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问题描述
我将Promise与Express结合使用.
I am using Promise with Express.
router.post('/Registration', function(req, res) {
var Promise = require('promise');
var errorsArr = [];
function username() {
console.log("1");
return new Promise(function(resolve, reject) {
User.findOne({ username: req.body.username }, function(err, user) {
if(err) {
reject(err)
} else {
console.log("2");
errorsArr.push({ msg: "Username already been taken." });
resolve(errorsArr);
}
});
});
}
var username = username();
console.log(errorsArr);
});
当我登录errorsArray时，它是空的，我不知道为什么.我是node.js的新手.预先感谢.
When I log errorsArray, it is empty and I don't know why. I am new in node.js. Thanks in advance.
推荐答案
尝试以下操作，然后请阅读以下文档 https://www.promisejs.org/了解承诺的工作方式.
Try the following, and after please read the following document https://www.promisejs.org/ to understand how the promises work.
var Promise = require('promise');
router.post('/Registration',function(req,res,next) {
function username() {
console.log("agyaaa");
return new Promise(function(resolve,reject) {
User.findOne({"username":req.body.username}, function(err,user) {
if (err) {
reject(err)
} else {
console.log("yaha b agyaaa");
var errorsArr = [];
errorsArr.push({"msg":"Username already been taken."});
resolve(errorsArr);
}
});
});
}
username().then(function(data) {
console.log(data);
next();
});
});
您也可能会遇到其他错误(或者不应该那样做的事情).我只是向您展示Promise的基本用法.
You can have other errors also (or things that shouldn't be done that way). I'm only showing you the basic use of a Promise.
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