Why does my old folium app stopped show maps [duplicate] - pyqt5

Question

I wrote a python test program like this to show openstreetmap:
from PyQt5.QtWidgets import QApplication
from PyQt5.QtCore import QUrl
from PyQt5.QtWebEngineWidgets import QWebEngineView
import sys
def mainPyQt5():
url = 'file:///./index.html'
app = QApplication(sys.argv)
browser = QWebEngineView()
browser.load(QUrl(url))
browser.show()
sys.exit(app.exec_())
mainPyQt5()
index.html fetched by QWebEngineView simply calls openstreetmap:
<title>OSM and Leaflet</title>
<link rel = "stylesheet" href = "http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.css"/>
<div id = "map" style = "width: 900px; height: 580px"></div><script src = "http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.js"></script>
<script>
// Creating map options
var mapOptions = {
center: [45.641174, 9.114828],
zoom: 10
}
// Creating a map object
var map = new L.map('map', mapOptions);
// Creating a Layer object
var layer = new L.TileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png');
// Adding layer to the map
map.addLayer(layer);
</script>
If I fetch index.html with a ordinary browser the map is shown as expected but if I call the simple python program using QWebEngineView no tiles are downloaded from openstreetmap. If I replace openstreetmap with maps.stamen.com everything is fine both with a browser or the python script.

Answer 1

By default QtWebEngine does not set default headers like popular browsers do. In this case the openstreetmap server needs to know the "Accept-Language" to produce the maps since for example the names of the cities will depend on the language to filter non-browser traffic. The solution is to implement a QWebEngineUrlRequestInterceptor that adds that header:
import os.path
import sys
from PyQt5.QtCore import QUrl
from PyQt5.QtWidgets import QApplication
from PyQt5.QtWebEngineCore import QWebEngineUrlRequestInterceptor
from PyQt5.QtWebEngineWidgets import QWebEngineView
class Interceptor(QWebEngineUrlRequestInterceptor):
def interceptRequest(self, info):
info.setHttpHeader(b"Accept-Language", b"en-US,en;q=0.9,es;q=0.8,de;q=0.7")
def mainPyQt5():
CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))
filename = os.path.join(CURRENT_DIR, "index.html")
app = QApplication(sys.argv)
browser = QWebEngineView()
interceptor = Interceptor()
browser.page().profile().setUrlRequestInterceptor(interceptor)
browser.load(QUrl.fromLocalFile(filename))
browser.show()
sys.exit(app.exec_())
if __name__ == "__main__":
mainPyQt5()