that is "Request Info"