[PUI] Category params (#6767)

* Validate default value field for PartCategoryParameterTemplate

- Only if unit checks are enforced
- Only if default value is not blank

* Add basic table for part category parameter templates

* Add functions to create / edit / delete via table

* Fix unit testing

InvenTree/part/models.py

@@ -3833,6 +3833,28 @@ class PartCategoryParameterTemplate(InvenTree.models.InvenTreeMetadataModel):
             return f'{self.category.name} | {self.parameter_template.name} | {self.default_value}'
         return f'{self.category.name} | {self.parameter_template.name}'
 
+    def clean(self):
+        """Validate this PartCategoryParameterTemplate instance.
+
+        Checks the provided 'default_value', and (if not blank), ensure it is valid.
+        """
+        super().clean()
+
+        self.default_value = (
+            '' if self.default_value is None else str(self.default_value.strip())
+        )
+
+        if self.default_value and InvenTreeSetting.get_setting(
+            'PART_PARAMETER_ENFORCE_UNITS', True, cache=False, create=False
+        ):
+            if self.parameter_template.units:
+                try:
+                    InvenTree.conversion.convert_physical_value(
+                        self.default_value, self.parameter_template.units
+                    )
+                except ValidationError as e:
+                    raise ValidationError({'default_value': e.message})
+
     category = models.ForeignKey(
         PartCategory,
         on_delete=models.CASCADE,

InvenTree/part/test_api.py

@@ -196,6 +196,11 @@ class PartCategoryAPITest(InvenTreeAPITestCase):
         # Add some more category templates via the API
         n = PartParameterTemplate.objects.count()
 
+        # Ensure validation of parameter values is disabled for these checks
+        InvenTreeSetting.set_setting(
+            'PART_PARAMETER_ENFORCE_UNITS', False, change_user=None
+        )
+
         for template in PartParameterTemplate.objects.all():
             response = self.post(
                 url,