where is QJsonObject

MasterQ

Hello,

where do I find QJsonObject in PySide6?

from PySide6.QtCore import QJsonDocument, QJsonObject
print(PySide6.__version__)
a = QJsonDocument()
b = QJsonObject()

6.8.0.2

ImportError: cannot import name 'QJsonObject' from 'PySide6.QtCore'

According to the documentation QJsonObject is located in QtCore as QJsonDocument, QJsonArray, QJsonValue. But it is not found.

C++ is working:

#include <QCoreApplication>
#include <QDebug>

#include <QJsonObject>

int main(int argc, char *argv[]) {
    QCoreApplication app(argc, argv);
    auto a = new QJsonObject();
    qDebug() << a;
}

0x55e154300560

JonB

@MasterQ
Nope, in the sense of Qt XML C++ Classes

Note: Qt XML will no longer receive additional features. For reading or writing XML documents iteratively (SAX), use the QXmlStreamReader and QXmlStreamWriter classes. The classes are both easier to use and more compliant with the XML standard.

They are removing high-level support, you have to use low-level calls and roll your own higher level stuff.

XML can create complex "documents", but is heavier weight. IMHO JSON barely creates a "document", it just saves/restores arrays and objects of a few base types in a limited structure. Which is fine if that's all you want.

Again, I don't think Qt libraries themselves use either JSON or XML so it's really for your internal use and from Python you can use its own support for these if you want more than Qt offers.

JonB

@MasterQ
Answer in two parts.

Documentation notwithstanding, I think you will find there is no such Python/PySide/PyQt type as QJsonObject. In Python this is just a dictionary of key-values, dict_keys, and that is what will be returned and you should use. Similarly I imagine QJsonArray will be a Python array.

However, when I try to test it I get no further with the following code snippet:

from PySide6.QtCore import QCoreApplication, QJsonDocument
app = QCoreApplication([])
a = QJsonDocument()
doc = QJsonDocument.fromJson(b"{ 'key1': '0' }")
print(doc, doc.isObject(), doc.isEmpty(), doc.toJson())
obj = doc.object()
print(obj)
print(obj.keys())
print(obj['key1'])

This shows QJsonDocument.fromJson(b"{ 'key1': '0' }") produces an empty document which, unless I am going mad, is not right, I believe that is correct JSON and should produce a document with an object with a key1 key, but it doesn't. Nor in PyQt6. So I am a bit lost. If anyone would care to show me what i am doing wrong here that would be great! [EDIT See post later on.]

Since so far as I know Qt does not actually use its QJson classes for anything internally you may find that using Python's own support for JSON is just as useful/better than using the Qt classes (which i appear to have trouble getting working).

MasterQ

Is the Qt support for XML better?

I haven't made up my mind yet and maybe XML could be a better choice, even if Pythons native JSON support is very handy.

XML, in general, seems much more complex as JSON in creating "documents".

JonB

@MasterQ
Nope, in the sense of Qt XML C++ Classes

Note: Qt XML will no longer receive additional features. For reading or writing XML documents iteratively (SAX), use the QXmlStreamReader and QXmlStreamWriter classes. The classes are both easier to use and more compliant with the XML standard.

They are removing high-level support, you have to use low-level calls and roll your own higher level stuff.

XML can create complex "documents", but is heavier weight. IMHO JSON barely creates a "document", it just saves/restores arrays and objects of a few base types in a limited structure. Which is fine if that's all you want.

Again, I don't think Qt libraries themselves use either JSON or XML so it's really for your internal use and from Python you can use its own support for these if you want more than Qt offers.

JonB

@MasterQ
FWIW, thanks to @J-Hilk corrected my attempted example so it actually works, I forgot JSON insists on double-quotes not single-quotes:

from PySide6.QtCore import QCoreApplication, QJsonDocument, QJsonParseError
app = QCoreApplication([])
a = QJsonDocument()
err = QJsonParseError()
doc = QJsonDocument.fromJson(b'{ "key1": 0 }', err)
print(doc, doc.isObject(), doc.isEmpty(), doc.toJson(), err.errorString())
obj = doc.object()
print(obj)
print(obj.keys())
print(obj['key1'])

Pl45m4

@MasterQ said in where is QJsonObject:

C++ is working

Of course it is ;-)

Jokes aside, if you don't want to use the "native" Python types as suggested by @JonB, why not use C++ directly?

MasterQ

native Python types are fully OK. I just wanted to test, what is better, native Python or Qt.

JonB

Like I said, Qt's support for JSON or XML is not as comprehensive as Python's, and you can afford to use the latter in a Qt Python program if you want better support.