How to transform input csv to output csv via pipes

[maxfi]

I'm trying to add an extra column to a csv file and would like to do this via streams utilising a pipe. This is what I have so far:

var fs = require('fs');
var csv = require("fast-csv");

var input = fs.createReadStream("input.csv");
var output = fs.createWriteStream("output.csv", {encoding: 'utf-8'});

var count = 1;

var csvStream = csv({rtrim: true, headers: true})
    .on("record", function(data){
        data.ordinalValue = count;
        count = count + 1;
     })
     .on("end", function(){
        console.log("done");
     });

input.pipe(csvStream).pipe(output);

It just puts a stringified JSON object though..

[doug-martin]

So, we had to do something similar, and with the latest version of fast-csv this is possible.

var fs = require('fs');
var csv = require("fast-csv");
var count = 1;
var csvOutputStream = csv.createWriteStream({rtrim: true, headers: true});
var output = csvOutputStream
    .pipe(fs.createWriteStream("output.csv", {encoding: 'utf-8'}))
    .on("finish", function () {
        console.log("done");
    });

csv.fromPath("input.csv", {rtrim: true, headers: true})
    .on("record", function (data) {
        data.ordinalValue = count;
        count = count + 1;
        csvOutputStream.write(data);
    })
    .on("end", function () {
        csvOutputStream.write(null);
    });