Node.js结合Mongoose实现Post请求报错问题求助

问题 #

跟着旧教程构建API时，POST请求失败。使用.post(addNewCoordinates);时出现报错：

Error: Route.post() requires a callback function but got a [object Undefined]

GET请求正常，已尝试添加async/await但问题未解决。MongoDB已通过Compass创建数据库及集合，相关代码如下：

index.js #

import express from 'express';
import routes from './src/routes/coordinatesRoutes';
import mongoose from 'mongoose';
import bodyParser from 'body-parser';

const app = express();
routes(app)
const PORT = 1234;
// Will print at localhost:{Port}
app.get('/', (req, res) =>
  res.send(`Node and express server running on port ${PORT}`)
)
// Will print in terminal
app.listen(PORT, () =>
console.log(`Your server is running on port ${PORT}`))

// Database Setup

// mongoose connection
mongoose.Promise = global.Promise;
mongoose.connect('mongodb://localhost:27017/coordinates', {
  useNewUrlParser: true,
  useUnifiedTopology: true
})
//bodyparser setup
app.use(bodyParser.urlencoded({ extended: true}));
app.use(bodyParser.json());

app.use(function(req, res, next) {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
  next();
});

coordinatesController.js #

import mongoose from 'mongoose';
import { InputDataSchema } from '../models/coordinatesModel'
const InputData = mongoose.model('InputData', InputDataSchema);
const addNewCoordinates = async  (req,res) => {
  let newCoordinates =  new InputData(req.body);
   await newCoordinates.save((err, coordinates) => {
    if (err) {
      res.send(err)
    }
    res.json(coordinates)
  })
}

export default addNewCoordinates;

coordinatesModel.js #

import mongoose from 'mongoose';
const Schema = mongoose.Schema;
export const InputDataSchema = new Schema({
  latitude: {
    type: Number,
    required: "Enter latitude"
  },
  longitude: {
    type: Number,
    required: "Enter longitude"
  },
  altitude: {
    type: Number,
    required: "Enter altitude"
  },
  ecef: {
    type: Array
  },
  created_date: {
    type: Date,
    default: Date.now
  }
})

coordinatesRoute.js #

import addNewCoordinates  from '../controllers/coordinatesController'
const routes = (app) => {
    //create route for donations
    app.route('/lla')
      //create get request
      .get((req, res) =>
      res.send('GET request successful!'))
      //create post request
      .post((req, res) =>
      res.set('POST request successful!'));
      // This crashes and gives me a Route.post() requires a callback function but got a [object Undefined] so I'm just trying to focus on getting a post without really any data.
     //.post(addNewCoordinates);

    // create a new route so you can get these donation entries by their ID's
    app.route('/lla/:timestamp')
      //create put request
      .put((req, res) =>
      res.send('PUT request successful!'))
      //create delete request
      .delete((req, res) =>
      res.send('DELETE request successful'))
  }
  export default routes;

解决方案 #

1. 修复路由链式调用的语法错误 #

报错的直接原因是路由链式调用被提前终止：在coordinatesRoute.js中，第一个.post()后面的分号会结束整个app.route('/lla')的链式调用，导致后续的.post(addNewCoordinates)失去上下文，无法正确关联到路由对象。

修改coordinatesRoute.js的路由部分，去掉多余的分号，替换为正确的链式调用：

app.route('/lla')
  // GET 请求
  .get((req, res) => res.send('GET request successful!'))
  // 使用控制器方法处理POST
  .post(addNewCoordinates);

2. 修正控制器中的异步逻辑问题 #

你在addNewCoordinates中混用了await和回调函数，mongoose的save()方法如果传入回调就不会返回Promise，await无效，同时错误处理会导致重复发送响应。

修改coordinatesController.js的控制器方法，改用纯async-await写法：

import mongoose from 'mongoose';
import { InputDataSchema } from '../models/coordinatesModel'
const InputData = mongoose.model('InputData', InputDataSchema);

const addNewCoordinates = async (req, res) => {
  try {
    const newCoordinates = new InputData(req.body);
    const savedCoordinates = await newCoordinates.save();
    res.json(savedCoordinates);
  } catch (err) {
    res.status(400).send(err);
  }
}

export default addNewCoordinates;

3. 调整中间件与路由的加载顺序 #

在index.js中，你先挂载了路由，再设置body-parser和CORS中间件，导致路由无法解析请求体（POST的参数无法被读取）。

修改index.js的代码顺序，先完成数据库连接、中间件配置，再挂载路由和启动服务：

import express from 'express';
import routes from './src/routes/coordinatesRoutes';
import mongoose from 'mongoose';
import bodyParser from 'body-parser';

const app = express();
const PORT = 1234;

// 数据库连接
mongoose.Promise = global.Promise;
mongoose.connect('mongodb://localhost:27017/coordinates', {
  useNewUrlParser: true,
  useUnifiedTopology: true
});

// 中间件配置
app.use(bodyParser.urlencoded({ extended: true}));
app.use(bodyParser.json());

// CORS 配置
app.use(function(req, res, next) {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
  next();
});

// 挂载路由
routes(app);

// 根路由
app.get('/', (req, res) =>
  res.send(`Node and express server running on port ${PORT}`)
);

// 启动服务
app.listen(PORT, () =>
  console.log(`Your server is running on port ${PORT}`)
);

4. 修正测试POST的响应写法 #

原代码中res.set('POST request successful!')是设置响应头，不是发送响应内容，应该使用res.send()或res.json()。

完成以上修改后，POST请求即可正常工作，同时能正确处理数据保存和错误反馈。

内容的提问来源于stack exchange，提问作者Ikura