from PyQt5.QtXml import QDomDocument
from qgis.core import QgsReadWriteContext


def change_datasource(layer, target_uri):
    doc = QDomDocument("styles")
    element = doc.createElement("maplayer")
    layer.writeLayerXml(element, doc, QgsReadWriteContext())
    element.elementsByTagName("datasource").item(0).firstChild().setNodeValue(target_uri.uri())
    layer.readLayerXml(element, QgsReadWriteContext())
    # layer.setDataSource(new_datasource, new_name, 'ogr')