当我尝试执行节点js应用程序时出现错误：findById不是函数

Question

There is a error:

findById is not a function

when I'm trying to execute a node js app.
This is my code, exclusively for the eCommerce website.

const path = require('path');

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

const errorController = require('./controllers/error');
const sequelize = require('./util/database');
const Product = require('./models/product');
const User = require('./models/user');

const app = express();

app.set('view engine', 'ejs');
app.set('views', 'views');

const adminRoutes = require('./routes/admin');
const shopRoutes = require('./routes/shop');

app.use(bodyParser.urlencoded({ extended: false }));
app.use(express.static(path.join(__dirname, 'public')));

//findById methode

app.use((req, res, next) => {
  User.findById(1)
      .then(user => {
        req.user = user;
        next();
      })
      .catch(err => console.log(err));
});

//routes controller

app.use('/admin', adminRoutes);
app.use(shopRoutes);

app.use(errorController.get404);

Product.belongsTo(User, { constraints: true, onDelete: 'CASCADE' });
User.hasMany(Product);

//sequelize statements

sequelize
  // .sync({ force: true })
  .sync()
  .then(result => {
    return User.findById(1);
    // console.log(result);
  })
  .then(user => {
    if (!user) {
      return User.create({ name: 'Max', email: 'test@test.com' });
    }
    return User;
  })
  .then(user => {
    // console.log(user);

//port configuration

  app.listen(3000,() => console.log(`looking at local host port number 3000`));
})
.catch(err => {
  console.log(err);
});

Answer 1

This error means that findById is not defined in your user model. You'll need to add and export this method in your './models/user' module.

Answer 2

I think you want the Model method findByPk to "Search for a single instance by its primary key.") Try:

app.use((req, res, next) => {
  User.findByPk(1)
    .then(user => {