Angular 我需要帮助根据id进行选择

我正在为服务器设置sequelizer，但出现了一个错误

TypeError:Customer.findById不是函数

我在《邮递员》中尝试我的数据，我得到了所有的数据和帖子，但按ID获取不起作用

controller.js

    const db=require('../database/config-seq');
    const Customer=db.customers;

//POST A CUSTOMER

    exports.create=(req,res)=>{
    Customer.create(req.body).then(customer=>{res.json(customer)})
}

//GET ALL CUSTOMERS

    exports.findAll=(req,res)=>{
    Customer.findAll().then(customers=>{res.json(customers)})
}

//GET BY ID

    exports.findById = (req, res) => {  
    Customer.findById(JSON.stringify(req.params.id)).then(customer => {
      res.json(customer);
    }).catch(err => {
      console.log(err);
      res.status(500).json({msg: "error", details: err});
    });
    };

//UPDATE A CUSTOMER


    exports.update=(req,res)=>{
    const id=req.body.id;
    Customer.update(req.body,{where:{id:id}} ).then(()=>res.status(200).json( 
    { mgs: "Updated Successfully -> Customer Id = " + id } ))
    }

//DELETE A CUSTOMER BY ID

    exports.delete=(req,res)=>{
    const id=req.body.id;
    Customer.destroy({where : {id:id} }).then(() => {
    res.status(200).json( { msg: 'Deleted Successfully -> Customer Id = ' + 
    id } )
    })
    }

我的路由器文件

router.js

module.exports = function(app) {

var customers = require('../controllers/controller');

// Create a new Customer
app.post('/api/customers', customers.create);

// Retrieve all Customer
app.get('/api/customers', customers.findAll);

// Retrieve a single Customer by Id
app.get('/api/customers/:id', customers.findById);

// Update a Customer with Id
app.put('/api/customers/:id', customers.update);

// Delete a Customer with Id
app.delete('/api/customers/:id', customers.delete);
}

我的服务器文件

server.js

var express = require('express');
var app = express();
var bodyParser = require('body-parser');
const db=require('./app/database/config-seq');

app.use(bodyParser.json())


db.sequelize.sync({force:true}).then(() => {
console.log('Drop and Resync with { force: true }');
})

require('./app/routes/routes')(app);

// Create a Server

var server = app.listen(8081, function () {

var host = server.address().address
var port = server.address().port

console.log("App listening at http://%s:%s", host, port)



})

npm开始工作，但是

在那之后，我使用了邮递员，我可以得到帖子和所有的客户，但不能通过ID，更新或删除

我明白了

---

TypeError:Customer.findById在新版Sequelize中不是函数，您需要使用findByPk来获取一个元组Customer。我想不需要JSON.stringify

  Customer.findByPk(req.params.id).then(customer => {
    res.json(customer);
  }).catch(err => {
    console.log(err);
    res.status(500).json({ msg: "error", details: err });
  });