nodejs+express+mongoose操作mongodb增删改查

1. 安装依赖

安装`express`、`mongoose`、`body-parser`和`cors`：

npm install express mongoose body-parser cors --save

2. 连接数据库

在`app.js`中连接数据库：

const express = require('express');
const mongoose = require('mongoose');
const bodyParser = require('body-parser');
const cors = require('cors');

const app = express();

// 连接数据库
mongoose.connect('mongodb://localhost/test', { useNewUrlParser: true });
const db = mongoose.connection;
db.on('error', console.error.bind(console, '连接错误:'));
db.once('open', function() {
  console.log('连接成功');
});

app.use(bodyParser.json());
app.use(cors());

app.listen(3000, () => console.log('服务器已启动'));

3. 定义模型

在`models`文件夹下创建`user.js`文件，定义用户模型：

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
  name: String,
  age: Number,
  gender: String,
});

const User = mongoose.model('User', userSchema);

module.exports = User;

4. 增加数据

在`app.js`中增加路由，实现增加用户功能：

const express = require('express');
const mongoose = require('mongoose');
const bodyParser = require('body-parser');
const cors = require('cors');
const User = require('./models/user');

const app = express();

// 连接数据库
mongoose.connect('mongodb://localhost/test', { useNewUrlParser: true });
const db = mongoose.connection;
db.on('error', console.error.bind(console, '连接错误:'));
db.once('open', function() {
  console.log('连接成功');
});

app.use(bodyParser.json());
app.use(cors());

// 增加用户
app.post('/users', (req, res) => {
  const user = new User({
    name: req.body.name,
    age: req.body.age,
    gender: req.body.gender,
  });

  user.save((err, user) => {
    if (err) {
      console.error(err);
      res.sendStatus(500);
    } else {
      res.json(user);
    }
  });
});

app.listen(3000, () => console.log('服务器已启动'));

5. 查询数据

在`app.js`中增加路由，实现查询用户功能：

const express = require('express');
const mongoose = require('mongoose');
const bodyParser = require('body-parser');
const cors = require('cors');
const User = require('./models/user');

const app = express();

// 连接数据库
mongoose.connect('mongodb://localhost/test', { useNewUrlParser: true });
const db = mongoose.connection;
db.on('error', console.error.bind(console, '连接错误:'));
db.once('open', function() {
  console.log('连接成功');
});

app.use(bodyParser.json());
app.use(cors());

// 增加用户
app.post('/users', (req, res) => {
  const user = new User({
    name: req.body.name,
    age: req.body.age,
    gender: req.body.gender,
  });

  user.save((err, user) => {
    if (err) {
      console.error(err);
      res.sendStatus(500);
    } else {
      res.json(user);
    }
  });
});

// 查询用户
app.get('/users', (req, res) => {
  User.find((err, users) => {
    if (err) {
      console.error(err);
      res.sendStatus(500);
    } else {
      res.json(users);
    }
  });
});

app.listen(3000, () => console.log('服务器已启动'));

6. 更新数据

在`app.js`中增加路由，实现更新用户功能：

const express = require('express');
const mongoose = require('mongoose');
const bodyParser = require('body-parser');
const cors = require('cors');
const User = require('./models/user');

const app = express();

// 连接数据库
mongoose.connect('mongodb://localhost/test', { useNewUrlParser: true });
const db = mongoose.connection;
db.on('error', console.error.bind(console, '连接错误:'));
db.once('open', function() {
  console.log('连接成功');
});

app.use(bodyParser.json());
app.use(cors());

// 增加用户
app.post('/users', (req, res) => {
  const user = new User({
    name: req.body.name,
    age: req.body.age,
    gender: req.body.gender,
  });

  user.save((err, user) => {
    if (err) {
      console.error(err);
      res.sendStatus(500);
    } else {
      res.json(user);
    }
  });
});

// 查询用户
app.get('/users', (req, res) => {
  User.find((err, users) => {
    if (err) {
      console.error(err);
      res.sendStatus(500);
    } else {
      res.json(users);
    }
  });
});

// 更新用户
app.put('/users/:id', (req, res) => {
  User.findByIdAndUpdate(req.params.id, {
    $set: {
      name: req.body.name,
      age: req.body.age,
      gender: req.body.gender,
    },
  }, { new: true }, (err, user) => {
    if (err) {
      console.error(err);
      res.sendStatus(500);
    } else {
      res.json(user);