find_duplicate_fields.rb

require_relative './../lib/marc_cleanup'

def duplicate_fields?(record) #creates an array with each unique field value converted to a string
  field_array = []
  record.fields.each do |field|
    return true if field_array.include?(field.to_s)
    field_array << field.to_s
  end
  false
end
 
writer = MARC::XMLWriter.new('filepath')
Dir.glob('filepath').each do |file|
  puts File.basename(file)
  reader = MARC::XMLReader.new(file, parser: 'magic', ignore_namespace: true)
  reader.each do |record|
    if duplicate_fields?(record)
      writer.write(record) 
    end
  end
end
writer.close