AWS Lambda(Node.js)转Office文件为PDF遇TypeError报错求助

开发一款基于Lambda Layer中LibreOffice的AWS Lambda(Node.js)函数，用于将Office文件转换为PDF。调试时多次出现不同报错，当前遇到的错误：

"errorType": "TypeError", "errorMessage": "Cannot read properties of undefined (reading '0')"

报错位置在/var/task/index/index.js第36行，对应代码：body = event.Records[0].body;。尝试直接指定文件名（test.doc）但无效，使用的代码如下：

const https = require('https');
const path = require('path');
const fs = require('fs');
var async = require('async');
const {writeFileSync} = require('fs');
const lambdafs = require('lambdafs');
const {execSync} = require('child_process');
var AWS = require('aws-sdk');

const inputPath = path.join( '/opt', 'lo.tar.br'); 
const outputPath = '/tmp/';
const bucketName = 'doc-conversion-tests';

module.exports.handler = async (event, context) => {
  console.log(execSync('ls -alh /opt').toString('utf8'));

  try {
    // Decompressing
    let decompressed = {
      file: await lambdafs.inflate(inputPath)
    };

    console.log('output brotli de:----', decompressed); 
  } catch (error) {
    console.log('Error brotli de:----', error);
  }

  try {
    console.log(execSync('ls -alh /opt').toString('utf8')); 
  } catch (e) {
    console.log(e);
  }

  var body = "";
  //S3 put event
  body = event.Records[0].body;
  console.log('s3 bucket file name from event:', body);

  // get file from s3 bucket
  var s3fileName = body;
  var newFileName = Date.now()+'.pdf';
  var s3 = new AWS.S3({apiVersion: '2006-03-01'});
  var fileStream = fs.createWriteStream('/tmp/'+s3fileName);

  var getObject = function(keyFile) {
      return new Promise(function(success, reject) {
          s3.getObject(
              { Bucket: bucketName, Key: keyFile },
              function (error, data) {
                  if(error) {
                      reject(error);
                  } else {
                      success(data);
                  }
              }
          );
      });
  }

  let fileData = await getObject(s3fileName);
    try{  
      fs.writeFileSync('/tmp/'+s3fileName, fileData.Body);
    } catch(err) {
      // An error occurred
      console.error('file write:', err);
    }

    const convertCommand = `export HOME=/tmp && /tmp/lo/instdir/program/soffice.bin --headless --norestore --invisible --nodefault --nofirststartwizard --nolockcheck --nologo --convert-to "pdf:writer_pdf_Export" --outdir /tmp /tmp/${s3fileName}`;
    try {
      console.log(execSync(convertCommand).toString('utf8'));
    } catch (e) {
      console.log(execSync(convertCommand).toString('utf8'));
    }
    console.log(execSync('ls -alh /tmp').toString('utf8'));

    function uploadFile(buffer, fileName) {
     return new Promise((resolve, reject) => {
      s3.putObject({
       Body: buffer,
       Key: fileName,
       Bucket: bucketName,
      }, (error) => {
       if (error) {
        reject(error);
       } else {

        resolve(fileName);
       }
      });
     });
    }


    let fileParts = s3fileName.substr(0, s3fileName.lastIndexOf(".")) + ".pdf";
    let fileB64data = fs.readFileSync('/tmp/'+fileParts);
    await uploadFile(fileB64data, 'pdf/'+fileParts);
    console.log('new pdf converted and uploaded!!!');
};

第36行报错是因为event.Records未定义，说明当前Lambda触发的事件不是S3 Put事件结构：

• 手动测试时用了默认测试事件，而非正确的S3事件模板；
• 通过其他方式触发Lambda，事件结构不符合S3上传格式；
• 直接指定文件名时，未注释掉依赖event.Records的代码，导致代码仍尝试读取不存在的字段。

1. 确保触发事件为正确的S3 Put结构 #

如果通过S3上传触发Lambda，确认S3触发器已正确配置；如果手动测试，使用AWS提供的S3 Put事件模板，示例结构如下：

{
  "Records": [
    {
      "body": "test.doc"
    }
  ]
}

2. 添加事件校验，避免崩溃 #

在读取event.Records前增加判断，防止因事件格式错误导致函数崩溃：

var body = "";
// 校验事件结构
if (event.Records && event.Records.length > 0) {
  body = event.Records[0].body;
  console.log('s3 bucket file name from event:', body);
} else {
  // 测试时手动指定文件名
  body = "test.doc";
  console.log('Using manual test filename:', body);
}
var s3fileName = body;

3. 手动测试时的正确方式 #

如果要跳过S3事件直接测试文件转换，直接给s3fileName赋值，并注释掉读取event.Records的代码：

// 注释掉原事件读取代码
// var body = "";
// body = event.Records[0].body;
// console.log('s3 bucket file name from event:', body);

// 手动指定文件名
var s3fileName = "test.doc";

4. 额外检查点 #

• 确认Lambda Layer中的lo.tar.br已正确部署，解压路径/tmp/lo存在；
• 检查S3桶doc-conversion-tests中存在test.doc文件，且Lambda有该桶的读写权限；
• 转换命令中的LibreOffice路径/tmp/lo/instdir/program/soffice.bin是否正确，可通过ls -alh /tmp/lo/instdir/program确认文件存在。

内容的提问来源于stack exchange，提问作者Nitrox