How can I get things from website

victor wang

Hi, i'm using Qt5.5 on my computer.
I have the website here
http://www1.winmate/PLMS/TestCheck.asp?LSN=201503003009&EmpId=we9999&CPID=TOUCH&CPKey=Pass

It will show "update ok".
This is my code now. here

I can't get anything from there.
Did i miss something or need to fix?
Please Help!

jsulm

@victor-wang You have no error handling at all!
Connect http://doc.qt.io/qt-5/qnetworkreply.html#error-1 to a slot and print the error message.

victor wang

@jsulm
You mean to add like this ?

qDebug()<<QNetworkReply::errorString

But actually it will got error said "cannot call member function 'QString QIODevice::errorString() const" without object "

what do i need to fix?

J.Hilk

@victor-wang

you give it an object, obviously :-)

use this and show us the error msg:

QNetworkRequest request;
request.setUrl(QUrl("...."));

QNetworkReply *reply = manager->get(request);
connect(reply, &QNetworkReply::error, [=](QNetworkReply::NetworkError err){
qDebug() << err;});

victor wang

@J.Hilk

I got this error here
no matching function.

VRonin

@victor-wang You just need to open the docs to find the solution: http://doc.qt.io/qt-5/qnetworkreply.html#error-1 instead of &QNetworkReply::error use static_cast<void(QNetworkReply::*)(QNetworkReply::NetworkError)>(&QNetworkReply::error) or QOverload<(QNetworkReply::NetworkError)>::(&QNetworkReply::error)>

J.Hilk

@victor-wang
My bad, QNetworkReply::error is an overloaded function.

use this:

connect(networkReply, static_cast<void(QNetworkReply::*)(QNetworkReply::NetworkError)>(&QNetworkReply::error),
    [=](QNetworkReply::NetworkError code){ qDebug() << code; });

taken from the docu

JKSH

@J.Hilk said in How can I get things from website:

connect(networkReply, static_cast<void(QNetworkReply::*)(QNetworkReply::NetworkError)>(&QNetworkReply::error),
    [=](QNetworkReply::NetworkError code){ qDebug() << code; });

taken from the docu

In Qt 5.7 onwards, you can also use qOverload() (with C++14) or QOverload (C++11), instead of the longer static_cast: http://doc.qt.io/qt-5/qtglobal.html#qOverload

connect(networkReply, qOverload<QNetworkReply::NetworkError>(&QNetworkReply::error),
    [=](QNetworkReply::NetworkError code) { qDebug() << code; });

victor wang

@JKSH @J-Hilk
I'm using Qt5.5 so i can't use qOverload on my Qt version.
I had changed it but it still got error.
This is my code here

And this is the error that i got here

It's the same error shows no matching function for call.
What else should i do ?

JKSH

@victor-wang said in How can I get things from website:

And this is the error that i got here

You have a warning message: "lambda expressions only available with -std=c++11 or -std=gnu++11"

That means haven't enabled C++11.

Add this line to your *.pro file to enable it: CONFIG += C++11

victor wang

@JKSH
I can compiled it successfully.
But i don't know what this is doing ?
I still can't get any information from my Url.

This is my code here

And this is what i got here

I didn't get any error back but also didn't get what i want back either.

This is the Url i want to get http://192.168.100.59/PLMS/TestCheck.asp?LSN=201503003009&EmpId=we9999&CPID=OS&CPKey=95Z0000000AF

I should get a file or get a respond that said ok.

JKSH

Please post your code as text, not pictures. Text is much easier to read and search.

Anyway, what is inside your replyFinished() function?

victor wang

@JKSH

void MainWindow::replyFinished(QNetworkReply *reply)
{
qDebug("connect content");
QTextCodec *codec=QTextCodec::codecForLocale();
int connect_url=reply -> attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
qDebug()<<connect_url;
qDebug("here");

}

Sorry, i'm using Qt via Xming and i can't just copy the code to my local computer.
I have to type myself.

For the picture i just gave you.
"connect_url" will print the number 200 out to make sure the Url is connecting successfully.

JKSH

@victor-wang said in How can I get things from website:

"connect_url" will print the number 200 out to make sure the Url is connecting successfully.

Yes, 200 means "HTTP OK": http://www.restapitutorial.com/httpstatuscodes.html

Your code is connecting to the server OK.

void MainWindow::replyFinished(QNetworkReply *reply)
{
qDebug("connect content");
QTextCodec *codec=QTextCodec::codecForLocale();
int connect_url=reply -> attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
qDebug()<<connect_url;
qDebug("here");

}

You need to read the data from the QNetworkReply. Call reply->readAll() to get the data.

Also, remember to delete your QNetworkReply after you have finished, or else you will have a memory leak. See the QNetworkReply documentation: http://doc.qt.io/qt-5/qnetworkreply.html

@victor-wang said in [How can I get things from website](/topic/77075/how-can-i-get-things-from-

I should get a file

As I said above, you must call reply->readAll() to get the data. Then, write the data into a file using a QFile.

victor wang

@JKSH
you mean i have to add this after the connect function?

qDebug()<<reply->readAll();
reply->deleteLater();

Is that readAll will print the information out?
Or i have to using qDebug to print it out?

JKSH

@victor-wang said in How can I get things from website:

@JKSH
you mean i have to add this after the connect function?
qDebug()<<reply->readAll();
reply->deleteLater();

I mean you have to add this inside your replyFinished() slot.

Are you familiar with asynchronous programming? Networking is asynchronous. When you call QNetworkAccessManager::get(), it starts downloading. However, it doesn't wait for the download to finish. Instead, QNetworkAccessManager and QNetworkReply WILL emit the finished() signal when the download finishes. So, you can read the downloaded data from inside the connected slot.

Is that readAll will print the information out?
Or i have to using qDebug to print it out?

readAll() gives you the data in a QByteArray. It doesn't print anything. Do you know how to use QByteArray?

qDebug prints to the console.

victor wang

@JKSH

I am not quite sure that i'm using the right way.
I write this code into replyFinished();

QByteArray output;
output = reply -> readAll();
qDebug()<<output;
reply->deleteLater();

Am i right?
Sorry i'm new in Qt please be patient to me:(

JKSH

@victor-wang said in How can I get things from website:

I write this code into replyFinished();
QByteArray output;
output = reply -> readAll();
qDebug()<<output;
reply->deleteLater();
Am i right?

Yes, that is right :)

Now, you can save output into a file, using QFile.

Sorry i'm new in Qt please be patient to me:(

No problem! We are happy to help beginners. I think you are learning well.

victor wang

@JKSH
I this function will show the content out?

qDebug()<<output;

If it is why it showed NULL on the console. here
I thought it will print the Url information which i had just gave you "Updated ok!".

victor wang

@victor-wang

I add this after connect instead of replyFinished slot.

file.setFileName("/home/check.txt");
if(!file.exist)qDebug("not exist");
if(!file.open(QIODevice::WriteOny | QIODevice::Text))qDebug("not write success");
stream.setDevice(&file);
stream<<out;
file.close;

But when i went to cat the check.txt there is nothing in the file.

And i add this in my replyFinished slot.

out=reply->readAll();
qDebug()<<out;
reply->deleteLater();

The "QByteArray out" i had declared it in the mainwidow.h for global type.
Did i need to put in the private place or the public place in the mainwindow.h?

Why i still didn't see anything in my file?