CSV Parse Examples

Using the callback API

The parser receives a string and returns an array inside a user-provided callback. This example is available with the command node samples/callback.js.

var parse = require('csv-parse');
require('should');

var input = '#Welcome\n"1","2","3","4"\n"a","b","c","d"';
parse(input, {comment: '#'}, function(err, output){
  output.should.eql([ [ '1', '2', '3', '4' ], [ 'a', 'b', 'c', 'd' ] ]);
});

Using the stream API

The CSV parser implements the [stream.TransformAPI][stream_transform].

CSV data is sent through the write function and the resulting data is obtained within the "readable" event by calling the read function. This example is available with the command node samples/stream.js.

var parse = require('csv-parse');
require('should');

var output = [];
// Create the parser
var parser = parse({delimiter: ':'});
// Use the writable stream api
parser.on('readable', function(){
  while(record = parser.read()){
    output.push(record);
  }
});
// Catch any error
parser.on('error', function(err){
  console.log(err.message);
});
// When we are done, test that the parsed output matched what expected
parser.on('finish', function(){
  output.should.eql([
    [ 'root','x','0','0','root','/root','/bin/bash' ],
    [ 'someone','x','1022','1022','a funny cat','/home/someone','/bin/bash' ]
  ]);
});
// Now that setup is done, write data to the stream
parser.write("root:x:0:0:root:/root:/bin/bash\n");
parser.write("someone:x:1022:1022:a funny cat:/home/someone:/bin/bash\n");
// Close the readable stream
parser.end();

Using the pipe function

One useful function of the Stream API is pipe to interact between multiple streams. You may use this function to pipe a stream.Readable string source to a stream.Writable object destination. This example is available as node samples/pipe.js and reads the file, parses its content and transforms it.

var fs = require('fs');
var parse = require('csv-parse');
var transform = require('stream-transform');

var output = [];
var parser = parse({delimiter: ':'})
var input = fs.createReadStream('/etc/passwd');
var transformer = transform(function(record, callback){
  setTimeout(function(){
    callback(null, record.join(' ')+'\n');
  }, 500);
}, {parallel: 10});
input.pipe(parser).pipe(transformer).pipe(process.stdout);

Using the synchronous API

The parser receives a string and returns an array of objects. This example also illustrate the "columns" options which return records as object instead of arrays. This example is available with the command node samples/callback.js.

var parse = require('csv-parse/lib/sync');
require('should');

var input = '"key_1","key_2"\n"value 1","value 2"';
var records = parse(input, {columns: true});
records.should.eql([{ key_1: 'value 1', key_2: 'value 2' }]);