从主路由文件中调用Node.js模块函数

Question

在我的主路由文件中，我需要多次调用一段代码，所以我试图将这段代码放在一个名为"getDayWorkout"的单独模块中，这样我就不必一遍又一遍地重复了。我正在努力实现这一目标。现在，getDayWorkout函数被触发，但它没有到达其中的嵌套函数。下面是我的主路由文件中的代码，后面是导出为"getDayWorkut"的外部模块上的代码。感谢您的帮助。

const express = require('express')
const router = express.Router()
const connection = require('../../helpers/connection')
const getDayWorkout = require('../middlewares/getDayWorkout') // <= external module

router.get("/fetchcustomworkoutplan/:id", (req, res) => {
console.log('MENFIS39: ', req.params)
const userId = parseInt(req.params.id);
let queryString = "SELECT day_one, day_two, day_three, day_four, day_five, day_six, day_seven FROM user_workout_plans WHERE user_id = ? AND status = ?"
connection.query(queryString, [userId, 'Active'], async (err, rows, fields) => {
if (err) {
// // console.log(err)
res.status(500).json({error: 'error'})
return
}
if (rows.length === 0) {
res.json(rows)
return
}
console.log('wokour opans: ', rows)
const userWorkoutPlans = rows[0]
const { day_one, day_two, day_three, day_four, day_five, day_six, day_seven } = userWorkoutPlans
if (day_one !== null) {

workoutDayOne = await getDayWorkout(day_one)

}
res.json(res.workoutPlans)
})
})

getDayWorkout文件：

const connection = require('../../helpers/connection')
function getDayWorkout(dayWorkoutId) {
console.log('here', dayWorkoutId) // <= triggered
return (req, res, next) => {
console.log('here2') // <=  triggered
let queryString = "SELECT * FROM workout_sequences WHERE workout_id = ?"
connection.query(queryString, [dayWorkoutId], (err, rows, fields) => {
if (err) {
// // console.log(err)
res.status(500).json({error: 'error'})
return
}
console.log('hit')
return rows
})
}
}
module.exports = getDayWorkout;

Answer 1

如果要从getDayWorkout方法返回值，则需要callback或promise。由于JS是异步的，所以不能只返回异步调用的值。

以下是Promise的实现，您可以在其中使用await或then

const connection = require('../../helpers/connection')
function getDayWorkout(dayWorkoutId) {
return new Promise((resolve, reject) => {
console.log('here', dayWorkoutId) // <= triggered
console.log('here2') // <=  triggered
let queryString = "SELECT * FROM workout_sequences WHERE workout_id = ?"
connection.query(queryString, [dayWorkoutId], (err, rows, fields) => {
if (err) {
reject(err);         
return;
}
resolve(rows);
});
});
}
module.exports = getDayWorkout;