Adding a Tiles/wms? (openStreetMap) layer with python in QGIS

Question

In my QGIS python plugin I want to add a background map (if the user haven't added one), hence I think I missing something in the url for the Tiles/wms service.. (the function returns invalid layer) Any suggestions?

    sources = [layer.source() for layer in QgsProject.instance().mapLayers().values()]
    print(sources)
    source_found = False
    for source in sources:
        if 'xyz&url' in source:
            source_found = True
            print('found')
    if not source_found:
        print('adding')
        urlWithParams = 'type=xyz&url=http://a.tile.openstreetmap.org/%7Bz%7D/%7Bx%7D/%7By%7D.png&zmax=19&zmin=0&crs=EPSG3857'
        rlayer = QgsVectorLayer(urlWithParams, 'OpenStreetMap', 'wms')
        if rlayer.isValid():
            QgsProject.instance().addMapLayer(rlayer)
        else:
            print('invalid layer')

Answer 1

Tiles/WMS sources give you raster data. So, you have to use QgsRasterLayer() instead of QgsVectorLayer().

Try in this way:

...
    rlayer = QgsRasterLayer(urlWithParams, 'OpenStreetMap', 'wms') # EDIT THIS LINE

    if rlayer.isValid():
        QgsProject.instance().addMapLayer(rlayer)
    else:
        print('invalid layer')