QT: How to replace number (Start, End) in a JSON from server - c++

Question

This is how my JSON file looks like. As you can see, the start_x, start_y, and end_x, end_y, degree_of_rotation is a number.
{
"ID" : "ROLL1",
"action" : "start",
"zone" :
{
"start_x" : 0,
"start_y" : 4,
"end_x" : 10,
"end_y" : 5,
"motion" :
{
"motion_type": "xxxxxx",
"degree_of_rotation": 30,
"rotation_direction": "yyyyyy",
"linear_direction": "+ve"
}
}
}
How can I replace and save the number in JSON from the server? Currently, this is what I have. Qt5 has a new JSON parser and I want to use it. The problem is that it isn't too clear about what the functions do
void JsonFileread::Json_File_Function()
{
try
{
qDebug() <<"file reading";
file.setFileName("/home/JSON/jsonfile.js");
file.open(QIODevice::ReadOnly | QIODevice::Text);
QFileDevice::FileError err = QFileDevice::NoError;
if(!file.open(QIODevice::ReadOnly | QIODevice::Text))
{
qDebug() <<"Could not open file : "<<file.fileName() <<"for reading :"<<file.errorString()<<endl;
errMsg =file.errorString();
err =file.error();
cout<<"err : "<<err<<endl;
}
settings = file.readAll();
if (file.error() != QFile::NoError) {
qDebug() << QString("Failed to read from file %1, error: %2").arg(file.fileName()).arg(file.errorString());
}
if (settings.isEmpty()) {
qDebug() << "No data was currently available for reading from file" << file.fileName();
}
file.close();
object = EchoClient::jsonstringflag;
QJsonDocument sd = QJsonDocument::fromJson(settings.toUtf8());
QJsonObject sett2 = sd.object();
QJsonValue mainid = sett2["ID"];
mainid = mainid.toString();
QJsonValue action = sett2["action"];
actionstring = action.toString();
QJsonValue value = sett2.value(QString("zone"));
QJsonObject item = value.toObject();
QJsonValue startx = item["start_x"];
startvaluex = startx.toInt();
QJsonValue starty = item["start_y"];
startvaluey = starty.toInt();
QJsonValue endx = item["end_x"];
endvaluex = endx.toInt();
xendvaluestring = endx.toString();
qWarning() << endvaluex<<endl;
QJsonValue endy = item["end_y"];
endvaluey = endy.toInt();
yendvaluestring = endy.toString();
qWarning() << endvaluey<<endl;
QJsonValue motion = item.value(QString("motion"));
QJsonObject motion_object = motion.toObject();
QJsonValue motiontype = motion_object["motion_type"];
motiontypestring = motiontype.toString();
QJsonValue directionlinear = motion_object["linear_direction"];
lineardirection = directionlinear.toString();
QJsonValue rotatingangle = motion_object["degree_of_rotation"];
angleofrotation = rotatingangle.toInt();
}
catch (QJsonParseError error)
{
qDebug() << error.errorString();
}
catch(...)
{
qDebug() << "due to some other error";
}
}
So help to solve the problem

Answer 1

You can write to a QJsonObject very similar to how you read its properties
QJsonObject obj;
obj["key"] = value;
Once you have built the QJsonObject tree, set the top level element on a QJsonDocument and use it to generate the JSON content.