CODEWITHSUNDEEP
phpweb-servicesqthttpxdebug
Horst Walter
Horst Walter

Reputation: 14081

Qt to PHP post request truncated at 1024 characters - why?

I sent a Qt JSON string > 1024 charaters to PHP (tested both, via multi part and url encoding).

    QHttpMultiPart *multiPart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
    QHttpPart textPart;
    textPart.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"swiftjson\""));
    textPart.setBody(QJsonDocument(model.toJson()).toJson(QJsonDocument::Compact));
    multiPart->append(textPart);

On the PHP side the JSON string is truncated at 1024 characters for some reason

String truncated at 1024

I have tested:

  1. The string on client side is OK and longer than 1024 characters
  2. I have used a QUrlQueryinstead of multipart, same situation
  3. PHP: post_max_size 20M

Looking for a hint how I can send > 1024 characters

Upvotes: 3

Views: 568

Answers (2)

Horst Walter
Horst Walter

Reputation: 14081

I have figured it out. It is actually the debugger truncating the variables, or more precisely the display is truncated. The actual value is untouched, but I was mislead by the display. Setting the value to 2048 for the debugger solves the issue.

Actually the value in brackets (above screenshot) is the real size, which I thought is the byte size. Once you know ...

Thanks to all who helped.

Elcipse Debugger

Upvotes: 0

phyatt
phyatt

Reputation: 19112

You probably have to use waitForBytesWritten with some sort of loop, or use the related signal: bytesWritten.

http://doc.qt.io/qt-5/qabstractsocket.html#waitForBytesWritten

http://doc.qt.io/qt-5/qiodevice.html#bytesWritten

The loopback example shows how to send a large payload in a response properly.

http://doc.qt.io/qt-5/qtnetwork-loopback-dialog-cpp.html

static const int PayloadSize = 64 * 1024; // 64 KB
static const int TotalBytes = 50 * 1024 * 1024;


connect(&tcpClient, SIGNAL(bytesWritten(qint64)),
            this, SLOT(updateClientProgress(qint64)));

// called when the TCP client connected to the loopback server
bytesToWrite = TotalBytes - (int)tcpClient.write(QByteArray(PayloadSize, '@'));

...

void Dialog::updateClientProgress(qint64 numBytes)
{
    // callen when the TCP client has written some bytes

    // ...

    // only write more if not finished and when the Qt write buffer is below a certain size.
    if (bytesToWrite > 0 && tcpClient.bytesToWrite() <= 4*PayloadSize)
        bytesToWrite -= (int)tcpClient.write(QByteArray(qMin(bytesToWrite, PayloadSize), '@'));

    // ...
}

Hope that helps.

Upvotes: 2

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