reading from NetworkReply always give incomplete string of data

Ragbot

void WebApi::readReady()
{
    QFile file("response.json");
    file.open(QIODevice::WriteOnly);
    QTextStream stream(&file);
    stream << reply->readAll();
    qDebug() << reply->readAll();
    stream.flush();
}

This code always results in such a response

// A lot more data here but still cutoff
-87dd-415e-bbc0-2ec27bf404cc",
        "type": "tag",
        "attributes": {
            "name": {
                "en": "Fantasy"
            },
            "description": {},
            "group": "genre",
            "version": 1
        },
        "relationships": []
    }
],
"state": "published",
"chapterNumbersResetOnNewVolume": false,
"createdAt": "2019-02-09T21: 22: 51+00: 00",
"updatedAt": "2023-03-10T19: 04: 19+00: 00",
"version": 8,
"availableTranslatedLanguages": [
    "en",
    "cs",
    "ru"
],
"latestUploadedChapter": "f729402f-5d8f-4bb4-832a-842e0fa4da9e"
},
"relationships": [
{
    "id": "43fa8935-9025-4f35-afb6-ba64e7883fa2",
    "type": "author"
},
{
    "id": "43fa8935-9025-4f35-afb6-ba64e7883fa2",
    "type": "artist"
},
{
    "id": "81af78b3-9a6c-4fb9-8add-348b92275b9e",
    "type": "cover_art"
}
]
}
],
"limit": 10,
"offset": 0,
"total": 2
}

why is it so?
where am i going wrong?

JonB

@Ragbot
This issue is not to do with design, and belongs in the General forum.

You cannot just call reply->readAll() and expect it to return something at the instant called. You need to attach a slot for when data arrives. And your data may well arrive in multiple "chunks", not all in one call, so the signal/slot may be called multiple times. If readReady() is a slot (who knows?) it needs to allow to be called several times, e.g. it can't just overwrite an output file.

Also do not call qDebug() << reply->readAll();, that would do a new read, which I doubt you intend.

Ragbot

@JonB Thanks I didn't mean to publish it to the design section sorry.

and yes it is connected via

    reply = client.get(QNetworkRequest(QUrl(base_url + page)));
    connect(reply, &QNetworkReply::readyRead, this, &MangaDex::readReady);

and I do understand the chunking concept but I am not sure how to finish writing those chunks so I don't just keep appending to the previous response.

How do handle this I?
Is there a way to know when it is finished?
if so how do I use it in this context?

jsulm

@Ragbot said in reading from NetworkReply always give incomplete string of data:

how to finish writing those chunks so I don't just keep appending to the previous response

You need some kind of protocol, so you know when you received a whole package...

Ragbot

@jsulm What does that mean?
I don't own the api so I am not sure, does it have something to do with that?

also can I just connect QNetworkReply::finished to write the data to file while readReady reads to buffer?

JonB

@Ragbot
Yes, assuming what you are getting is just JSON content, see void QNetworkReply::finished(). You can also do a readAll() there to read and save reply in one call. Presumably Ok unless package data is huge. Try just moving your readReady() to that signal?

Bob64

This post is deleted!