How to use QWebEngine to intercept HTML get the post data?

mouse

In QtWebKit we can use QNetworkAccessManager, like:```
//code
class NetworkAccessManager : public QNetworkAccessManager
{
public:
explicit NetworkAccessManager(QNetworkAccessManager *manager, QObject *parent);
protected:
QNetworkReply * createRequest(QNetworkAccessManager::Operation operation,const QNetworkRequest &request, QIODevice *device);
};

We can implement QNetworkReply * createRequest(). In this method we can get:
operation (QNetworkAccessManager::Operation operation)
request (const QNetworkRequest &request)
post data (QIODevice *device)
From request we can get the url, from post data  we can get  data from html (maybe other operation also have this data).

In QtWebEngine we can use QWebEngineUrlRequestInterceptor to get operation and url, like:```
//code
class WebUrlRequestInterceptor : public QWebEngineUrlRequestInterceptor
{
public:
    WebUrlRequestInterceptor(QObject *p = Q_NULLPTR);
    void interceptRequest(QWebEngineUrlRequestInfo &info);
    ~WebUrlRequestInterceptor();
};

We can implement interceptRequest(QWebEngineUrlRequestInfo &info), in this method we have info, from info we can get
operation (info.requestMethod)
url (info.requestUrl)
Now I want to get post data, how can I get it?
help!!!!! thank you