Myujth

I am reading a CSV using CSV-parser npm module and have to perform some operation on the data I get from the CSV (for each line).

const readstream = fs.createReadStream('src/working_file.csv');
const stream = readstream.pipe(parser());
 stream.on('data', async data => 
 // data is a JSON object of the row in CSV. 
 // Now i am calling another async function from user using the data in the JSON
 console.log('before calling');
 const writeToFile = await getImage(data.searchKey);
 console.log('after calling');
 // do other stuff


async function getImage(searchKey)
// im doing web scraping here using puppeeter
// it has some await calls too
console.log('in getimage');
 const results = await scrapper.run().catch(err => 
 console.error(err);
 process.exit(1);
 );

let say my csv has 2 rows then, my output is coming like below

before calling
in getimage
before calling
in getimage
after calling
after calling

but when I am doing this all callings are happening at a time though I used await. If I have 10 rows in the CSV all 10 rows calling the function is happening at the same time. but I want it to happen one by one. Only when the operation with the first row completes then I want the operate the second row.

my problem is all calls are happening at once rather than once by one.

Try this code.

var fs = require('fs');
var parse = require('csv-parse');
var async = require('async');

var inputFile='src/working_file.csv';

var parser = parse(delimiter: ',', function (err, data) 
 async.eachSeries(data, function (line, callback) 
 // do something with the line
 doSomething(line).then(function() 
 // when processing finishes invoke the callback to move to the next one
 callback();
 );
 )
);
fs.createReadStream(inputFile).pipe(parser);

You can also use fast-csv