我应该使用 req.body.item 从 post 请求中获取 body 吗？

我学会了在使用 express 时如何从 post 请求中获取正文数据。大多数示例代码表示req.body.item应该能够获取我想要使用的值，例如，将值插入表中。

但是我无法获得价值，req.body.item但最终可以通过req.body.body.value. 我是不是没有以正确的方式获取 post body 值，或者这不是问题？

Node.js
  v14.15.4
Nuxt.js
  @ v2.15.4
Vue.js
  [email protected]
Express
  ^4.17.1

(expense.vue)，使用正确的代码
发布表单数据更新为“books/books/add”

<template>
  <div>
    <div class="main">
      <h3>please type expense name and amount</h3>
      <form @submit.prevent="addToBookDB">
        <label for="name_expense">expense name: </label>
        <input v-model.trim="expenseTitle" />
        <label for="price_expense">expense amount: </label>
        <input v-model="expenseSummary" />
        <input type="submit" value="Submit" />
      </form>
    </div>
  </div>
</template>

<script>
import Vue from 'vue'
import axios from 'axios'

Vue.config.productionTip = false

export default {
  data () {
    return {
      expenseTitle: 'Title',
      expenseSummary: 'Summary',
    }
  },
  methods: {
    addToBookDB (event) {
      console.log(event)
      const formData = {
        expenseTitle: this.expenseTitle,
        expenseSummary: this.expenseSummary
      }
      console.log(JSON.stringify(formData))
      //<<wrong code↓>>
      //axios.post('books/books/add', {
      //  headers: {
      //    'Content-Type': 'application/json'
      //  },
      //  body: formData
      //<<correct code↓>>
      axios.post('books/books/add', formData
      ).then((response) => {
        console.log(response)
        return response
      }).catch((response) => {
        console.log(response)
        return response
      })
    }
  }
}
</script>

(books.js)，更新了正确的代码，
将收到的帖子数据插入到表中

const express = require('express')
const app = express()

app.use(express.json())
app.use(express.urlencoded({
  extended: true
}))

app.get('/books', (req, res) => {
  // (omitted)
})

app.post('/books/add', (req, res, next) => {
  const mysql = require('mysql')
  const connection = mysql.createConnection({
    host: '***.*.*.*',
    user: '******',
    database: '******',
    password: '******',
  })
  connection.connect()
  //const expenseTitle = req.body.body.expenseTitle
  const expenseTitle = req.body.expenseTitle
  connection.query("INSERT INTO book (title, summary) values (?,'1000');", [expenseTitle], function (error, row, fields) {
    res.redirect('./')
  })
  connection.end()
})

module.exports = {
  path: '/books',
  handler: app,
}