[FIXED] Is there any way to call synchronously the method 'toHtml' which is QWebEnginePage's object?

Issue

I'm trying to get html code from the QWebEnginePage object. According to Qt reference, QWebEnginePage object's 'toHtml' is asynchronous method as below.

Asynchronous method to retrieve the page's content as HTML, enclosed in HTML and BODY tags. Upon successful completion, resultCallback is called with the page's content.

so I tried to find out how call this method synchronously.

the result what i want to get is below.

class MainWindow(QWidget):
  html = None
  ...
  ...
  def store_html(self, data):
    self.html = data

  def get_html(self):
    current_page = self.web_view.page()
    current_page.toHtml(self.store_html)
    # I want to wait until the 'store_html' method is finished
    # but the 'toHtml' is called asynchronously, return None when try to return self.html value like below.
    return self.html 
  ...
  ...

Solution

A simple way to get that behavior is to use QEventLoop(). An object of this class prevents the code that is after exec_() from being executed, this does not mean that the GUI does not continue working.

from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from PyQt5.QtWebEngineWidgets import *


class Widget(QWidget):
    toHtmlFinished = pyqtSignal()

    def __init__(self, *args, **kwargs):
        QWidget.__init__(self, *args, **kwargs)
        self.setLayout(QVBoxLayout())
        self.web_view = QWebEngineView(self)
        self.web_view.load(QUrl("http://doc.qt.io/qt-5/qeventloop.html"))
        btn = QPushButton("Get HTML", self)
        self.layout().addWidget(self.web_view)
        self.layout().addWidget(btn)
        btn.clicked.connect(self.get_html)
        self.html = ""

    def store_html(self, html):
        self.html = html
        self.toHtmlFinished.emit()

    def get_html(self):
        current_page = self.web_view.page()
        current_page.toHtml(self.store_html)
        loop = QEventLoop()
        self.toHtmlFinished.connect(loop.quit)
        loop.exec_()
        print(self.html)


if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

Note: The same method works for PySide2.

Answered By - eyllanesc