def _get_dav_getctag(self, cr): dirobj = self.context._dirobj uid = self.context.uid ctx = self.context.context.copy() ctx.update(self.dctx) where = [('collection_id','=',self.dir_id)] bc_obj = dirobj.pool.get('basic.calendar') res = get_last_modified(bc_obj, cr, uid, where, context=ctx) return _str2time(res)