如果调用的函数没有在同一个文件中定义，为什么我的中间件功能不能工作？

Question

我所面对的问题如下：

案例1(工作案例) :

文件middleware.ts (中间件函数库)

import { NextApiRequest, NextApiResponse } from 'next'
import rateLimit from 'express-rate-limit'

export function runMiddleware(req: NextApiRequest, res: NextApiResponse, fn: Function) {
    return new Promise((resolve, reject) => {
      fn(req, res, (result: any) => {
        if (result instanceof Error) {
          return reject(result)
        }
        return resolve(result)
      })
    })
}

export const limiter = rateLimit({
    keyGenerator: function (req: any) {
        return req.headers["x-forwarded-for"] || req.connection.remoteAddress; 
    }, // Needed because of issue : https://issueexplorer.com/issue/nfriedly/express-rate-limit/254
    windowMs: 60 * 1000, // 1 minute
    max: 5, // 5 requests per IP
})

文件login.ts (我的API入口点)

import { NextApiRequest, NextApiResponse } from 'next'
import { limiter, runMiddleware } from '../../lib/middleware'

module.exports = async (req: NextApiRequest, res: NextApiResponse) => {


    // Run middlewares
    try {
        await runMiddleware(req, res, limiter)
    } catch {
        res.status(500)
        res.end(JSON.stringify({errorCode: 'unknown', errorValue: ''}))
        return
    }

    if (req.method === 'POST') {
        res.status(200)
        res.end(JSON.stringify({errorCode: 'ok', errorValue: ''}))
    }
}

在这种情况下，如果我尝试超过5次达到我的API，我会得到消息“太多的请求.”这就是我想要的。

案例2(非工作案例) :

文件middleware.ts (中间件函数库)

import { NextApiRequest, NextApiResponse } from 'next'

export function runMiddleware(req: NextApiRequest, res: NextApiResponse, fn: Function) {
    return new Promise((resolve, reject) => {
      fn(req, res, (result: any) => {
        if (result instanceof Error) {
          return reject(result)
        }
        return resolve(result)
      })
    })
}

文件login.ts (我的API入口点)

import { NextApiRequest, NextApiResponse } from 'next'
import rateLimit from 'express-rate-limit'
import { runMiddleware } from '../../lib/middleware'

// Run middlewares
    try {
        const limiter = rateLimit({
            keyGenerator: function (req: any) {
                return req.headers["x-forwarded-for"] || req.connection.remoteAddress; 
            }, // Needed because of issue : https://issueexplorer.com/issue/nfriedly/express-rate-limit/254
            windowMs: 60 * 1000, // 1 minute
            max: 5, // 5 requests per IP
        })
        await runMiddleware(req, res, limiter)
    } catch {
        res.status(500)
        res.end(JSON.stringify({errorCode: 'unknown', errorValue: ''}))
        return
    }

    if (req.method === 'POST') {
        res.status(200)
        res.end(JSON.stringify({errorCode: 'ok', errorValue: ''}))
    }

我看不出这两种情况之间的区别，这可以解释为什么在我的第二种情况下不起作用。有人有解释吗？

提前谢谢。

Answer 1

@juliomalves在评论中给出了答案：

“这是因为您在每个请求中声明并分配限幅器值，每次都会调用rateLimit。尝试将限制器声明移到处理程序函数之外。”