How should i store the results ??

Qjay

Hello i have a simple Qprocess program which calls meson and returns results in JSON .
[{"name": "myexe", "installed": false, "id": "myexe@exe", "filename": "myexe", "type": "executable", "build_by_default": true}]

QCoreApplication a(argc, argv);
    QObject *parent = nullptr;
    QProcess *process = new QProcess(parent);
    const QString program  = "/usr/local/bin/meson";
    const QStringList args = {"introspect", "--targets", "/home/user/meson/builddir/"};
  
    process->start(program, args);
    int res = process->waitForFinished();

    if ( !res ) {
        qDebug() << process->errorString();

    }
    process->waitForFinished();
    QByteArray output = process->readAllStandardOutput();
    qDebug() << "output : " << output << "\n";

It returns a QByteArray , how can i save it in json or something similar where i can extract each element

i tried like this :

JsonDocument item = QJsonDocument::fromJson(output);
    qDebug() << "item : " << item << "\n";
    QJsonArray rootobj = item.array();
    qDebug() << "rootobj : " << rootobj << "\n";

but i am not able to access individual element .

Paul Colby

Hi @Qjay,

but i am not able to access individual element .

Here's a basic example:

const QByteArray output("[{\"name\": \"myexe\", \"installed\": false, \"id\": \"myexe@exe\", \"filename\": \"myexe\", \"type\": \"executable\", \"build_by_default\": true}]");
qDebug().noquote() << output;

const QJsonDocument doc = QJsonDocument::fromJson(output);
qDebug().noquote() << doc;
qDebug().noquote() << doc.array();
qDebug().noquote() << doc.array().first();
qDebug().noquote() << doc.array().first().toObject();
qDebug().noquote() << doc.array().first().toObject().value("name");
qDebug().noquote() << doc.array().first().toObject().value("name").toString();
qDebug().noquote() << doc.array().first().toObject().value("installed");
qDebug().noquote() << doc.array().first().toObject().value("installed").toBool();

The output:

[{"name": "myexe", "installed": false, "id": "myexe@exe", "filename": "myexe", "type": "executable", "build_by_default": true}]
QJsonDocument([{"build_by_default":true,"filename":"myexe","id":"myexe@exe","installed":false,"name":"myexe","type":"executable"}])
QJsonArray([{"build_by_default":true,"filename":"myexe","id":"myexe@exe","installed":false,"name":"myexe","type":"executable"}])
QJsonValue(object, QJsonObject({"build_by_default":true,"filename":"myexe","id":"myexe@exe","installed":false,"name":"myexe","type":"executable"}))
QJsonObject({"build_by_default":true,"filename":"myexe","id":"myexe@exe","installed":false,"name":"myexe","type":"executable"})
QJsonValue(string, myexe)
myexe
QJsonValue(bool, false)
false

Above, I used .first() since the JSON array only has one item, but if you expected any number of items, you can loop through it like:

const QJsonDocument doc = QJsonDocument::fromJson(output);
qDebug().noquote() << doc;
qDebug().noquote() << doc.array();
foreach (auto value, doc.array()) {
    qDebug().noquote() << value;
    qDebug().noquote() << value.toObject();
    qDebug().noquote() << value.toObject().value("name");
    qDebug().noquote() << value.toObject().value("name").toString();
    qDebug().noquote() << value.toObject().value("installed");
    qDebug().noquote() << value.toObject().value("installed").toBool();
}

(same output)

Cheers.

Qjay

@Paul-Colby said in How should i store the results ??:

qDebug().noquote() << doc;
qDebug().noquote() << doc.array();
foreach (auto value, doc.array()) {
qDebug().noquote() << value;
qDebug().noquote() << value.toObject();
qDebug().noquote() << value.toObject().value("name");
qDebug().noquote() << value.toObject().value("name").toString();
qDebug().noquote() << value.toObject().value("installed");
qDebug().noquote() << value.toObject().value("installed").toBool();
}

Thanks , exactly what i was looking for :)

Qjay

@Paul-Colby how can i store the results as QVariantMap ?

Paul Colby

Hi @Qjay,

@Paul-Colby how can i store the results as QVariantMap ?

Since the document is an array, you should convert it to a QVariantList rather than QVariantMap, otherwise, you can convert individual entries to QVariantMap objects. Here's a quick example of both:

const QByteArray output("[{\"name\": \"myexe\", \"installed\": false, \"id\": \"myexe@exe\", \"filename\": \"myexe\", \"type\": \"executable\", \"build_by_default\": true}]");
qDebug().noquote() << "bytes" << output;

const QJsonDocument doc = QJsonDocument::fromJson(output);
qDebug().noquote() << "doc:" << doc;
qDebug().noquote() << "list:" << doc.array().toVariantList();
foreach (auto value, doc.array()) {
    qDebug() << "map:" << value.toObject().toVariantMap();
}

Output:

bytes [{"name": "myexe", "installed": false, "id": "myexe@exe", "filename": "myexe", "type": "executable", "build_by_default": true}]
doc: QJsonDocument([{"build_by_default":true,"filename":"myexe","id":"myexe@exe","installed":false,"name":"myexe","type":"executable"}])
list: (QVariant(QVariantMap, QMap((build_by_default, QVariant(bool, true))(filename, QVariant(QString, myexe))(id, QVariant(QString, myexe@exe))(installed, QVariant(bool, false))(name, QVariant(QString, myexe))(type, QVariant(QString, executable)))))
map: QMap(("build_by_default", QVariant(bool, true))("filename", QVariant(QString, "myexe"))("id", QVariant(QString, "myexe@exe"))("installed", QVariant(bool, false))("name", QVariant(QString, "myexe"))("type", QVariant(QString, "executable")))

Cheers.

Qjay

@Paul-Colby Thanks

i myself did something like this :)

 QVariantMap json_map;


    const QJsonDocument doc = QJsonDocument::fromJson(output);
    qDebug().noquote() << doc;
    qDebug().noquote() << doc.array();
    foreach (auto value, doc.array()) {
        qDebug().noquote() << value;
        qDebug().noquote() << value.toObject();
        qDebug().noquote() << value.toObject().value("name");
        json_map["name"] = value.toObject().value("name").toString();

        json_map["installed"] = value.toObject().value("installed").toBool();

        json_map["id"] = value.toObject().value("id").toString();

     
        json_map["filename"] = value.toObject().value("filename").toString();



    }