Parse json string to QMap

[Rua3n]

I'm not figuring out how to properly parse a JSON string and transform it into a QMap<QString, QString> my doubt relies on the part of checking if something is an array or object and recursively iterate it adding each value to its correspondent key/parent object.

The way I did the map is being constructed like this:

#include <QtCore/QCoreApplication>
#include <QJsonObject>
#include <QJsonDocument>
#include <QJsonArray>
    
void parseJsonObject(const QJsonObject &jsonObject, QMap<QString, QString> &map, const QString &parentKey = "")
{
    for(auto it = jsonObject.begin(); it != jsonObject.end(); ++it)
    {
        QString key = it.key();
        QJsonValue value = it.value();

        QString newKey = parentKey.isEmpty() ? key : parentKey + "." + key;

        if(value.isObject())
        {
            parseJsonObject(value.toObject(), map, newKey);
        }
        else if(value.isArray())
        {
            int index = 0;
            for(const QJsonValue &arrayValue : value.toArray())
            {
                if(arrayValue.isObject())
                {
                    parseJsonObject(arrayValue.toObject(), map, newKey + "." + QString::number(index));
                }
                else
                {
                    map.insert(newKey + "." + QString::number(index), arrayValue.toString());
                }
                index++;
            }
        }
        else
        {
            map.insert(newKey, value.toString());
        }
    }
}
    
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QString jsonString = R"({"files":{"App.exe":"f97611d3214dcb5146240c89a178b04a1e8100e870ec86468324aefc480d1946","D3Dcompiler_47.dll":"954ff81e19489b12645170aac2332a3f9829b66c626c164a47f983b05ba52f6c","generic":{"qtuiotouchplugin.dll":"ed725b71f5c6828762366686605e5a22bca1e66275a9a98c8d463a65f5eff4ff","test":{"xx.txt":""}},"iconengines":{"qsvgicon.dll":"02efd2585b646685b92322f1bca2cfd34282fab4ef9e10ea542e6acdedd867a3"},"imageformats":{"qgif.dll":"f73847dee80df1a80ac4442ec7d3feb5c865d6d2d4797c038c96196a4d24bda4","qicns.dll":"5fa7b0f2667ad3855f59422822e47e623a71e5c11067151213442b43091c47d3","qico.dll":"20b74e99dca0c80d3c9c2686a14184d1219edcb7294de8467e48a98d97399a13","qjpeg.dll":"d0b0af1a2a343546dcf737c74e3f11dcd665dd14c057ce46ea4784eeba7b8137","qsvg.dll":"c3c794214a18ceed47a6d30cb8784d2c0c9c3c2e41c1b397e9f99711e8173003","qtga.dll":"1121c5a2b59cef2d0c222f93481cfd16f0fd29c20768eb2bc77d9364392ca2f5","qtiff.dll":"27fa978a9a0db9c4fdc46a87675982fd8ae8727cad04f1542bcf426990817611","qwbmp.dll":"2c3769f6310ab957ef0825bfae204972c393c275819dbcc47f1dd8d3e58f2a56","qwebp.dll":"e916f1ef2938a59d8147b7da877d9b55a7dd4586b5f47d4ea8b844d276da6c98"},"networkinformation":{"qnetworklistmanager.dll":"980d0a553572f4e07ba959d7418c32a9dd8d698b8f107e2d5eae92ebf66e1373"},"platforms":{"qwindows.dll":"9ddfa666be52fe9b2fa1b5421a6d3d029eafe309bd971d0ab295c67da7bc6e14"},"Qt6Core.dll":"ba5e271f3052ff23e3d74a6462c93f54d6a11e08b3312a726992bf39b5160125","Qt6Gui.dll":"4995adb2bc21deaa123263638bc6fa0b504ac3a68e0bf7c7640caef6cfba0b71","Qt6Network.dll":"6f4a21e363a6d144eedeefb0b4c7726e036c1be3533487846748fadccc07801a","Qt6OpenGL.dll":"ebb6472d1c7c8b960aaf6492b51b841e527be9f6f9da51705a5fd6d537828e09","Qt6OpenGLWidgets.dll":"769d7906ceddd86d397bc4a1004833b3599e55cf978cf9c1f7d3ff0a8b32589d","Qt6RemoteObjects.dll":"c8c2aa99af3ee210cb8c560f655464132a8030d327a27774cec97a92f4a64b98","Qt6Svg.dll":"a21df38a3a8a4e9303cfd0823ce4bf234f1c676b84d896b94051c03873a146f0","Qt6UiTools.dll":"260d7526ca48905827101162ce030ffd5286a5cd8818191014516ef732432564","Qt6Widgets.dll":"e36a443c014c447fd325235292a4b0ad84c5ff4fbcbc78c6cdd76b393100e20b","Qt6Xml.dll":"ed307a0cc4629568509015cda6a545e32f294f21dd9f9be22ad1b8b191e703dd","styles":{"qwindowsvistastyle.dll":"16be061c545a0a9fd9444e776ab99c3353e24d99b7a6524b3343d72e3e64a220"},"tls":{"qcertonlybackend.dll":"9c919ec08a2b8ce2895d29b6e253765b5b0ccab23033f00d9bb345e2c3095e74","qopensslbackend.dll":"50079800b0c310a0b7cb249c4296932b3926dae2d8a3cc24c2be5ee87dc4070f","qschannelbackend.dll":"eeb4d3e5ee554c85da49caeb7e396dbc8c266506a7ae5431ddb5678cf60e5e04"},"translations":{}}})";
    QJsonDocument jsonDocument = QJsonDocument::fromJson(jsonString.toUtf8());
    if (!jsonDocument.isObject()) 
        qDebug() << "Invalid JSON format";

    QJsonObject jsonObject = jsonDocument.object();
    QMap<QString, QString> map;
    parseJsonObject(jsonObject, map);   
    return a.exec();
}

[SGaist]

Hi,

What exactly is your doubt ?

[Rua3n]

@SGaist how to properly construct the QMap from this json string.

[SGaist]

Ok, I see. Your main issue is that you are doing your work always in the same map. Once you have an object, you have to create a new map, fill it and then assign it to the current one. But ! You can't assign a QMap value to your QMap<QString, QString>. So your original plan can't work.

That's why QJsonObject as the toVariantMap function.

You have to change your design to work with QVariantMap.

[Rua3n]

@SGaist but im trying to build a QMap<Qstring, QString> not QVariant

[SGaist]

Then I may have misunderstood your current issue.

Can you show an example of the input you get and the output you expect to build from it ?

[Rua3n]

@SGaist

QMap<QString, QMap<QString, QMap<QString, QString>>> m = {
        {"files", {
            {"App.exe", {{"hash", "f976"}}},
            {"D3Dcompiler_47.dll", {{"hash", "954f"}}},
            {"generic", {
                {"qtuiotouchplugin.dll", {{"hash", "ed72"}}}, {"test", {{"hash", ""}}},
            }}
        }}
    };

There's another way to convert the json back to object/array?

[SGaist]

You can't dynamically create that kind of class in C++. However, if you have such a fixed known structure, then my remark about creating a new QMap each time you have to recurse.

[Rua3n]

@SGaist example please

[SGaist]

@Rua3n example of what ?

[SGaist]

I just realized something, based on what you want, you might want to check hlohmann json library. It might be better suited to your needs.

[JonB]

@SGaist
Blimey! From where I am/OP is now, I would just work with QJson and QVariantMap!

[SGaist]

@JonB said in Parse json string to QMap:

@SGaist
Blimey! From where I am/OP is now, I would just work with QJson and QVariantMap!

I already suggested that, but it seems not to be an option.

[JonB]

@SGaist
I know, I was agreeing with you :)

No idea how much JSON data OP has to parse. They might read it in as QVariantMap and transform in code to some specific QMap<..., ...> if demanded. Not the fastest, but might be quickest if OP wants to write it. Integrating the code you referenced has its own overheads :)