nodejs require 找不到名称

Question

我正在尝试从导入中 return connection 的一个实例。

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

require("dotenv").config();

db = require('./services/db_service').db_connection() <---- here

var app = express();
app.use(bodyParser.json());

app.get('/customers' , (req, res) => {
    db.query('SELECT * FROM customers', (err, rows, fields) => {
        if (!err)
            res.send(rows);
        else
            console.log(err);
    })
} );

app.listen(process.env.PORT, function () {
  console.log(`Example app listening on port ${process.env.PORT}!`)
})

在 /services/db_service.ts 文件中：

export const db_connection = function () {
    const { HOST, USER, PASSWORD, DATABASE } = process.env
    var mysql = require('mysql');

    var con = mysql.createConnection({
      host: HOST,
      user: USER,
      password: PASSWORD,
      database: DATABASE,
      multipleStatements: true
    });

    con.connect(function(err) {
      if (err) throw err;
      console.log("Connected!");
    });

    return con; <--- return this

}

但是我得到这个错误：

index.ts:6:1 - error TS2304: Cannot find name 'db'.

db = require('./services/db_service').db_connection()

Answer 1

试试

const db = require('./services/db_service').db_connection()

此外，要优化与数据库的新连接，请参阅您正在使用的 ORM 文档

nodejs require 找不到名称

nodejs require cannot find name

mysql

require

node.js

express