CODEWITHSUNDEEP
c++qt
BD_Mamun
BD_Mamun

Reputation: 3

Application crashes when using global QNetworkCookieJar for multiple windows

I am new at Qt and using Qt5.5 to create a http client application which will load a window with a fixed URL. After login in this window the other windows of same site should get the same session. At this purpose I have used global pointer jar of QNetworkCookieJar class and implemented on the following code for every window

Window1::Window1(QWidget *parent) :
QWidget(parent),
ui(new Ui::Window1)
{
    ui->setupUi(this);
    QUrl webURL("http://someURL");
    ui->webView->show();
    ui->webView->load(webURL);

    ui->webView->page()->networkAccessManager()->setCookieJar(jar);
}

It solves the multiple authentication problem, but when I close any window and reopen it instantly it causes appcrash.

Please give me a suggestion on my problem. Thanks in advance.

Upvotes: 0

Views: 117

Answers (2)

BD_Mamun
BD_Mamun

Reputation: 3

Thanks ThorngardSO.. I have found a solution using your answer. Here is my solution,

if(jar.isNull()==true){
    qDebug()<<"object null";
    QPointer <QNetworkCookieJar> jar_new = new QNetworkCookieJar(0);
    ui->webView->page()->networkAccessManager()->setCookieJar(jar_new);
    jar=jar_new;
}
else
    ui->webView->page()->networkAccessManager()->setCookieJar(jar);

Upvotes: 0

ThorngardSO
ThorngardSO

Reputation: 1211

From the Qt5 docs (http://doc.qt.io/qt-5/qnetworkaccessmanager.html#setCookieJar):

Note: QNetworkAccessManager takes ownership of the cookieJar object.

So the accessmanager will delete your jar instance. There might be your problem! I don't know enough about the webview/page/accessmanager to be sure about the lifetime of the manager, but it seems to be bound to the webview/your ui, so when it's closed+destroyed, your cookiejar will have gone, too.

As QNetworkCookieJar inherits from QObject, you might want to use a guarded QPointer<QNetworkCookieJar> jar instead of a simple QNetworkCookieJar* jar variable. Then, you will notice that your guarded pointer becomes null after the first window is closed/destroyed. That would a) verify my claim from the last paragraph and b) guard you against stale pointer accesses in the future (in fact, your program would no longer crash).

Upvotes: 1

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