异步函数的未处理承诺拒绝

Question

我的快速后端收到未处理的承诺拒绝警告。我不完全确定如何解决这个问题，因为我以前从未与 Express 合作过。

//run function
function run(TrainLine, StartStation, EndStation,ArrivalTime,ArrivalDate) {
return new Promise((resolve, reject) => {
var process = spawn('python3',["./python/main.py",
TrainLine,
StartStation,
EndStation,
ArrivalTime,
ArrivalDate
] );
const out = []
process.stdout.on(
'data',
(data) => {
out.push(data.toString());
logOutput('stdout')(data);
}
);
const err = []
process.stderr.on(
'data',
(data) => {
err.push(data.toString());
logOutput('stderr')(data);
}
);
process.on('exit', (code, signal) => {
logOutput('exit')(`${code} (${signal})`)
if (code !== 0) {
reject(new Error(err.join('n')))
return
}
try {
resolve(JSON.parse(out[0]));
} catch(e) {
next(e);
}
});
});
}
app.post('/commuterequest',async function(request,response){
console.log(request.body);
const outputjson =await run(request.body.TrainLine,request.body.StartStation, request.body.EndStation, request.body.ArrivalTime, request.body.ArrivalDate);
console.log(outputjson);
response.json(outputjson);
});
app.get('/express_backend', (req, res) => {
res.send({ express: 'connected to backend!' });
});

这是我定义的运行函数代码。我正在尝试将尝试捕获添加到原始的等待函数中。鉴于代码的语法，我不太确定如何做到这一点。

完整的错误消息

未处理的承诺拒绝警告：未处理的承诺拒绝。此错误起源于在没有 catch 块的异步函数内部抛出，或者拒绝未使用 .catch(( 处理的承诺。(拒绝 ID：4( 类型错误： 无法读取未定义的属性"训练线" at C：\Users\mokas\Downloads\MTA_Crunch\server.js：62：49 at Layer.handle [as handle_request] (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\layer.js：95：5( at next (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\route.js：137：13( at Route.dispatch (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\route.js：112：3( at Layer.handle [as handle_request] (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\layer.js：95：5( at C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\index.js：281：22 at Function.process_params (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\index.js：335：12( at next (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\index.js：275：10( at expressInit (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\middleware\init.js：40：5( at Layer.handle [as handle_request] (C：\Users\mokas\Downloads\MTA_Crunchode_modules\express\lib\router\layer.js：95：5(

Answer 1

Express的路由处理程序有 3 个参数。第三个参数是可选参数，它的作用是处理异步处理程序的拒绝错误。因此，您需要将被拒绝的错误传递给它。

app.post('/commuterequest',async function(request,response, next){
console.log(request.body);
try {
const outputjson =await run(request.body.TrainLine,request.body.StartStation, request.body.EndStation, request.body.ArrivalTime, request.body.ArrivalDate);
console.log(outputjson);
response.json(outputjson);
} catch (e) {
next(e);
}

});