QNetworkAccessManager - How to send "PATCH" request

Question

I am trying to send a "PATCH" request to my firebase application.As far as I read QNetworkManager doesn't support "Patch" request.

How can I send "PATCH" request ?

Precipitant

Answer 1

So we are clear that there is no method in QNetworkAccessManager named "patch" Therefore I have used "sendCustomRequest" but with QBuffer. Because QNetworkManager requires a QIODevice object.

QString destination="";
currentNode.replace(QString("/").append(latestNode),"");
destination
        .append(host)
        .append(currentNode)
        .append(".json");
QString jsonString=QString(QString("{").append("\"").append(latestNode).append("\"").append(":").append("\"").append(str).append("\"").append(QString("}")));
QNetworkRequest request(destination);
request.setHeader(QNetworkRequest::ContentTypeHeader,
    "application/x-www-form-urlencoded");
qDebug()<<jsonString;
QBuffer *buffer=new QBuffer();
buffer->open((QBuffer::ReadWrite));
buffer->write(jsonString.toUtf8());
buffer->seek(0);
manager->sendCustomRequest(request,"PATCH",buffer);
qDebug()<<"posted";

Precipitant

Aside: using operator + instead of all those appends results in clearer and more maintainable code. – Valance

Note that the QBuffer needs to be created as a pointer (as Aykut rightly did) and not on the stack, otherwise it might be garbage collected before the request has time to be executed, leading to very hard to debug issues. – Redoubt

If you want to use QBuffer, you can make the code simpler (as per Qt source code for QNetworkAccessManager) and replace the calls to write & seek with setData(). However QNetworkAccessManager::sendCustomRequest() has a variant that takes a QByteArray, so you could bypass QBuffer and simply put manager->sendCustomRequest(request,"PATCH",jsonString.toUtf8()); – Eckhart

Answer 2

try:

QNetworkAccessManager* manager = new QNetworkAccessManager();
QNetworkRequest request("http://<domain>/<path>/");
QHttpMultiPart* multipart = new QHttpMultiPart();
//... Add your data in multipart
manager->sendCustomRequest(request, "PATCH", multipart);

Cumings

Answer 3

As QNetworkAccessManager does not support PATCH implicitly, I've created the following class QNetworkAccessManagerWithPatch that does. Use it in place of QNetworkAccessManager and you'll have the same 3 variants for patch() as there are for post(), put(), etc.

Get the Github gist here: https://gist.github.com/paulmasri/efafb8ee350a8ce84a6657a30eb4eb8a

Or take the code directly from here: (save as QNetworkAccessManagerWithPatch.h)

#pragma once

#include <QNetworkAccessManager>

class QNetworkAccessManagerWithPatch : public QNetworkAccessManager
{
    Q_OBJECT

public:
    explicit QNetworkAccessManagerWithPatch(QObject *parent = Q_NULLPTR)
        : QNetworkAccessManager(parent) {}

    QNetworkReply* patch(const QNetworkRequest &request, QIODevice *data)
    { return sendCustomRequest(request, "PATCH", data); }
    QNetworkReply* patch(const QNetworkRequest &request, const QByteArray &data)
    { return sendCustomRequest(request, "PATCH", data); }

#if QT_CONFIG(http)
    QNetworkReply *patch(const QNetworkRequest &request, QHttpMultiPart *multiPart)
    { return sendCustomRequest(request, "PATCH", multiPart); }
#endif
};

Eckhart

While the point of stack overflow is not to get free code, I like it when you are in the middle of building a solution and is blocked by an distracting issue with the framework (or whatever), and then... suddenly a heavenly developer shares you some code that allows you to focus on the actual solution you were working on.... Thanks mate. – Ravin