我已经设计了一个评论系统，它可以在本地主机上完美运行。但是在将它部署到Heroku（我使用mLab代替本地mongoDB）后，它无法正常工作---提交后，新注释不会显示在页面上。
我很困惑，我只将本地mongoDB更改为mLab mongoDB。除此之外，我没有做任何其他更改。
下面是我的注释系统的node.js代码：
var EnglishofWords = [];
var CommentsArr = [];
mongoose.connect("mongodb://username:password@ds215172.mlab.com:15172/gredictionary")
app.post("/searchresult/comments", isLoggedIn, function(req, res){
var commentsText = req.body.text;
CommentsArr.push([commentsText, true]);
var EnglishofWord = EnglishofWords[EnglishofWords.length - 1];
var commentText = CommentsArr[CommentsArr.length - 1];
if (CommentsArr.length > 0) {
if (commentText[1] == true) {
grewords.findOne({English: EnglishofWord}, function(err, word){
if (err) {
console.log(err);
} else {
console.log("this step!")
comments.create({text: commentText[0], author: {id: req.user._id, username: req.user.username}, likes: 0, dislikes: 0}, function(err, comment){
if (err) {
console.log(err);
} else {
console.log("comment has been sumbited successfully!");
word.Comments.push(comment);
word.save();
}
});
}
});
CommentsArr[CommentsArr.length - 1][1] = false;
}
}
res.redirect("/searchresult");
})
///////////////////////////////////////////////// ///////////////////////////////////////////////////// ///////////////////////////////////////////////////// //////////
app.get("/searchresult", function(req, res){
var EnglishofWord = EnglishofWords[EnglishofWords.length - 1];
var WORDS = [];
grewords.findOne({English: EnglishofWord}).populate("Comments").exec(function(err, allgrewords){
if (err) {
console.log(err);
} else {
if (allgrewords == null || allgrewords.length < 1 || allgrewords == undefined ) {
res.render("errorpage");
} else {
if (req.isAuthenticated()) {
User.findOne({username: req.user.username}, function(err, user){
if (err) {
console.log(err);
} else {
grewords.findOne({English: EnglishofWord}, function(err, word){
if (err) {
console.log(err);
} else {
user.words.forEach(function(Word){
WORDS.push(Word.English);
});
if (WORDS.includes(word.English)) {
res.render("searchresult", {greword:allgrewords, signForUser: true});
} else {
res.render("searchresult", {greword:allgrewords, signForUser: false});
}
}
});
}
});
} else {
res.render("searchresult", {greword:allgrewords, signForUser: "notApplicable"});
}
}
}
});
});
有两个数据库：
var mongoose = require("mongoose");
var comments = require("./comments")
mongoose.connect("mongodb://username:password@ds215172.mlab.com:15172/gredictionary")
var words = [
{ English: "abstemious", Chinese: "（吃喝等）有节制的，节俭的", Synonym:
"continent", Antonym: "indulgent", Wordlist: false},
];
var wordsSchema = new mongoose.Schema({
English: String,
Chinese: String,
Synonym: String,
Antonym: String,
Wordlist: Boolean,
Comments: [
{
type:mongoose.Schema.Types.ObjectId,
ref:"comments"
}
]
});
wordsSchema.set('autoIndex', false);
var grewords = mongoose.model("grewords", wordsSchema);
for ( var i = 0; i < words.length; i++) {
grewords.create(words[i], function(err, word){
if (err) {
console.log(err);
} else {
console.log("DONE");
}
});
}
///////////////////////////////////////////////// ///////////////////////////////////////////////////// ///////////////////////////////////////////////////// //////////
var mongoose = require("mongoose");
mongoose.connect("mongodb://username:password@ds215172.mlab.com:15172/gredictionary")
var commentsSchema = new mongoose.Schema({
text: String,
likes: Number,
dislikes: Number,
author: {
id: {
type: mongoose.Schema.Types.ObjectId,
ref: "User"
},
username: String,
}
});
module.exports = mongoose.model("comments", commentsSchema);
太奇怪了，当我在Heroku上运行代码时，提交评论后，没有“这一步”和“评论已成功总结！”在控制台中，这意味着代码无法正常运行。但是实际上，我提交的新评论已成功添加到mLab数据库的集合中。我不知道这个问题，有人可以帮我解决这个问题吗？非常感谢！
以下是我的heroku日志的一部分：
2018-08-08T12:32:51.592865+00:00 app[web.1]: (node:20)
UnhandledPromiseRejectionWarning: Unhandled promise rejection. This
error originated either by throwing inside of an async function without
a catch block, or by rejecting a promise which was not handled with
.catch(). (rejection id: 1)
2018-08-08T12:32:51.592964+00:00 app[web.1]: (node:20) [DEP0018]
DeprecationWarning: Unhandled promise rejections are deprecated. In the
future, promise rejections that are not handled will terminate the
Node.js process with a non-zero exit code.
2018-08-08T12:32:51.812271+00:00 heroku[router]: at=info method=GET
path="/searchresult" host=agile-everglades-19141.herokuapp.com
request_id=d9275019-8f38-4a87-a171-d9fde7ae0a45 fwd="183.156.167.186"
dyno=web.1 connect=1ms service=15ms status=304 bytes=152 protocol=https
2018-08-08T12:32:52.103145+00:00 heroku[router]: at=info method=GET
path="/javascript/searchresult.js" host=agile-everglades-
19141.herokuapp.com request_id=69d58c11-0588-4b84-8a04-28bb2c8edf1e
fwd="183.156.167.186" dyno=web.1 connect=1ms service=48ms status=304
bytes=237 protocol=https
2018-08-08T12:32:52.074730+00:00 heroku[router]: at=info method=GET
path="/css/searchresult.css" host=agile-everglades-19141.herokuapp.com
request_id=d4fb1310-d87e-4260-8472-ae0d08663335 fwd="183.156.167.186"
dyno=web.1 connect=1ms service=21ms status=304 bytes=237 protocol=https
2018-08-08T12:32:52.318480+00:00 heroku[router]: at=info method=GET
path="/background_of_searchresult.jpg" host=agile-everglades-
19141.herokuapp.com request_id=96c60d28-765f-4c6d-aac9-78c0cf4a8fa8
fwd="183.156.167.186" dyno=web.1 connect=1ms service=8ms status=304
bytes=240 protocol=https
2018-08-08T13:08:52.907516+00:00 heroku[web.1]: Idling
2018-08-08T13:08:52.908137+00:00 heroku[web.1]: State changed from up to
down
2018-08-08T13:08:53.673180+00:00 heroku[web.1]: Stopping all processes
with SIGTERM
2018-08-08T13:08:53.753873+00:00 heroku[web.1]: Process exited with
status 143
2018-08-08T17:26:03.449270+00:00 heroku[web.1]: Unidling
2018-08-08T17:26:03.449527+00:00 heroku[web.1]: State changed from down
to starting
2018-08-08T17:26:06.709177+00:00 heroku[web.1]: Starting process with
command `npm start`
2018-08-08T17:26:08.485322+00:00 app[web.1]: > gredictionary@1.0.0 start
/app
2018-08-08T17:26:08.485299+00:00 app[web.1]:
2018-08-08T17:26:08.485324+00:00 app[web.1]: > node app.js
2018-08-08T17:26:08.485325+00:00 app[web.1]:
2018-08-08T17:26:09.807417+00:00 app[web.1]: Warning: connect.session()
MemoryStore is not
2018-08-08T17:26:09.807458+00:00 app[web.1]: designed for a production
environment, as it will leak
2018-08-08T17:26:09.807460+00:00 app[web.1]: memory, and will not scale
past a single process.
2018-08-08T17:26:09.819650+00:00 app[web.1]: (node:20)
DeprecationWarning: current URL string parser is deprecated, and will be
removed in a future version. To use the new parser, pass option {
useNewUrlParser: true } to MongoClient.connect.
2018-08-08T17:26:09.821394+00:00 app[web.1]: The web page has been
started!
2018-08-08T17:26:10.414286+00:00 heroku[web.1]: State changed from
starting to up
2018-08-08T17:26:11.540492+00:00 heroku[router]: at=info method=GET
path="/" host=agile-everglades-19141.herokuapp.com request_id=afc6fb6e-
aedd-4849-ae0b-33ab3eb7b2fa fwd="185.20.6.141" dyno=web.1 connect=0ms
service=25ms status=200 bytes=4321 protocol=https
2018-08-08T17:49:02.244137+00:00 heroku[router]: at=info method=GET
path="/" host=agile-everglades-19141.herokuapp.com request_id=27e6f629-
ccb4-419d-ab36-4a10beb37205 fwd="131.107.174.241" dyno=web.1 connect=0ms
service=4ms status=200 bytes=4323 protocol=https
2018-08-08T18:23:27.197045+00:00 heroku[web.1]: Idling
2018-08-08T18:23:27.197610+00:00 heroku[web.1]: State changed from up to
down
2018-08-08T18:23:28.084450+00:00 heroku[web.1]: Stopping all processes
with SIGTERM
2018-08-08T18:23:28.263192+00:00 heroku[web.1]: Process exited with
status 143
2018-08-09T06:01:41.214783+00:00 heroku[web.1]: Unidling
2018-08-09T06:01:41.215047+00:00 heroku[web.1]: State changed from down
to starting
2018-08-09T06:01:44.447331+00:00 heroku[web.1]: Starting process with
command `npm start`
2018-08-09T06:01:46.278298+00:00 app[web.1]:
2018-08-09T06:01:46.278311+00:00 app[web.1]: > gredictionary@1.0.0 start
/app
2018-08-09T06:01:46.278313+00:00 app[web.1]: > node app.js
2018-08-09T06:01:46.278314+00:00 app[web.1]:
2018-08-09T06:01:47.418611+00:00 app[web.1]: Warning: connect.session()
MemoryStore is not
2018-08-09T06:01:47.418674+00:00 app[web.1]: designed for a production
environment, as it will leak
2018-08-09T06:01:47.418676+00:00 app[web.1]: memory, and will not scale
past a single process.
2018-08-09T06:01:47.430402+00:00 app[web.1]: (node:20)
DeprecationWarning: current URL string parser is deprecated, and will be
removed in a future version. To use the new parser, pass option {
useNewUrlParser: true } to MongoClient.connect.
2018-08-09T06:01:47.432247+00:00 app[web.1]: The web page has been
started!
2018-08-09T06:01:47.697504+00:00 heroku[web.1]: State changed from
starting to up