用 nestjs 写微信的自动回复消息功能，一直报错？

为了收到微信服务器的 xml 信息，我写了个 xml 解析的中间件；

import { Injectable, NestMiddleware } from '@nestjs/common'
import { Request } from 'express'
import * as xml2js from 'xml2js'

const parseString = xml2js.parseString

const parseXml = (xml: string): any => {
  return new Promise((resolve, reject) => {
    parseString(xml, { explicitArray: false }, function (err, result) {
      if (!err) {
        resolve(result)
      } else {
        reject(err)
        throw err
      }
    })
  })
}

@Injectable()
export class XMLMiddleware implements NestMiddleware {
  use (req: Request, res: any, next: () => void) {
    const buffer = []
    req.on('data', (data) => {
      buffer.push(data)
    })
    req.on('end', async () => {
      console.log(req.query)
      const msgXml = Buffer.concat(buffer).toString('utf-8')
      const xmlData = await parseXml(msgXml)
      req.body = xmlData
      next()
    })
  }
}

定义的 controller 如下

  @Public()
  @Post('callback')
  async postMsg (@Body() body: {xml: any}, @Req() req: Request, @Res() res: Response) {
    const xml = body.xml
    if (xml.MsgType.toLowerCase() === 'text') {
      const fromUserName = xml.FromUserName
      const toUserName = xml.ToUserName
      const content = xml.Content
      const replyXml = await this.weixinService.sendTextMsg(fromUserName, toUserName, content)
      console.log(replyXml)
      res.type('application/xml')
      res.end(replyXml)
    }
  }

当给微信发送消息的时候，是可以拿到微信服务器的 xml 消息的

结果如下

// query 信息
{
  signature: '5bd7841d375e610c6c78f1219d910acf0e61549d',
  timestamp: '1668078826',
  nonce: '1894931224',
  openid: 'o2gkvuBvc_il-f0As0GjBzlqknJo'
}
// body 信息
{
  xml: {
    ToUserName: 'gh_4440d1e4f1af',
    FromUserName: 'o2gkvuBvc_il-f0As0GjBzlqknJo',
    CreateTime: '1668078825',
    MsgType: 'text',
    Content: '123123',
    MsgId: '23881145195544631'
  }
}

所有实现感觉都没啥问题；但是就是回复不了信息

返回信息如下

// 收到 xml 信息
{
  xml: {
    ToUserName: 'gh_4440d1e4f1af',
    FromUserName: 'o2gkvuBvc_il-f0As0GjBzlqknJo',
    CreateTime: '1668078825',
    MsgType: 'text',
    Content: '123123',
    MsgId: '23881145195544631'
  }
}
// 返回给微信服务器的信息；
<xml><ToUserName><![CDATA[o2gkvuBvc_il-f0As0GjBzlqknJo]]></ToUserName><FromUserName><![CDATA[gh_4440d1e4f1af]]></FromUserName><CreateTime>1668078827925</CreateTime><MsgType><![CDATA[text]]></MsgType><Content><![CDATA[123123]]></Content></xml>

不知道是什么原因导致的回复不了！