Pint unit fix (#5381)

* Accept conversion of fractional values

- e.g. "1/10" is a valid input value
- pint dimensions returns strange results sometimes

* Add option (default) to return value without units

- Handles conversion for "stringish" input values

* Update unit tests

* Fix return from convert_physical_value method

* Update unit tests

* Improved checking for conversion code

* Call to_base_units first

* Conversion depends on whether units are supplied or not

* Updates to unit testing

* Handle conversion of units for supplier parts

- Includes some refactoring

InvenTree/InvenTree/conversion.py

@@ -70,12 +70,13 @@ def reload_unit_registry():
     return reg
 
 
-def convert_physical_value(value: str, unit: str = None):
+def convert_physical_value(value: str, unit: str = None, strip_units=True):
     """Validate that the provided value is a valid physical quantity.
 
     Arguments:
         value: Value to validate (str)
         unit: Optional unit to convert to, and validate against
+        strip_units: If True, strip units from the returned value, and return only the dimension
 
     Raises:
         ValidationError: If the value is invalid or cannot be converted to the specified unit
@@ -100,7 +101,7 @@ def convert_physical_value(value: str, unit: str = None):
 
         if unit:
 
-            if val.units == ureg.dimensionless:
+            if is_dimensionless(val):
                 # If the provided value is dimensionless, assume that the unit is correct
                 val = ureg.Quantity(value, unit)
             else:
@@ -109,19 +110,65 @@ def convert_physical_value(value: str, unit: str = None):
 
         # At this point we *should* have a valid pint value
         # To double check, look at the maginitude
-        float(val.magnitude)
+        float(ureg.Quantity(val.magnitude).magnitude)
     except (TypeError, ValueError, AttributeError):
         error = _('Provided value is not a valid number')
     except (pint.errors.UndefinedUnitError, pint.errors.DefinitionSyntaxError):
         error = _('Provided value has an invalid unit')
-    except pint.errors.DimensionalityError:
-        error = _('Provided value could not be converted to the specified unit')
-
-    if error:
         if unit:
             error += f' ({unit})'
 
+    except pint.errors.DimensionalityError:
+        error = _('Provided value could not be converted to the specified unit')
+        if unit:
+            error += f' ({unit})'
+
+    except Exception as e:
+        error = _('Error') + ': ' + str(e)
+
+    if error:
         raise ValidationError(error)
 
-    # Return the converted value
-    return val
+    # 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 isuses
+    # So, we ensure that it is converted to a floating point value
+    # If we wish to return a "raw" value, some trickery is required
+    if unit:
+        magnitude = ureg.Quantity(val.to(unit)).magnitude
+    else:
+        magnitude = ureg.Quantity(val.to_base_units()).magnitude
+
+    magnitude = float(ureg.Quantity(magnitude).to_base_units().magnitude)
+
+    if strip_units:
+        return magnitude
+    elif unit or val.units:
+        return ureg.Quantity(magnitude, unit or val.units)
+    else:
+        return ureg.Quantity(magnitude)
+
+
+def is_dimensionless(value):
+    """Determine if the provided value is 'dimensionless'
+
+    A dimensionless value might look like:
+
+    0.1
+    1/2 dozen
+    three thousand
+    1.2 dozen
+    (etc)
+    """
+    ureg = get_unit_registry()
+
+    # Ensure the provided value is in the right format
+    value = ureg.Quantity(value)
+
+    if value.units == ureg.dimensionless:
+        return True
+
+    if value.to_base_units().units == ureg.dimensionless:
+        return True
+
+    # At this point, the value is not dimensionless
+    return False

InvenTree/InvenTree/tests.py

@@ -42,6 +42,26 @@ from .validators import validate_overage
 class ConversionTest(TestCase):
     """Tests for conversion of physical units"""
 
+    def test_base_units(self):
+        """Test conversion to specified base units"""
+        tests = {
+            "3": 3,
+            "3 dozen": 36,
+            "50 dozen kW": 600000,
+            "1 / 10": 0.1,
+            "1/2 kW": 500,
+            "1/2 dozen kW": 6000,
+            "0.005 MW": 5000,
+        }
+
+        for val, expected in tests.items():
+            q = InvenTree.conversion.convert_physical_value(val, 'W')
+
+            self.assertAlmostEqual(q, expected, 0.01)
+
+            q = InvenTree.conversion.convert_physical_value(val, 'W', strip_units=False)
+            self.assertAlmostEqual(float(q.magnitude), expected, 0.01)
+
     def test_dimensionless_units(self):
         """Tests for 'dimensonless' unit quantities"""
 
@@ -54,11 +74,21 @@ class ConversionTest(TestCase):
             '3 hundred': 300,
             '2 thousand': 2000,
             '12 pieces': 12,
+            '1 / 10': 0.1,
+            '1/2': 0.5,
+            '-1 / 16': -0.0625,
+            '3/2': 1.5,
+            '1/2 dozen': 6,
         }
 
         for val, expected in tests.items():
-            q = InvenTree.conversion.convert_physical_value(val).to_base_units()
-            self.assertEqual(q.magnitude, expected)
+            # Convert, and leave units
+            q = InvenTree.conversion.convert_physical_value(val, strip_units=False)
+            self.assertAlmostEqual(float(q.magnitude), expected, 0.01)
+
+            # Convert, and strip units
+            q = InvenTree.conversion.convert_physical_value(val)
+            self.assertAlmostEqual(q, expected, 0.01)
 
     def test_invalid_values(self):
         """Test conversion of invalid inputs"""
@@ -71,11 +101,19 @@ class ConversionTest(TestCase):
             '--',
             '+',
             '++',
+            '1/0',
+            '1/-',
         ]
 
         for val in inputs:
+            # Test with a provided unit
             with self.assertRaises(ValidationError):
-                InvenTree.conversion.convert_physical_value(val)
+                InvenTree.conversion.convert_physical_value(val, 'meter')
+
+            # Test dimensionless
+            with self.assertRaises(ValidationError):
+                result = InvenTree.conversion.convert_physical_value(val)
+                print("Testing invalid value:", val, result)
 
     def test_custom_units(self):
         """Tests for custom unit conversion"""
@@ -104,8 +142,23 @@ class ConversionTest(TestCase):
         reg['hpmm']
 
         # Convert some values
-        q = InvenTree.conversion.convert_physical_value('1 hpmm', 'henry / km')
-        self.assertEqual(q.magnitude, 1000000)
+        tests = {
+            '1': 1,
+            '1 hpmm': 1000000,
+            '1 / 10 hpmm': 100000,
+            '1 / 100 hpmm': 10000,
+            '0.3 hpmm': 300000,
+            '-7hpmm': -7000000,
+        }
+
+        for val, expected in tests.items():
+            # Convert, and leave units
+            q = InvenTree.conversion.convert_physical_value(val, 'henry / km', strip_units=False)
+            self.assertAlmostEqual(float(q.magnitude), expected, 0.01)
+
+            # Convert and strip units
+            q = InvenTree.conversion.convert_physical_value(val, 'henry / km')
+            self.assertAlmostEqual(q, expected, 0.01)
 
 
 class ValidatorTest(TestCase):

InvenTree/company/models.py

@@ -638,11 +638,12 @@ class SupplierPart(MetadataMixin, InvenTreeBarcodeMixin, common.models.MetaMixin
             try:
                 # Attempt conversion to specified unit
                 native_value = InvenTree.conversion.convert_physical_value(
-                    self.pack_quantity, self.part.units
+                    self.pack_quantity, self.part.units,
+                    strip_units=False
                 )
 
                 # If part units are not provided, value must be dimensionless
-                if not self.part.units and native_value.units not in ['', 'dimensionless']:
+                if not self.part.units and not InvenTree.conversion.is_dimensionless(native_value):
                     raise ValidationError({
                         'pack_quantity': _("Pack units must be compatible with the base part units")
                     })

InvenTree/part/models.py

@@ -3576,8 +3576,7 @@ class PartParameter(MetadataMixin, models.Model):
 
         if self.template.units:
             try:
-                converted = InvenTree.conversion.convert_physical_value(self.data, self.template.units)
-                self.data_numeric = float(converted.magnitude)
+                self.data_numeric = InvenTree.conversion.convert_physical_value(self.data, self.template.units)
             except (ValidationError, ValueError):
                 self.data_numeric = None