marc4j4r

A ruby wrapper around the marc4j.jar (as forked by javamarc) java library for dealing with library MARC data.

Note: rdoc.info doesn’t do a great job with this; I think it’s getting confused by the java stuff. Here’s a list of links for all the classes:

Getting a MARC reader

marc4j4r provides three readers out of the box: :strictmarc (binary), :permissivemarc (:binary), :marcxml (MARC-XML), or :alephsequential (Ex Libris’s AlephSequential format).

You can pass either a filename or an open IO object (either ruby or java.io.inputstream)

require 'marc4j4r'

binreader = MARC4J4R::Reader.new('test.mrc') # defaults to :strictmarc
binreader = MARC4J4R::Reader.new('test.mrc', :strictmarc)

permissivereader =  MARC4J4R::Reader.new('test.mrc', :permissivemarc)

xmlreader = MARC4J4R::Reader.new('test.xml', :marcxml)
asreader = MARC4J4R::Reader.new('test.seq', :alephsequential)

# Or use a file object

reader = MARC4J4R::Reader.new(File.open('test.mrc'))

# Or a java.io.inputstream

jurl = Java::java.net.URL.new('http://my.machine.com/test.mrc')
istream = jurl.openConnection.getInputStream
reader = MARC4J4R::Reader.new(istream)

Using the reader

A MARC4J4R::Reader is an Enumerable, so you can do:

reader.each do |record|
  # do stuff with the record
end

Or, if you’re using threach:

reader.threach(2) do |record|
  # do stuff with records in two threads
end

Using the writer

binaryWriter = MARC4J4R::Writer.new(filename, :strictmarc)
xmlWriter    = MARC4J4R::Writer.new(filename, :marcxml)

writer.write(record)
# repeat
writer.close

Working with records and fields

In addition to all the normal marc4j methods, MARC4J4R::Record exposes some additional methods and syntaxes.

See the classes themselves and/or the specs for more examples.

MARC4J4R::Reader
MARC4J4R::Writer
MARC4J4R::Record
MARC4J4R::ControlField
MARC4J4R::DataField

MARC4J4R::SubField

leader = record.leader

# All fields are available via #each or #fields

fields = record.fields

record.each do |field|
  # do something with each controlfield/datafield; returned in the order they were added
end

# Controlfields have a tag and a value

idfield = record['001']
idfield.tag # => '001'
id = idfield.value # or idfield.data, same thing

# Get the first datafield with a given tag
first700 = record['700'] # Note: need to use strings, not integers

# Stringify a field to get all the subfields joined with spaces

fullTitle = record['245'].to_s

all700s  = record.find_by_tag '700'
all700and856s = record.find_by_tag ['700', '856']

# Construct and add a controlfield
record << MARC4J4R::ControlField.new('001', '0000333234')

# Construct and add a datafield
df = MARC4J4R::DataField.new(tag, ind1, ind2)

ind1 = df.ind1
ind2 = df.ind2

df << MARC4J4R::Subfield.new('a', 'the $a value')
df << MARC4J4R::Subfield.new('b', 'the $b value')   

# Add it to a record

record << df

# Get subfields or their values

firstSubfieldAValue = df['a']

allSubfields = df.subs
allSubfieldAs = df.subs('a')
allSubfieldAorBs = df.subs(['a', 'b'])

allSubfieldAorBValues = df.sub_values(['a', 'b'])

Note on Patches/Pull Requests