ya-csv

Event based CSV parser and writer for Node.js suitable for processing large CSV streams.

* Designed for high performance and ease of use.
* RFC 4180 compliance with optional extensions.
* Zero dependencies.

Example

``js
// A simple echo program:
var csv = require('ya-csv');

var reader = csv.createCsvStreamReader(process.openStdin());
var writer = csv.createCsvStreamWriter(process.stdout);

reader.addListener('data', function(data) {
writer.writeRecord(data);
});

reader.addListener('error', function(e) {
console.error('Oops!');
});
`

Installation


`bash
npm install ya-csv
`

Current version requires at least Node.js v0.2.3 and it's tested with Node.js v0.4.12, 0.6.11, 0.7.5 and v0.10.24. Hope it works with the other versions in between too.

Features

- event based, suitable for processing big CSV streams
- configurable separator, quote and escape characters (comma, double-quote and double-quote by default)
- ignores lines starting with configurable comment character (off by default)
- supports memory-only streaming

More examples

Echo first column of the data.csv file:
`js
// equivalent of csv.createCsvFileReader('data.csv')
var reader = csv.createCsvFileReader('data.csv', {
'separator': ',',
'quote': '"',
'escape': '"',
'comment': '',
});
var writer = new csv.CsvWriter(process.stdout);
reader.addListener('data', function(data) {
writer.writeRecord([ data[0] ]);
});
`

Return data in objects rather than arrays: either by grabbing the column names from the header row (first row is not passed to the data listener):
`js
var reader = csv.createCsvFileReader('data.csv', { columnsFromHeader: true });
reader.addListener('data', function(data) {
// supposing there are so named columns in the source file
sys.puts(data.col1 + " ... " + data.col2);
});
`

... or by providing column names from the client code (first row is passed to the data listener in this case):
`js
var reader = csv.createCsvFileReader('data.csv');
reader.setColumnNames([ 'col1', 'col2' ]);
reader.addListener('data', function(data) {
sys.puts(data.col1 + " ... " + data.col2);
});
`

Note reader.setColumnNames() resets the column names so next invocation of the data listener will again receive the data in an array rather than an object.

Convert the /etc/passwd file to comma separated format, drop commented lines and dump the results to the standard output:
`js
var reader = csv.createCsvFileReader('/etc/passwd', {
'separator': ':',
'quote': '"',
'escape': '"',
'comment': '#',
});
var writer = new csv.CsvWriter(process.stdout);
reader.addListener('data', function(data) {
writer.writeRecord(data);
});
`

Parsing an upload as the data comes in, using node-formidable:
`js
upload_form.onPart = function(part) {
if (!part.filename) { upload_form.handlePart(part); return }

var reader = csv.createCsvFileReader({'comment': '#'});
reader.addListener('data', function(data) {
saveRecord(data);
});

part.on('data', function(buffer) {
// Pipe incoming data into the reader.
reader.parse(buffer);
});
part.on('end', function() {
reader.end()
})
}
`

CsvReader Options

Note: the defaults are based on the values from RFC 4180 -
https://tools.ietf.org/html/rfc4180

* separator - field separator (delimiter), default: ',' (comma)
* quote - the character used to enclose fields with white space
characters, escaping etc., default: '"' (double quote)
* escape - character used to escape the quote inside a
field, default: '"' (double quote). If you are changing quotechar
you may want to change the escape to the same value
* comment - parser will ignore this character and all following
characters on the same line
the line, default: none
* columnNames - an array of column names, if used, the rows sent to
the data listener are represented as hashes instead of arrays,
default: none
* columnsFromHeader - boolean value indicating whether the first row
should be interpreted as a list of header names. If used, the rows
sent to the data listener are represented as hashes instead of arrays,
default: false
* nestedQuotes - boolean value indicating whether the parser should
try to process a file with unescaped quote characters inside fields,
default: false
* flags - a string with flags to be passed through to
createRead/WriteStream (only supported via createCsvFileReader
and createCsvFileWriter methods), default: none

CSvWriter Options

* separator - field separator (delimiter), default: ',' (comma)
* quote - the character used to enclose fields with white space
characters, escaping etc., default: '"' (double quote)
* escape - character used to escape the quote inside a
field, default: '"' (double quote). If you are changing quotechar
you may want to change the escape to the same value
* escapeFormulas - boolean value indicating whether the parser should
escape '=', '+' and '-' with an apostrophe to prevent some programs
from treating the content as an executable formula, default: false`