How can i write any data on directory

mrjj

Connect connect from a signal to a slot(function)

so here it says
When the manager say "finished" then call replyFinished located in "this" object

connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply*)));

and the slot / function us
void mainwindow::replyFinished(QNetworkReply *reply)

So all it does is to set up the connect for a signal and which function we want it to call.

so say we have 2 classes

A and B
A has beep signal and B have beepHandler
then we say
connect( pointer to a, beep , pointer to b, beephandler )
so beep goes to beephandler

For more info , please see
http://doc.qt.io/qt-5/signalsandslots.html

The version @Xiami is using just the same, but he uses the new syntax and
uses a lambda which is a c++ things that allows you to define functions in place/right there.
connect(reply,&QNetworkReply::finished,this,[&] { this is your slot }

Armin

@mrjj Thanks
Why in this example you have pointed to class?

mrjj

@Armin
because connects wants the address of a real objects.
like in
ClassX * inst= new ClassX;
inst is the right kind for connect.
Its a instance of the type/class ClassX;

Its not for all ClassX created, but only
for those you connect.

Armin

@mrjj I feel, your code is hard and twisted , so can you make it simpler for me?

VRonin

@Armin said in How can i write any data on directory:

your code is hard and twisted

No it's not, I wouldn't know how to make it easier. You should probably take a look at http://doc.qt.io/qt-5/signalsandslots.html

@Xiami

no need to use the "controversial" sender() here, just pass reply by value in the capturing group of the lambda
do not use C-cast to downcast, it's unsafe, use dynamic_cast or, if it's a QObject as it's always the case when calling sender(), qobject_cast
if the downloaded file is too big you might run out of memory if you wait for finished do the processing as soon as there is data available using readyRead

QFile* file=new QFile("DownloadResult.dat"); //the file to save the data into
if(file->open(QIODevice::WriteOnly)){ //if you can open the file for writing
    QNetworkAccessManager *netaccessmanager = new QNetworkAccessManager; //create the manager
    QNetworkReply* reply = netaccessmanager.get(QNetworkRequest(QUrl(ui->textEdit->toPlainText()))); // send the request
    connect(reply,&QNetworkReply::readyRead,this,[reply,file]()->void{ //when there is data available
        file->write(reply->readAll()); //save it to file
    });
    connect(reply,&QNetworkReply::finished,reply,&QNetworkReply::deleteLater); //when finished clear the memory
    connect(netaccessmanager,&QNetworkAccessManager::finished,reply,&QNetworkAccessManager::deleteLater); //when finished clear the memory
    connect(reply,&QNetworkReply::finished,file,&QFile::deleteLater);//when finished close the file and clear the memory
}

Armin

@mrjj said in How can i write any data on directory:

connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply*)));
manager->get(QNetworkRequest(QUrl("http://www.google.com")));

why connect is on 5 line ?
shouldn't be on 4 line?

mrjj

@Armin
Hi
well its just important to connect it up before starting to use it.
So best spot is usual when you create it.

Armin

@mrjj
Can i use code in below?

QNetworkRequest request;
request.setUrl(QUrl("http://qt-project.org"));
request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");

QNetworkReply *reply = manager->get(request);
connect(reply, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));

mrjj

@Armin
Yes looks fine :)

Armin

@mrjj said in How can i write any data on directory:

1 - it will send a signal when something is read (replyFinished) or error happened.

I get this message :
QObject::connect: No such signal QNetworkAccessManager::finished(*QNetworkReply) in ..\DownloadManager\mainwindow.cpp:20
QObject::connect: (receiver name: 'MainWindow')

why?

mrjj

show the actual real code
it says QNetworkAccessManager dont have finished signal but syntax looks wrong

QNetworkAccessManager::finished(*QNetworkReply) <<< the * seems very wrong