QJson Qt5

qjson_qt5.cpp

#include <QApplication>
#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>
#include <QJsonParseError>
#include <QFile>
#include <QDebug>

struct DeskWallpaper {
    int width;
    int height;
    QString url;

    int previewWidth;
    int previewHeight;
    QString previewUrl;

    int thumbWidth;
    int thumbHeight;
    QString thumbUrl;

    void printAll() {
        qDebug() << "Image width: " << width;
        qDebug() << "Image height: " << height;
        qDebug() << "Image url: " << url;

        qDebug() << "Preview width: " << previewWidth;
        qDebug() << "Preview height: " << previewHeight;
        qDebug() << "Preview url: " << previewUrl;

        qDebug() << "Thumb width: " << thumbWidth;
        qDebug() << "Thumb height: " << thumbHeight;
        qDebug() << "Thumb url: " << thumbUrl;
    }
};

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);

    QFile jsonFile("random.json");

    if (!jsonFile.open(QIODevice::ReadOnly | QIODevice::Text))
    {
        qDebug() << "Unable to open file, exiting...";
        return 1005;
    }

    QByteArray jsonData = jsonFile.readAll();

    QJsonParseError *err = new QJsonParseError();

    QJsonDocument doc = QJsonDocument::fromJson(jsonData, err);

    if (err->error != 0)
        qDebug() << err->errorString();

    DeskWallpaper wallpaper;

    if (doc.isNull())
    {
        qDebug() << "Invalid json document, exiting...";
        return 1006;
    }
    else if (doc.isObject())
    {
        //get the jsonObject
        QJsonObject jObject = doc.object();

        //convert the json object to variantmap
        QVariantMap mainMap = jObject.toVariantMap();

        //get the "response" variant map
        QVariantMap responseMap = mainMap["response"].toMap();

        //get the width and height of image
        wallpaper.width = responseMap["width"].toInt();
        wallpaper.height = responseMap["height"].toInt();

        //get the image url
        QVariantMap imageMap = responseMap["image"].toMap();
        wallpaper.url = imageMap["url"].toString();

        //get the preview image details
        QVariantMap previewMap = imageMap["preview"].toMap();
        wallpaper.previewWidth = previewMap["width"].toInt();
        wallpaper.previewHeight = previewMap["height"].toInt();
        wallpaper.previewUrl = previewMap["url"].toString();

        //get the thumbnail details
        QVariantMap thumbMap = imageMap["thumb"].toMap();
        wallpaper.thumbWidth = thumbMap["width"].toInt();
        wallpaper.thumbHeight = thumbMap["height"].toInt();
        wallpaper.thumbUrl = thumbMap["url"].toString();

        wallpaper.printAll();
    }
    else if (doc.isArray())
    {
        qDebug() << "Are you sure this is the json from Desktoppr? exiting...";
        return 1007;
    }
    else if (doc.isEmpty())
    {
        qDebug() << "Empty json document, exiting...";
        return 1008;
    }
    else
    {
        qDebug() << "Unable to determine type of JSON, exiting...";
        return 1009;
    }

    exit(1);
    return app.exec();
}

random.json

{
   "response":{
      "id":60491,
      "bytes":2042523,
      "created_at":"2012-06-23T01:31:26Z",
      "image":{
         "url":"http://a.desktopprassets.com/wallpapers/a61593e4a952def82666790770a7070c13726694/neptune.jpg",
         "thumb":{
            "url":"http://a.desktopprassets.com/wallpapers/a61593e4a952def82666790770a7070c13726694/thumb_neptune.jpg",
            "width":296,
            "height":185
         },
         "preview":{
            "url":"http://a.desktopprassets.com/wallpapers/a61593e4a952def82666790770a7070c13726694/preview_neptune.jpg",
            "width":960,
            "height":720
         }
      },
      "height":1200,
      "width":1600,
      "review_state":"safe",
      "uploader":"maybeso",
      "user_count":7,
      "palette":[
         "0C1219",
         "4266A1",
         "606469",
         "7595BC",
         "C1C7CD",
         "C2C7CD"
      ],
      "url":"https://www.desktoppr.co/wallpapers/60491"
   }
}

random.json file is json output get from Desktoppr API's random wallpaper function.

qtjson_qt5.cpp is a cpp file that demo the use of QJsonDocuments and related function is Qt5 to parse the JSON file