猫鼬 findOne() 不返回承诺

Question

总结

我正在关注此course on Udemy，并以完成此app on github 结束。

我在第 10 课上遇到困难，我需要创建一个用户注册 API，然后通过发出 AJAX POST 请求进行测试，当我尝试发出 fetch POST 时收到此错误消息。

当我尝试使用 节点调试器 进行测试时，即node --inspect=0.0.0.0:9229 server.js

我看到代码没有在第 29 行停止执行下面的.then 承诺。

这似乎表明findOne() 没有返回应有的 Promise，尽管我可以从我在 Udemy 上做的课程中看到它是。此外，Mongoose documentation 表示它也返回了一个 Promise。

我已将所有代码上传到here on GitHub，以便更容易重现。但是所有相关的代码和日志也在下面。

---

环境

• OSX 10.13.3
• 节点 v8.11.1
• MongoDB shell 版本 v4.0.1
• MongoDB服务器版本v4.0.1

---

日志

这是服务器控制台的输出，我发出获取请求后没有有用的错误消息...

in ~/devconnector
$ (master) npm run debug

> devconnector@1.0.0 debug /Users/holly/devconnector
> node --inspect=0.0.0.0:9229 server.js

Debugger listening on ws://0.0.0.0:9229/22164c98-654b-4056-9bae-9a8b8cf96ddf
For help see https://nodejs.org/en/docs/inspector
(node:1892) 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.
Server running on port 5000
MongoDB Connected
Debugger attached.

这是 mongo DB 日志，我在前端发出 fetch 请求后没有任何输出...

$ mongod
2018-09-09T12:12:03.431+0100 I CONTROL  [main] Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten] MongoDB starting : pid=1932 port=27017 dbpath=/data/db 64-bit host=hollys-MacBook-Pro.local
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten] db version v4.0.1
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten] git version: 54f1582fc6eb01de4d4c42f26fc133e623f065fb
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten] allocator: system
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten] modules: none
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten] build environment:
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten]     distarch: x86_64
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten]     target_arch: x86_64
2018-09-09T12:12:03.445+0100 I CONTROL  [initandlisten] options: {}
2018-09-09T12:12:03.446+0100 I STORAGE  [initandlisten] Detected data files in /data/db created by the 'wiredTiger' storage engine, so setting the active storage engine to 'wiredTiger'.
2018-09-09T12:12:03.446+0100 I STORAGE  [initandlisten] wiredtiger_open config: create,cache_size=7680M,session_max=20000,eviction=(threads_min=4,threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,archive=true,path=journal,compressor=snappy),file_manager=(close_idle_time=100000),statistics_log=(wait=0),verbose=(recovery_progress),
2018-09-09T12:12:04.105+0100 I STORAGE  [initandlisten] WiredTiger message [1536491524:105407][1932:0x7fffa4bb1340], txn-recover: Main recovery loop: starting at 7/8320
2018-09-09T12:12:04.190+0100 I STORAGE  [initandlisten] WiredTiger message [1536491524:190433][1932:0x7fffa4bb1340], txn-recover: Recovering log 7 through 8
2018-09-09T12:12:04.247+0100 I STORAGE  [initandlisten] WiredTiger message [1536491524:247607][1932:0x7fffa4bb1340], txn-recover: Recovering log 8 through 8
2018-09-09T12:12:04.290+0100 I STORAGE  [initandlisten] WiredTiger message [1536491524:290380][1932:0x7fffa4bb1340], txn-recover: Set global recovery timestamp: 0
2018-09-09T12:12:04.424+0100 I RECOVERY [initandlisten] WiredTiger recoveryTimestamp. Ts: Timestamp(0, 0)
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten]
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten]
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] ** WARNING: This server is bound to localhost.
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] **          Remote systems will be unable to connect to this server.
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] **          Start the server with --bind_ip <address> to specify which IP
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] **          addresses it should serve responses from, or with --bind_ip_all to
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] **          bind to all interfaces. If this behavior is desired, start the
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten] **          server with --bind_ip 127.0.0.1 to disable this warning.
2018-09-09T12:12:04.593+0100 I CONTROL  [initandlisten]
2018-09-09T12:12:04.750+0100 I FTDC     [initandlisten] Initializing full-time diagnostic data capture with directory '/data/db/diagnostic.data'
2018-09-09T12:12:04.754+0100 I NETWORK  [initandlisten] waiting for connections on port 27017
2018-09-09T12:12:12.339+0100 I NETWORK  [listener] connection accepted from 127.0.0.1:56872 #1 (1 connection now open)
2018-09-09T12:12:12.346+0100 I NETWORK  [conn1] received client metadata from 127.0.0.1:56872 conn1: { driver: { name: "nodejs", version: "3.1.4" }, os: { type: "Darwin", name: "darwin", architecture: "x64", version: "17.4.0" }, platform: "Node.js v8.11.1, LE, mongodb-core: 3.1.3" }

---

这是我的代码...

routes/api/users.js

const express = require("express");
const router = express.Router();
const gravatar = require("gravatar");
const bcrypt = require("bcryptjs");

// Load User model
const User = require("../../models/User");

// @route   GET api/users/test
// @desc    Tests users route
// @access  Public
router.get("/test", (req, res) => res.json({ msg: "Users Works" }));

// @route   GET api/users/register
// @desc    Register user
// @access  Public
router.post("/register", (req, res) => {
  // function later(delay) {
  //   return new Promise(function(resolve) {
  //     setTimeout(resolve, delay);
  //   });
  // }
  // later(1000).then(() => {
  //   console.log("promise worked!");
  //   res.json({ msg: "promise worked!" });
  // });
  User.findOne({ email: req.body.email })
    .then(user => {
      if (user) {
        return res.status(400).json({ email: "Email already exists" });
      } else {
        const avatar = gravatar.url(req.body.email, {
          s: "200", // Size
          r: "pg", // Rating
          d: "mm" // Default
        });

        const newUser = new User({
          name: req.body.name,
          email: req.body.email,
          avatar,
          password: req.body.password
        });

        bcrypt.genSalt(10, (err, salt) => {
          bcrypt.hash(newUser.password, salt, (err, hash) => {
            if (err) throw err;
            newUser.password = hash;
            newUser
              .save()
              .then(user => res.json(user))
              .catch(err => console.log(err));
          });
        });
      }
    })
    .catch(err => {
      console.log(err);
    });
});

module.exports = router;

models/User.js

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

// Create Schema
const UserSchema = new Schema({
  name: {
    type: String,
    required: true
  },
  email: {
    type: String,
    required: true
  },
  password: {
    type: String,
    required: true
  },
  avatar: {
    type: String
  },
  date: {
    type: Date,
    default: Date.now
  }
});

module.exports = User = mongoose.model("users", UserSchema);

server.js

const express = require("express");
const mongoose = require("Mongoose");
const bodyParser = require("body-parser");

const users = require("./routes/api/users");
const profile = require("./routes/api/profile");
const posts = require("./routes/api/posts");

const app = express();

// Body parser middleware
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

// DB Config
const db = require("./config/keys").mongoURI;

// Connect to Mongo DB
mongoose
  .connect(db)
  .then(() => {
    console.log("MongoDB Connected");
  })
  .catch(err => console.log(err));

app.get("/", (req, res) => res.send("Hello World"));

// Use Routes
app.use("/api/users", users);
app.use("/api/profile", profile);
app.use("/api/posts", posts);

const port = process.env.PORT || 5000;

app.listen(port, () => console.log(`Server running on port ${port}`));

Answer 1

问题是您需要在 server.js（“Mongoose”）和 models/User.js（“mongoose”）中使用不同名称的 Mongoose 模块。这会创建模块的单独实例，因此由 server.js 建立的连接对 User 模型不可用，并且 findOne 调用在等待连接时被卡住。

所以只需将 server.js 中的那一行更改为：

const mongoose = require("mongoose");