[API] Bug fix for PartCategory cascade filter (#11562)

* Bug fix for PartCategory cascade filter

* Additional unit test

src/backend/InvenTree/part/api.py

@@ -161,7 +161,7 @@ class CategoryFilter(FilterSet):
 
         Note: If the "parent" filter is provided, we offload the logic to that method.
         """
-        parent = str2bool(self.data.get('parent', None))
+        parent = self.data.get('parent', None)
         top_level = str2bool(self.data.get('top_level', None))
 
         # If the parent is *not* provided, update the results based on the "cascade" value

src/backend/InvenTree/part/test_api.py

@@ -111,7 +111,7 @@ class PartCategoryAPITest(InvenTreeAPITestCase):
         url = reverse('api-part-category-list')
 
         # star categories manually for tests as it is not possible with fixures
-        # because the current user is not fixured itself and throws an invalid
+        # because the current user is not fixtured itself and throws an invalid
         # foreign key constraint
         for pk in [3, 4]:
             PartCategory.objects.get(pk=pk).set_starred(self.user, True)
@@ -812,9 +812,14 @@ class PartAPITest(PartAPITestBase):
 
         # Children of PartCategory<1>, do not cascade
         response = self.get(url, {'parent': 1, 'cascade': 'false'})
-
         self.assertEqual(len(response.data), 3)
 
+        # Children of PartCategory<7>, with or without cascade
+        # Only 1 child in either case
+        for cascade in ['true', 'false']:
+            response = self.get(url, {'parent': 7, 'cascade': cascade})
+            self.assertEqual(len(response.data), 1)
+
     def test_add_categories(self):
         """Check that we can add categories."""
         data = {'name': 'Animals', 'description': 'All animals go here'}
@@ -1644,7 +1649,7 @@ class PartCreationTests(PartAPITestBase):
 
         self.assertEqual(cat.parameter_templates.count(), 3)
 
-        # Creat a new Part, without copying category parameters
+        # Create a new Part, without copying category parameters
         data = self.post(
             reverse('api-part-list'),
             {
@@ -2314,7 +2319,7 @@ class PartAPIAggregationTest(InvenTreeAPITestCase):
         self.assertEqual(data['allocated_to_build_orders'], 0)
         self.assertEqual(data['allocated_to_sales_orders'], 0)
 
-        # The unallocated stock count should equal the 'in stock' coutn
+        # The unallocated stock count should equal the 'in stock' count
         in_stock = data['in_stock']
         self.assertEqual(in_stock, 126)
         self.assertEqual(data['unallocated_stock'], in_stock)