【发布时间】：2018-05-20 18:45:48
【问题描述】：
我的以下代码在 mongodb findAndUpdateOne 更新查询中有语法错误。
router.post('/buylicense', isLoggedIn, function(req, res) {
if (!req.body.cid) {
return res.send('failed');
}
Company.findOne({
ownedBy: req.user.local.username,
_id: req.body.cid
}, function(err, result) {
if (err) {
return res.send('failed');
}
if (result.license) {
return res.send('valid');
} else {
Company.findOneAndUpdate({
ownedBy: req.user.local.username,
_id: req.body.cid
}, {
license: true,
licenseExpireDate: {
$add: ["$date", 3 * 24 * 60 * 60000] // bad code, a problem for another day
}
}, function(err) {
if (err) {
console.log(err);
return res.end('failed'); // Code should stop here.
}
console.log('got here');
return res.send('success');
});
}
});
console.log('How did I get here?');
res.send('failed');
});
我的问题是为什么代码到达了代码的最后部分：
console.log('How did I get here?');
res.send('failed');
如果我使用 return res.end 以外的任何内容，代码将到达末尾并导致我的应用程序崩溃。简单地做res.end 不起作用，return res.send 也不起作用。 return 或至少 res.end 不应该足以真正阻止代码到达末尾吗？
如果我不停止right way 的错误，则会显示错误，可能不相关但在这里：
How did I get here?
{ CastError: Cast to date failed for value "[object Object]" at path "licenseExpireDate"
at MongooseError.CastError (/media/node_modules/mongoose/lib/error/cast.js:19:11)
at SchemaDate.cast (/media/node_modules/mongoose/lib/schema/date.js:242:9)
at SchemaDate.castForQuery (/media/node_modules/mongoose/lib/schema/date.js:276:17)
at Query._castUpdateVal (/media/node_modules/mongoose/lib/query.js:2477:17)
at Query._walkUpdatePath (/media/node_modules/mongoose/lib/query.js:2372:25)
at Query._castUpdate (/media/node_modules/mongoose/lib/query.js:2296:23)
at castDoc (/media/node_modules/mongoose/lib/query.js:2500:18)
at Query._findAndModify (/media/node_modules/mongoose/lib/query.js:1755:17)
at Query._findOneAndUpdate (/media/node_modules/mongoose/lib/query.js:1622:8)
at /media/node_modules/kareem/index.js:156:8
at args (/media/node_modules/kareem/index.js:71:20)
at Query.<anonymous> (/media/node_modules/mongoose/lib/schema.js:728:7)
at next (/media/node_modules/kareem/index.js:82:14)
at Kareem.execPre (/media/node_modules/kareem/index.js:99:3)
at Kareem.wrap (/media/node_modules/kareem/index.js:146:8)
at Query._findOneAndUpdate (/media/node_modules/kareem/index.js:188:11)
message: 'Cast to date failed for value "[object Object]" at path "licenseExpireDate"',
name: 'CastError',
kind: 'date',
value: { '$add': [ '$date', 259200000 ] },
path: 'licenseExpireDate',
reason: undefined }
got here
_http_outgoing.js:346
throw new Error('Can\'t set headers after they are sent.');
^
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:346:11)
at ServerResponse.header (/media/node_modules/express/lib/response.js:718:10)
at ServerResponse.send (/media/node_modules/express/lib/response.js:163:12)
at /media/sf_vShared/xyz/app/modalRoutes.js:461:28
at /media/node_modules/kareem/index.js:160:11
at Query._findAndModify (/media/node_modules/mongoose/lib/query.js:1767:14)
at Query._findOneAndUpdate (/media/node_modules/mongoose/lib/query.js:1622:8)
at /media/node_modules/kareem/index.js:156:8
at args (/media/node_modules/kareem/index.js:71:20)
at Query.<anonymous> (/media/node_modules/mongoose/lib/schema.js:728:7)
at next (/media/node_modules/kareem/index.js:82:14)
at Kareem.execPre (/media/node_modules/kareem/index.js:99:3)
at Kareem.wrap (/media/node_modules/kareem/index.js:146:8)
at Query._findOneAndUpdate (/media/node_modules/kareem/index.js:188:11)
at Query.findOneAndUpdate (/media/node_modules/mongoose/lib/query.js:1611:15)
at Function.Model.findOneAndUpdate (/media/node_modules/mongoose/lib/model.js:1491:13)
[nodemon] app crashed - waiting for file changes before starting...
【问题讨论】：
-
Mongoose 的 find 函数是异步的，这意味着它们独立于主线程和后台运行。调用
Company.findOne之后的代码会立即运行，您不应该在那里 res.end/send。而是像你已经做的那样在回调上这样做。 -
因此，对于任何猫鼬操作，阻止整个代码继续运行的方法是使用
return res.end还是有更好的方法？ -
return 结束任何函数，这对于 express 或 mongoose 来说并不是什么特别的东西。
res.send和end是为客户端返回数据的快速函数。