marc-transformed

Read, manipulate and write MARC records using NodeJS streams.

Compatibility

NodeJS v10 or later
TypeScript 2.8 or later

Examples

Converting a MARC file into text format

This example creates a text (MarcEdit-compatible) file from the records in a MARC file in transmission (aka binary) format. No changes are made to the fields and subfields in the records.

import fs from 'fs'
import { transformFrom, transformTo } from '@sydneyunilibrary/marc-transformed'

const inputFilename = 'input.mrc'
const outputFilename = 'output.mrk8'

console.log('Converting', inputFilename, 'to', outputFilename)
fs.pipeline(
  fs.createReadStream(inputFilename),
  transformFrom('marc'),
  transformTo('text'),
  fs.createWriteStream(outputFilename),
  err => {
    if (err) {
      console.error(err)
    } else {
      console.log('Done')
    }
  }
)

Template for altering records

This is some boiler-plate that you can use if you want to read in a file of records, work on each record in some way, and then write them out to a different file.

Note that this technique only works if you are working on one record at a time.

import fs from 'fs'
import { transformFrom, transformTo, transformRecord, Record } from '@sydneyunilibrary/marc-transformed'

const inputFilename = 'input.mrc'
const inputFormat = 'marc' // or 'json' or 'xml' or 'text'
const outputFilename = 'output.mrc'
const outputFormat = 'marc' // or 'json' or 'xml' or 'text'

function transformFunction(record: Record): Record | null | undefined {
  api.md
  // TODO: Return the record if you want to include it in the output file, 
  //       return null or undefined if you want to filter it out,
  //       or throw an Error if you want abort the program. 
  return record 
}

console.log('Transforming records in', inputFilename, 'into', outputFilename)
fs.pipeline(
  fs.createReadStream(inputFilename),
  transformFrom(inputFormat),
  transformRecord(transformFunction),
  transformTo(outputFormat),
  fs.createWriteStream(outputFilename),
  err => {
    if (err) {
      console.error(err)
    } else {
      console.log('Done')
    }
  }
)

Further documentation

marc-transformed has 2 major parts to its API.

Transform API - An API transforming to and from streams of bytes and streams of Record objects.
Record API - An API for creating, query and editing MARC records and fields.

Additionally:

If you not using marc-transformed but are hacking at the code for marc-transformed itself:

Internal API

Copyright

License

2-Clause BSD See the LICENSE file for details.

Prior works

While no code was actually copied from any other project, some of the ideas and APIs of this project were in part derived from or inspired by the following projects.

All due acknowledgement and thanks to the contributors of these projects.

pymarc Copyright (c) 2005-2016 Gabriel Farrell, Mark Matienzo, Geoffrey Spear, Ed Summers

SydneyUniLibrary/marc-transformed