Method: MARC::Writer.encode

Defined in:
lib/marc/writer.rb

.encode(record, allow_oversized = false) ⇒ Object

a static method that accepts a MARC::Record object and returns the record encoded as MARC21 in transmission format

Second arg allow_oversized, default false, set to true to raise on MARC record that can’t fit into ISO 2709.



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# File 'lib/marc/writer.rb', line 64

def self.encode(record, allow_oversized = false)
  directory = ""
  fields = ""
  offset = 0
  record.each do |field|
    # encode the field
    field_data = ""
    if field.instance_of?(MARC::DataField)
      warn("Warn:  Missing indicator") unless field.indicator1 && field.indicator2
      field_data = (field.indicator1 || " ") + (field.indicator2 || " ")
      field.subfields.each do |s|
        field_data += SUBFIELD_INDICATOR + s.code + s.value
      end
    elsif field.instance_of?(MARC::ControlField)
      field_data = field.value
    end
    field_data += END_OF_FIELD

    # calculate directory entry for the field
    field_length = (field_data.respond_to?(:bytesize) ?
                      field_data.bytesize :
                      field_data.length)
    directory += sprintf("%03s", field.tag) + format_byte_count(field_length, allow_oversized, 4) + format_byte_count(offset, allow_oversized)

    # add field to data for other fields
    fields += field_data

    # update offset for next field
    offset += field_length
  end

  # determine the base (leader + directory)
  base = record.leader + directory + END_OF_FIELD

  # determine complete record
  marc = base + fields + END_OF_RECORD

  # update leader with the byte offest to the end of the directory
  bytesize = base.respond_to?(:bytesize) ? base.bytesize() : base.length
  marc[12..16] = format_byte_count(bytesize, allow_oversized)

  # update the record length
  bytesize = marc.respond_to?(:bytesize) ? marc.bytesize() : marc.length
  marc[0..4] = format_byte_count(bytesize, allow_oversized)

  # store updated leader in the record that was passed in
  record.leader = marc[0..LEADER_LENGTH - 1]

  # return encoded marc
  marc
end