javascript 类型错误：promise.then(...).then(...).then(...).then(...).catch 不是 Node Js 中的函数
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TypeError: promise.then(...).then(...).then(...).then(...).catch is not a function in Node Js
提问by Vandervidi
Im getting this error and i dont know how to solve it. In a node js server, i'm using some .then() function on a promise and at the end i placed a .catch() function that for some reason is not recognized. I have seen in many places in tutorials that this is how an error is handled. I'm not using any external libraries.
我收到此错误，我不知道如何解决。在节点 js 服务器中，我在 promise 上使用了一些 .then() 函数，最后我放置了一个 .catch() 函数，该函数由于某种原因无法识别。我在教程中的很多地方都看到这是处理错误的方式。我没有使用任何外部库。
The error :
错误 ：
TypeError: promise.then(...).then(...).then(...).then(...).catch is not a function
This is my code:
这是我的代码：
exports.joinAlbum = function(req, res){
var promise = Album.findOne().where({'shortId': req.body.shortId}).exec(); // Returns a promise
promise.then(function(albumDoc){
console.log('Then #1');
.....
}
return albumDoc.save(); // Returns a promise
})
.then(function(albumDoc){
console.log('Then #2');
.....
return User.findById(req.body.userId).exec(); // Returns a promise
})
.then(function(userDoc){
console.log('Then #3');
........
return userDoc.save(); // Returns a promise
})
// Return a response
.then(function(savedUserDoc){
console.log('Then #4');
return res.status(200).json({success: true});
})
//Error handler
.catch(function(err){
console.log('Catch #1');
console.log(err);
res.status(200).json({success: false});
});
}
If .catch() is not the correct way to handle promise error, what do you suggest? Im trying to avoid using external libraries and prefer using native javascript
如果 .catch() 不是处理承诺错误的正确方法，你有什么建议？我试图避免使用外部库，而更喜欢使用本机 javascript
EDIT: solution
编辑：解决方案
I added a npm module called blue-bird that helped me solve this.
我添加了一个名为 blue-bird 的 npm 模块，它帮助我解决了这个问题。
回答by dcochran
It looks like you're using Mongoose, which returns its own Promise, not the ES6 promise which includes a catch function. A mongoose Promise has no catch function. You can overwrite the default Promise that Mongoose uses, fortunately:
看起来您正在使用 Mongoose，它返回自己的 Promise，而不是包含 catch 函数的 ES6 承诺。猫鼬 Promise 没有 catch 功能。幸运的是，您可以覆盖 Mongoose 使用的默认 Promise：
http://eddywashere.com/blog/switching-out-callbacks-with-promises-in-mongoose/
http://eddywashere.com/blog/switching-out-callbacks-with-promises-in-mongoose/
