Report maths tweaks (#10604)

* Maths tags updates

- Allow maths operations on non-float values
- Add tests for Decimal values
- Add tests for Money values
- Convert string values to floating point

* Add modulo tag

src/backend/InvenTree/report/templatetags/report.py

@@ -103,7 +103,7 @@ def filter_db_model(model_name: str, **kwargs) -> Optional[QuerySet]:
 def getindex(container: list, index: int) -> Any:
     """Return the value contained at the specified index of the list.
 
-    This function is provideed to get around template rendering limitations.
+    This function is provided to get around template rendering limitations.
 
     Arguments:
         container: A python list object
@@ -413,28 +413,54 @@ def internal_link(link, text) -> str:
     return mark_safe(f'<a href="{url}">{text}</a>')
 
 
-@register.simple_tag()
-def add(x: float, y: float, *args, **kwargs) -> float:
-    """Add two numbers together."""
-    return float(x) + float(y)
+def destringify(value: Any) -> Any:
+    """Convert a string value into a float.
+
+    - If the value is a string, attempt to convert it to a float.
+    - If conversion fails, return the original string.
+    - If the value is not a string, return it unchanged.
+
+    The purpose of this function is to provide "seamless" math operations in templates,
+    where numeric values may be provided as strings, or converted to strings during template rendering.
+    """
+    if isinstance(value, str):
+        value = value.strip()
+        try:
+            return float(value)
+        except ValueError:
+            return value
+
+    return value
 
 
 @register.simple_tag()
-def subtract(x: float, y: float) -> float:
-    """Subtract one number from another."""
-    return float(x) - float(y)
+def add(x: Any, y: Any) -> Any:
+    """Add two numbers (or number like values) together."""
+    return destringify(x) + destringify(y)
 
 
 @register.simple_tag()
-def multiply(x: float, y: float) -> float:
-    """Multiply two numbers together."""
-    return float(x) * float(y)
+def subtract(x: Any, y: Any) -> Any:
+    """Subtract one number (or number-like value) from another."""
+    return destringify(x) - destringify(y)
 
 
 @register.simple_tag()
-def divide(x: float, y: float) -> float:
-    """Divide one number by another."""
-    return float(x) / float(y)
+def multiply(x: Any, y: Any) -> Any:
+    """Multiply two numbers (or number-like values) together."""
+    return destringify(x) * destringify(y)
+
+
+@register.simple_tag()
+def divide(x: Any, y: Any) -> Any:
+    """Divide one number (or number-like value) by another."""
+    return destringify(x) / destringify(y)
+
+
+@register.simple_tag()
+def modulo(x: Any, y: Any) -> Any:
+    """Calculate the modulo of one number (or number-like value) by another."""
+    return destringify(x) % destringify(y)
 
 
 @register.simple_tag

src/backend/InvenTree/report/test_tags.py

@@ -203,9 +203,58 @@ class ReportTagTest(PartImageTestMixin, InvenTreeTestCase):
         self.assertEqual(report_tags.multiply('-2', 4), -8.0)
         self.assertEqual(report_tags.divide(100, 5), 20)
 
+        self.assertEqual(report_tags.modulo(10, 3), 1)
+        self.assertEqual(report_tags.modulo('10', '4'), 2)
+
         with self.assertRaises(ZeroDivisionError):
             report_tags.divide(100, 0)
 
+    def test_maths_tags_with_strings(self):
+        """Tests for mathematical operator tags with string inputs."""
+        self.assertEqual(report_tags.add('10', '20'), 30)
+        self.assertEqual(report_tags.subtract('50.5', '20.2'), 30.3)
+        self.assertEqual(report_tags.multiply(3.0000000000000, '7'), 21)
+        self.assertEqual(report_tags.divide('100.0', '4'), 25.0)
+
+    def test_maths_tags_with_decimal(self):
+        """Tests for mathematical operator tags with Decimal inputs."""
+        from decimal import Decimal
+
+        self.assertEqual(
+            report_tags.add(Decimal('1.1'), Decimal('2.2')), Decimal('3.3')
+        )
+        self.assertEqual(
+            report_tags.subtract(Decimal('5.5'), Decimal('2.2')), Decimal('3.3')
+        )
+        self.assertEqual(report_tags.multiply(Decimal('3.0'), 4), Decimal('12.0'))
+        self.assertEqual(
+            report_tags.divide(Decimal('10.0'), Decimal('2.000')), Decimal('5.0')
+        )
+
+    def test_maths_tags_with_money(self):
+        """Tests for mathematical operator tags with Money inputs."""
+        m1 = Money(100, 'USD')
+        m2 = Money(50, 'USD')
+
+        self.assertEqual(report_tags.add(m1, m2), Money(150, 'USD'))
+        self.assertEqual(report_tags.subtract(m1, m2), Money(50, 'USD'))
+        self.assertEqual(report_tags.multiply(m2, 3), Money(150, 'USD'))
+        self.assertEqual(report_tags.divide(m1, '4'), Money(25, 'USD'))
+
+    def test_maths_tags_invalid(self):
+        """Tests for mathematical operator tags with invalid inputs."""
+        with self.assertRaises(TypeError):
+            report_tags.add('abc', 10)
+
+        with self.assertRaises(TypeError):
+            report_tags.subtract(50, 'xyz')
+
+        with self.assertRaises(TypeError):
+            report_tags.multiply('foo', 'bar')
+
+        with self.assertRaises(TypeError):
+            report_tags.divide('100', 'baz')
+
     def test_number_tags(self):
         """Simple tests for number formatting tags."""
         fn = report_tags.format_number