使用Node.js读取上传到Amazon s3存储桶的文件的内容

Question

I'm trying to write a program that will read the contents of a .csv or .txt file when it is uploaded to an s3 bucket and store the output as a variable so the code and interact with it depending on what the file contains. I have tried using fs, but I could not find anything else that could do the task. Please let me know how to do it or where I can find the answer or what is wrong with my code. Thanks!

var sdk = require('aws-sdk');
var nodemailer = require('nodemailer');
var async = require('async');
var fs = require('fs');

exports.handler = function(event, context) {

    var transport = nodemailer.createTransport({
        service: 'Yahoo',
        auth: {
            user: 'pni.robot@yahoo.com',
            pass: 'automatic545Emails'
        }
    });

        var srcKey    =
    decodeURIComponent(event.Records[0].s3.object.key.replace(/\*/g, " "));
    var arr = srcKey.split('.');
    var obj = decodeURIComponent(event.Records[0].s3.object);

    console.log(arr);
    //console.log(event.Records[0]);

    var fileType = arr.pop();
    var fileName = arr.join('.');

    console.log("File detected with name: " + fileName);
    console.log("File detected with extension: " + fileType);

    //The following code does not work
    //It cannot read srcKey because srcKey is just a text value
    //I am just keeping it here until I find a better alternative
    if (fileType === 'csv') {
        console.log('.csv file detected.');
        fs.readFile(srcKey, function(err, data) {
            if (err) {
                return console.error(err);
            }
            var contents = data.toString;
            console.log("Email Robot read: " + data.tostring());
            console.log(contents);
        });
    }; 

    var mailOptions = {
        from: 'pni.robot@yahoo.com',
        to: 'teranai@reed.edu',
        subject: 'Email Program',
        text: 'A .' + fileType + ' file titled "' + fileName + '.' + fileType + '" has been uploaded to the S3 bucket "pnilambdabucket".'
    }

    transport.sendMail(mailOptions, function(error, info){
        if(error){
            return console.log(error);
        }
        console.log('Message Sent: ' + info.response);
        context.done();
    });


};

Answer 1

If I had enough rep, this would just be a "comment"...

Have you looked at these NPM packages as an alternative to fs ?

https://www.npmjs.com/package/awssum-amazon-s3

https://www.npmjs.com/package/s3