Key type of QJsonObject

tansgumus

Hi,

This is my fist time of using json under Qt.

I want to read any json file just like this js app but I don't know how to iterate QJsonObject correctly and how can I check the type of QJsonObject (object, element or array)

QJsonObject MainWindow::parser(QString fileName)
{
    QString val;
    QFile file;
    file.setFileName(fileName);
    file.open(QIODevice::ReadOnly | QIODevice::Text);
    val = file.readAll();
    file.close();

    QJsonDocument document = QJsonDocument::fromJson(val.toUtf8());
    QJsonObject object = document.object();

    QJsonObject::iterator i;
    for (i = object.begin(); i != object.end(); ++i) {
        if (i.value().isNull())
            qDebug() << i.key();
        else
            qDebug() << i.key() << i.value();
    }
}

The debuggers show whole json file content!

"FOOD PLAN" QJsonValue(object, QJsonObject({}))
"WORKOUT PLAN" QJsonValue(object, QJsonObject({"GYM":{},"HOME":{"DAY1":{},"DAY2":{"Exercise 1":{"Name":"name_vale","Narrator":"http://","Sets":{"12":"30 sec","3":"10 sec","5":"3 sec"},"Tip":"some tips","URL":"http://"},"Exercise 2":{},"Tip":"some tip"},"Tip":"some tip"}}))

A demo json for test:

{
	"WORKOUT PLAN": {
		"GYM": {},
		"HOME": {
			"DAY1": {},
			"DAY2": {
				"Exercise 1": {
					"Name": "name_vale",
					"URL": "http://",
					"Tip": "some tips",
					"Narrator": "http://",
					"Sets": {
						"3": "10 sec",
						"5": "3 sec",
						"12": "30 sec"
					}
				},
				"Exercise 2": {},
				"Tip": "some tip"
			},
			"Tip": "some tip"
		}
	},
	"FOOD PLAN": {}
}

SGaist

Hi,

QJsonValue provides several isXXX method to know what you are dealing with.

tansgumus

@SGaist said in Key type of QJsonObject:

Hi,

QJsonValue provides several isXXX method to know what you are dealing with.

Thanks a lot. But my code doesn't show the whole content of json file! It just shows the first objects!

QJsonObject MainWindow::parser(QString fileName)
{
    QString val;
    QFile file;
    file.setFileName(fileName);
    file.open(QIODevice::ReadOnly | QIODevice::Text);
    val = file.readAll();
    file.close();

    QJsonDocument document = QJsonDocument::fromJson(val.toUtf8());
    QJsonObject object = document.object();

    QJsonObject::iterator i;
    for (i = object.begin(); i != object.end(); ++i) {
        if (i.value().isObject()) {
            qDebug() << "OBJECT" << i.key();
        } else if (i.value().isArray()) {
            QString array_data;
            foreach (QVariant value, i.value().toArray().toVariantList()) {
                array_data += value.toString() + ", ";
            }
            qDebug() << "ARRAY" << array_data;
        } else {
            qDebug() << i.key() << i.value().toString();
        }

    }
}

What's wrong?!

log

OBJECT "FOOD PLAN"
OBJECT "WORKOUT PLAN"

JKSH

@tansgumus said in Key type of QJsonObject:

my code doesn't show the whole content of json file! It just shows the first objects!

An iterator only searches one "level". Your top-level object only has 2 members: "WORKOUT PLAN" and "FOOD PLAN".

You need to create a new QJsonObject::iterator for each "level". Something like this:

if (i.value().isObject()) {
    qDebug() << "OBJECT" << i.key();
    QJsonObject innerObject = i.value().toObject();
    QJsonObject::iterator j;
    for (j = innerObject.begin(); j != innerObject.end(); ++j) {
        if (j.value().isObject()) {
            qDebug() << '\t' << "OBJECT" << j.key();
            // ...
        }
        // ...
    }
}

Now, your output will be:

OBJECT "FOOD PLAN"
OBJECT "WORKOUT PLAN"
    OBJECT "GYM"
    OBJECT "HOME"

Of course, since your JSON document object has 6 levels, you should write recursive functions to process your whole document. Otherwise, your code will get too messy.

tansgumus

Thank you guys.

What a wonderful quick responses.