Can't read file more than n bytes

metaDom

Hey guys,

I'm trying to parse a json file, however for some unknown reason it fails to read it completely. I can read 29276 bytes, then it suddenly stops. It doesn't matter if I try to save the content as QByteArray or QString. The qDebug() line is simply not executed, all code after works...

http://pastebin.com/raw/eQ9v0AyT

QFile dataFile("data.json");
if(dataFile.open(QIODevice::ReadOnly))
{
	QByteArray ba = dataFile.readAll();
	qDebug() << "File Content: " << ba;
	dataFile.close();
}

Any help is appreciated. Thanks in advance!

m.sue

Hi,
maybe qDebug() << ba; just doesn't show it all. Can you try qDebug() << ba.count();
-Michael.

metaDom

@m.sue dataFile.count() or dataFile.size() etc do work fine. What doesn't work is outputting the ba itself or stuff like ba.trimmed()

m.sue

Yes, but my point is about what it is that does not work: The reading itself or the output of the read-in bytearray via qDebug.
Please add the line:

qDebug() << ba.count();

-Michael.

metaDom

@m.sue sorry, typo. didn't mean dataFile.count(). "qDebug() << ba.count();" does work fine and give proper output.

When reading more than my limit, for example with "QByteArray ba = dataFile.read(29277)", ba.count() also does work. So yes, the reading works.

Adding the following returns "true". So the doc is also empty when using the ByteArray.

QJsonDocument doc = QJsonDocument::fromJson(ba);
                qDebug() << doc.isEmpty();

m.sue

That may be restriction in the buffer length of the (place where you view the) qDebug output.
Maybe just view it in two parts will show you the results:

qDebug() << ba.right(25000);
qDebug() << ba.mid(25000);    //+/- 1

metaDom

@m.sue said in Can't read file more than n bytes:

That may be restriction in the buffer length of the (place where you view the) qDebug output.
Maybe just view it in two parts will show you the results:
qDebug() << ba.right(25000);
qDebug() << ba.mid(25000);    //+/- 1

This actually works for output. I've used:

                qDebug() << "AAA";
                qDebug() << ba.left(dataFile.size()/2);
                qDebug() << "BBB";
                qDebug() << ba.right(dataFile.size()/2);
                qDebug() << "CCC";

Anyway, the buffer also seems to be there when doing:

QJsonDocument doc = QJsonDocument::fromJson(ba);

If I split the file, the json is invalid and can't be put with fromJson anymore. This seems to be a very weird limitation?!

raspe88

Have you tried the following steps to get a valid document:

Allocate a char-array of the size you need.
Copy the file-content using QTextStream to this array.
Get a valid QJsonDocument by using QJsonDocument::fromRawData

jsulm

@metaDom I think it is a limitation of qDebug: it just stops at some point to not to print too much. You can try to print with std::cout << ba;

SGaist

Hi,

Do you have any special character in your .json file ?

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Can't read file more than n bytes