Temperature units (#6584)

* Update unit conversion

- Set autoconvert_offset_to_baseunit attribute
- Add aliases for common temperature units
- Raise error if invalid target unit is provided

* Updated unit tests

- Checks for temperature conversion
- Checks for invalid units

InvenTree/InvenTree/conversion.py

@@ -36,7 +36,12 @@ def reload_unit_registry():
 
     _unit_registry = None
 
-    reg = pint.UnitRegistry()
+    reg = pint.UnitRegistry(autoconvert_offset_to_baseunit=True)
+
+    # Aliases for temperature units
+    reg.define('@alias degC = celsius = Celsius')
+    reg.define('@alias degF = fahrenheit = Fahrenheit')
+    reg.define('@alias degK = kelvin = Kelvin')
 
     # Define some "standard" additional units
     reg.define('piece = 1')
@@ -142,6 +147,18 @@ def convert_physical_value(value: str, unit: str = None, strip_units=True):
     Returns:
         The converted quantity, in the specified units
     """
+    ureg = get_unit_registry()
+
+    # Check that the provided unit is available in the unit registry
+    if unit:
+        try:
+            valid = unit in ureg
+        except Exception as exc:
+            valid = False
+
+        if not valid:
+            raise ValidationError(_(f'Invalid unit provided ({unit})'))
+
     original = str(value).strip()
 
     # Ensure that the value is a string
@@ -182,8 +199,6 @@ def convert_physical_value(value: str, unit: str = None, strip_units=True):
         else:
             raise ValidationError(_('Invalid quantity supplied'))
 
-    ureg = get_unit_registry()
-
     # Calculate the "magnitude" of the value, as a float
     # If the value is specified strangely (e.g. as a fraction or a dozen), this can cause issues
     # So, we ensure that it is converted to a floating point value

InvenTree/InvenTree/tests.py

@@ -95,6 +95,31 @@ class ConversionTest(TestCase):
             output = InvenTree.conversion.convert_physical_value(val, strip_units=True)
             self.assertAlmostEqual(output, expected, 6)
 
+    def test_temperature_units(self):
+        """Test conversion of temperature units.
+
+        Ref: https://github.com/inventree/InvenTree/issues/6495
+        """
+        tests = [
+            ('3.3°F', '°C', -15.944),
+            ('273°K', '°F', 31.73),
+            ('900', '°C', 900),
+            ('900°F', 'degF', 900),
+            ('900°K', '°C', 626.85),
+            ('800', 'kelvin', 800),
+            ('-100°C', 'fahrenheit', -148),
+            ('-100 °C', 'Fahrenheit', -148),
+            ('-100 Celsius', 'fahrenheit', -148),
+            ('-123.45 fahrenheit', 'kelvin', 186.7888),
+            ('-99Fahrenheit', 'Celsius', -72.7777),
+        ]
+
+        for val, unit, expected in tests:
+            output = InvenTree.conversion.convert_physical_value(
+                val, unit, strip_units=True
+            )
+            self.assertAlmostEqual(output, expected, 3)
+
     def test_base_units(self):
         """Test conversion to specified base units."""
         tests = {