Add function to "increment" a number or a number-like string

- Observe string width
- Keep prefix if one exists

InvenTree/InvenTree/helpers.py

@@ -120,6 +120,59 @@ def normalize(d):
     return d.quantize(Decimal(1)) if d == d.to_integral() else d.normalize()
 
 
+def increment(n):
+    """
+    Attempt to increment an integer (or a string that looks like an integer!)
+    
+    e.g.
+
+    001 -> 002
+    2 -> 3
+    AB01 -> AB02
+    QQQ -> QQQ
+    
+    """
+
+    value = str(n).strip()
+
+    # Ignore empty strings
+    if not value:
+        return value
+
+    pattern = r"(.*?)(\d+)?$"
+
+    result = re.search(pattern, value)
+
+    # No match!
+    if result is None:
+        return value
+
+    groups = result.groups()
+
+    # If we cannot match the regex, then simply return the provided value
+    if not len(groups) == 2:
+        return value
+
+    prefix, number = groups
+
+    # No number extracted? Simply return the prefix (without incrementing!)
+    if not number:
+        return prefix
+
+    # Record the width of the number
+    width = len(number)
+
+    try:
+        number = int(number) + 1
+        number = str(number)
+    except ValueError:
+        pass
+
+    number = number.zfill(width)
+
+    return prefix + number
+
+
 def decimal2string(d):
     """
     Format a Decimal number as a string,

InvenTree/InvenTree/tests.py

@@ -108,6 +108,29 @@ class TestQuoteWrap(TestCase):
         self.assertEqual(helpers.WrapWithQuotes('hello"'), '"hello"')
 
 
+class TestIncrement(TestCase):
+
+    def tests(self):
+        """ Test 'intelligent' incrementing function """
+
+        tests = [
+            ("", ""),
+            (1, "2"),
+            ("001", "002"),
+            ("1001", "1002"),
+            ("ABC123", "ABC124"),
+            ("XYZ0", "XYZ1"),
+            ("123Q", "123Q"),
+            ("QQQ", "QQQ"),
+        ]
+
+        for test in tests:
+            a, b = test
+
+            result = helpers.increment(a)
+            self.assertEqual(result, b)
+
+
 class TestMakeBarcode(TestCase):
     """ Tests for barcode string creation """