Fix #471: Validate GS1-128 AIs for trade measures (31nn, 32nn, 35nn, 36nn)

Author: Adrià Tarroja Caubet

stdnum/gs1_128.py

@@ -75,6 +75,10 @@
     '8007': 'stdnum.iban',
 }
 
+_TRADE_MEASURE_PREFIXES = {
+    '31', '32', '35', '36',
+}
+
 
 def compact(number: str) -> str:
     """Convert the GS1-128 to the minimal representation.
@@ -195,6 +199,9 @@ def info(number: str, separator: str = '') -> dict[str, Any]:
     If a `separator` is provided it will be used as FNC1 to determine the end
     of variable-sized values.
     """
+    for grp in re.findall(r"\((\d+)\)", number):
+        if grp[:2] in _TRADE_MEASURE_PREFIXES and len(grp) != 4:
+            raise InvalidComponent()
     number = compact(number)
     data = {}
     identifier = ''
@@ -253,7 +260,14 @@ def encode(data: Mapping[str, object], separator: str = '', parentheses: bool =
         if ai in _ai_validators:
             mod = __import__(_ai_validators[ai], globals(), locals(), ['validate'])
             mod.validate(value)
-        value = _encode_value(info['format'], info['type'], value)
+        raw = _encode_value(info['format'], info['type'], value)
+        if info['type'] == 'decimal' and info['format'] == 'N6' and ai[:2] in _TRADE_MEASURE_PREFIXES:
+            # insert decimal count into AI and drop it from the value payload
+            dec = raw[0]
+            ai = ai + dec
+            value = raw[1:]
+        else:
+            value = raw
         # store variable-sized values separate from fixed-size values
         if info.get('fnc1'):
             variable_values.append((ai_fmt % ai, info['format'], info['type'], value))

tests/test_gs1_128.doctest

@@ -65,7 +65,7 @@ properly.
 ...     '313': '123.456',  # str
 ...     '391': ('123', Decimal('123.456')),  # currency number combo
 ... }, parentheses=True)
-'(310)2001723(311)0000456(312)5033333(313)3123456(391)3123123456'
+'(3102)001723(3110)000456(3125)033333(3133)123456(391)3123123456'
 
 We generate dates in various formats, depending on the AI.
 
@@ -88,6 +88,8 @@ We generate dates in various formats, depending on the AI.
 '(7011)181119'
 >>> gs1_128.encode({'7011': datetime.datetime(2018, 11, 19, 12, 45)}, parentheses=True)
 '(7011)1811191245'
+>>> gs1_128.encode({'01': '98456789014533', '310': Decimal('0.035')}, parentheses=True)
+'(01)98456789014533(3103)000035'
 
 If we try to encode an invalid EAN we will get an error.
 
@@ -104,7 +106,7 @@ pprint.pprint(gs1_128.info('(01)38425876095074(17)181119(37)1 '))
 {'01': '38425876095074', '17': datetime.date(2018, 11, 19), '37': 1}
 >>> pprint.pprint(gs1_128.info('013842587609507417181119371'))
 {'01': '38425876095074', '17': datetime.date(2018, 11, 19), '37': 1}
->>> pprint.pprint(gs1_128.info('(02)98412345678908(310)3017230(37)32'))
+>>> pprint.pprint(gs1_128.info('(02)98412345678908(3103)017230(37)32'))
 {'02': '98412345678908', '310': Decimal('17.230'), '37': 32}
 >>> pprint.pprint(gs1_128.info('(01)58425876097843(10)123456              (17)181119(37)18'))
 {'01': '58425876097843', '10': '123456', '17': datetime.date(2018, 11, 19), '37': 18}
@@ -124,8 +126,16 @@ InvalidComponent: ...
 We can decode decimal values from various formats.
 
 >>> pprint.pprint(gs1_128.info('(310)5033333'))
+Traceback (most recent call last):
+    ...
+InvalidComponent: ...
+>>> pprint.pprint(gs1_128.info('(3105)033333'))
+{'310': Decimal('0.33333')}
+>>> pprint.pprint(gs1_128.info('(01)98456789014533(3103)000035'))
+{'01': '98456789014533', '310': Decimal('0.035')}
+>>> pprint.pprint(gs1_128.info('(3105)033333'))
 {'310': Decimal('0.33333')}
->>> pprint.pprint(gs1_128.info('(310)0033333'))
+>>> pprint.pprint(gs1_128.info('(3100)033333'))
 {'310': Decimal('33333')}
 >>> pprint.pprint(gs1_128.info('(391)3123123456'))
 {'391': ('123', Decimal('123.456'))}