Save QVector to JSON file

neda

Hi guys,
This code works but It'd be great if you could suggest a better code.

"QVector<QPointF>" is the best choice for hold points? (I have a lot of points (more than 1,000,000 points) and a lot of processes on points)

QJsonDocument JsonManager::vectorPointsToJsonDocument(QVector<QPointF> listPoints) {
    QVariantMap variantMap;
    for(int i=0;i<listPoints.size();i++){
        QJsonObject jsonObject;
        jsonObject["x"]=listPoints.at(i).x();
        jsonObject["y"]=listPoints.at(i).y();
        variantMap.insertMulti("point",jsonObject);
    }
    QJsonObject jsonObj=QJsonObject::fromVariantMap(variantMap);
...
...
.....

Christian Ehrlicher

Take a look at QJsonArray and the Save Game example: http://doc.qt.io/qt-5/qtcore-serialization-savegame-example.html

neda

@Christian-Ehrlicher
Thanks a lot
I see your link and write a new code.

QJsonArray array;
    foreach(const QPointF point,listPoints){
        QJsonObject pointObject;
        pointObject["x"]=point.x();
        pointObject["y"]=point.y();
       array.append(pointObject);
    }
    QJsonObject object;
    object["points"] = array;
    QJsonDocument saveDoc(object);
    saveJson(saveDoc,fileName);

lautaroleon

Hi. I spend some time making this small code to do a similar job in a different way. I hope someone can find it useful.

#include <QCoreApplication>
#include <iostream>
#include <QVector>
#include <QFile>
#include <QJsonDocument>
#include <QJsonValue>
#include <QJsonArray>
#include <QJsonObject>
#include <QDateTime>

QJsonDocument hacelawea(){

//dummy vector
    QVector<int> mivector;
    for (int i=0;i<20;i++) {
        mivector.append(i);
    }

    QJsonArray jsonarray;
    foreach(const int i, mivector){
        QJsonValue Val(mivector[i]);
        jsonarray.append(Val);
    }

    QJsonObject objetofinal;

    objetofinal[QDateTime::currentDateTime().toString("yyyy-MM-dd'_'hh:mm:ss")]=jsonarray;
    QJsonDocument jasonsavedoc(objetofinal);
    return jasonsavedoc;

}


int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    std::cout<<"hola hola"<<std::endl;

    QFile saveFile(QStringLiteral("save.json"));

    if (!saveFile.open(QIODevice::ReadWrite)) {
        qWarning("Couldn't open save file.");
    }

    for(int i; i<5;i++)saveFile.write(hacelawea().toJson());

    saveFile.close();

    //return a.exec();
    return 0;
}