Module: GTIN

Included in:
String
Defined in:
lib/gtin_extras/gtin.rb

Overview

String validation and manipulation for GTIN/EAN/GS1

Instance Method Summary collapse

Instance Method Details

#calculate_check_digit ⇒ Object

FOR A UPC: Ref: www.gs1.org/services/how-calculate-check-digit-manually Ref: www.gtin.info/check-digit-calculator/



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# File 'lib/gtin_extras/gtin.rb', line 40

def calculate_check_digit
  factor = 3
  sum = 0
  (0..(length - 1)).reverse_each do |i|
    sum += self[i].chr.to_i * factor
    factor = 4 - factor
  end
  (1000 - sum) % 10
end

#coerce_to_upc ⇒ Object 



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# File 'lib/gtin_extras/gtin.rb', line 93

def coerce_to_upc
  return self if upc?
  return unless only_gtin_digits?
  if gtin_structure == :gs1
    new_upc = to_gtin(12)
    return new_upc if new_upc.upc?
  end
  if length == 10
    new_upc = "#{to_gtin(11)}#{us_upc_checksum}"
    return new_upc if new_upc.upc?
  end
  return unless length == 11
  new_gtin_us = to_gtin(12) # assumes US-based UPC
  new_gtin_wc = "#{self}#{us_upc_checksum}"
  return nil if new_gtin_wc.upc? && new_gtin_us.upc? # avoid conflict
  return new_gtin_us if new_gtin_us.upc?
  return new_gtin_wc if new_gtin_wc.upc?
  nil
end

#ean? ⇒ Boolean Also known as: gln?, ucc?

Returns:

  • (Boolean) 


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# File 'lib/gtin_extras/gtin.rb', line 10

def ean?
  return false unless only_gtin_digits?
  case length
  when 13
    self[12] == self[0..11].calculate_check_digit.to_s
  when 8
    self[7] == self[0..6].calculate_check_digit.to_s
  else
    false
  end
end

#gs1? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gtin_extras/gtin.rb', line 24

def gs1?
  return false if length != 14
  return false unless only_gtin_digits?
  self[13] == self[0..12].calculate_check_digit.to_s
end

#gtin_structure ⇒ Object 



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# File 'lib/gtin_extras/gtin.rb', line 3

def gtin_structure
  return :upc if upc?
  return :ean if ean?
  return :gs1 if gs1?
  nil
end

#only_gtin_digits? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gtin_extras/gtin.rb', line 85

def only_gtin_digits?
  return unless length > 1
  (0..(length - 1)).reverse_each do |i|
    return nil unless self[i].chr.to_i.to_s == self[i].chr
  end
  true
end

#to_gtin(size = 14) ⇒ Object 



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# File 'lib/gtin_extras/gtin.rb', line 81

def to_gtin(size = 14)
  "%0#{size.to_i}d" % to_s.gsub(/[\D]+/, '').to_i
end

#to_gtin_12 ⇒ Object Also known as: to_upc, to_upc_a

GTIN-12 (UPC-A): this is a 12-digit number used primarily in North America



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# File 'lib/gtin_extras/gtin.rb', line 55

def to_gtin_12
  to_gtin(12)
end

#to_gtin_13 ⇒ Object Also known as: to_ean_13, to_ucc_13, to_ean

GTIN-13 (EAN/UCC-13): this is a 13-digit number used predominately outside of North America



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# File 'lib/gtin_extras/gtin.rb', line 69

def to_gtin_13
  to_gtin(13)
end

#to_gtin_14 ⇒ Object

GTIN-14 (EAN/UCC-14 or ITF-14): this is a 14-digit number used to identify trade items at various packaging levels



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# File 'lib/gtin_extras/gtin.rb', line 77

def to_gtin_14
  to_gtin(14)
end

#to_gtin_8 ⇒ Object Also known as: to_ean_8, to_ucc_8

GTIN-8 (EAN/UCC-8): this is an 8-digit number used primarily outside of North America



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# File 'lib/gtin_extras/gtin.rb', line 62

def to_gtin_8
  to_gtin(8)
end

#upc? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gtin_extras/gtin.rb', line 30

def upc?
  return false if length != 12
  return false unless only_gtin_digits?
  self[11] == self[0..10].calculate_check_digit.to_s
end

#us_upc_checksum ⇒ Object 



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# File 'lib/gtin_extras/gtin.rb', line 50

def us_upc_checksum
  to_gtin(11).calculate_check_digit
end