ruby-marc code sample

def marc_record(textbook)
  # Generate a MARC record with a leader
  record = MARC::Record.new() 

  # Leader example:
  # *00-04 Record length computed automatically
  record.leader[5] = "n"
  record.leader[6] = "a"
  record.leader[7] = "i"
  record.leader[9] = "a"

  # ...
  
  # Control Field (00#) example:
  # *008
  # 00-05 Date of creation, 06 Type of publication date, 07-10 Date 1, 11-14 Date 2, 15-17 Country of publication code, 35-37 Language of publication code
  record.append(MARC::ControlField.new('008', textbook.created_at.strftime('%y%m%d') + "c" + (textbook.copyright_year ? textbook.copyright_year.to_s : "0000") + "9999" + "mnu" + "                 " + textbook.language + "  ") ) 

  # ...
  
  
  # Data Field examples:
  
  # *050: Library of Congress Call Number
  # *$a: Classification number (R)
  # $b: Item number (NR)
  textbook.subjects.pluck(:call_number).uniq.compact.each do |call_number|
    loc_field = MARC::DataField.new('050', ' ', '4') # First indicator: 0/1/# if in Library of Congress collection (blank is unknown). Second indicator: 0/4 call number assigned by LC or other (respectively)
    loc_field.subfields << MARC::Subfield.new('a', call_number)
    record.append(loc_field)
  end

  # 336: Content Type
  # $a: Content type term
  # $b: Content type code
  # $2: Code source 
  content_record = MARC::DataField.new('336') # No indicators
  content_record.subfields << MARC::Subfield.new('a', "text")
  content_record.subfields << MARC::Subfield.new('b', "txt")
  content_record.subfields << MARC::Subfield.new('2', "rdacontent")
  record.append(content_record)

  record
end

def generate_marc(textbooks)
  writer = MARC::Writer.new("path/to/file.mrc")
  textbooks.each do |t|
    writer.write(marc_record(t))
  end
  writer.close
end