JSPM – marc4js@0.0.1

Package Exports

marc4js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (marc4js) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

A Node.js module for handling MARC records

Installation

npm install marc4js

Examples

Examples can be found in the samples directory if source code is cloned from github.

Parsers

Parsers read different formats into marc4js.marc.Record objects.

Parse MARC file

`marc4js.parse`

marc4js.parse parse a string/Buffer in MARC format and creates marc4js.marc.Record objects.

Using the callback API

The parser receive a string/Buffer and return am array of marc4js.marc.Record objects inside a user-provided callback. This example is available with the command node samples/callback.js.

var marc4js = require('marc4js');
var fs = require('fs');
var should = require('should');

fs.readFile('samples/PGA-other-2.mrc', function(err, data) {
    marc4js.parse(data, {}, function(err, records) {
        records.length.should.eql(159);
    });
});

Using the stream API and pipe function

The following example uses the stream API of the parser. Since the parser always emit objects, it always uses the non-flowing mode - one can only attach a 'data' event listener, but not a 'readable' event listener. The object passed to the callback function in the 'data' event listener is a marc4js.marc.Record object.

var marc4js = require('marc4js');
var fs = require('fs');
var should = require('should');

var parser = marc4js.parse();
var records = [];
fs.readFile('samples/PGA-other-2.mrc', function(err, data) {
    parser.on('data', function (record) {
        records.push(record);
    });
    parser.on('error', function (error) {
        console.log("error: ", error);
    });
    parser.on('end', function () {
        records.length.should.eql(159);
    });
    parser.write(data.toString());
    parser.end();
});

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/parse_pipe.js. It reads a file, parses its content and then transform it back to MARC string.

var marc4js = require('marc4js');
var fs = require('fs');
var should = require('should');

var parser = marc4js.parse();
var stringifier = marc4js.stringify();

var records = [];
parser.on('data', function (record) {
    records.push(record);
});
parser.on('error', function (error) {
    console.log("error: ", error);
});
parser.on('end', function () {
    records.length.should.eql(159);
});

var is = fs.createReadStream('samples/PGA-other-2.mrc');
is.pipe(parser).pipe(stringifier).pipe(process.stdout);

This example uses the pipe and the stream API to parse a marc file.

var marc4js = require('marc4js');
var fs = require('fs');
var should = require('should');

var parser = marc4js.parse();

var records = [];
parser.on('data', function (record) {
    records.push(record);
});

parser.on('error', function (error) {
    console.log("error: ", error);
});

parser.on('end', function () {
    records.length.should.eql(159);
});

fs.createReadStream('samples/PGA-other-2.mrc').pipe(parser);

Transformers

Transformers transform the marc4js.marc.Record objects into other formats.

`marc4js.stringify`

marc4js.stringify converts marc4js.marc.Record objects into MARC strings.

Using the callback API

The following example uses the callback API. The API can convert a single record or an array of records into a string in MARC format. The following code snippet is part of the example code. For the full version, see samples/parse_pipe.js.

var marc4js = require('marc4js');

// build a record from scratch
var record = new marc4js.marc.Record();
// build the record ...

// converts a single record
marc4js.stringify(record, {}, function(err, data) {
    console.log(data);
});

// build an array of records
var records = [];
records.push(record);
var record2 = new marc4js.marc.Record();
// build the record ...
records.push(record2);

// converts an array of records
marc4js.stringify(records, {}, function(err, data) {
    console.log(data);
});

Using the stream API

Same as marc4js.parse, marc4js.stringify also provice usage through the stream API. Complete version of code is in samples/stringify_stream

var marc4js = require('marc4js');

var stringifier = marc4js.stringify();
var output = '';
stringifier.on('data', function(chunk) {
    output += chunk
});
stringifier.on('error', function(err) {
    console.log(err.message);
});
stringifier.on('end', function() {
    console.log(output);
});
var records = [];
// build records ...
records.forEach(function(record) {
    stringifier.write(record);
});
stringifier.end();

As shown in the parser examples, stringifier and other transformers can be used in a pipe that is in the down stream of a parser pipe. For details see the example samples/parser_pipe.js