CreateSalesOrderLineItem: auto-apply sales price based on part price_breaks, currency, and quantity (#10549)

* updated part api mixin and part serializer to include salepricebreaks when explicitly queried

* fixed bug in ApiForm that prevents form field value from updating correctly

* CreateSalesOrderLineItem form now automatically applies price break based on currency and quantity for a part

* bumped API version due to PartsList api price_breaks query param

* fixed incorrect field names

* Remove whitespace

* Increase database query limit from 20 to 25

* updated ApiForm to propagate false and 0 as values to their respective fields, updated ApiFormField to eagerly apply AdjustValue to apply adjustments when onChange does not fire (when the value does not truly change)

* updated pagination number check to a range instead of discreet values.

---------

Co-authored-by: Matthias Mair <code@mjmair.com>
Co-authored-by: Oliver <oliver.henry.walters@gmail.com>

src/backend/InvenTree/InvenTree/api_version.py

@@ -1,12 +1,15 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 411
+INVENTREE_API_VERSION = 412
 
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 INVENTREE_API_TEXT = """
 
+v412 -> 2025-10-19 : https://github.com/inventree/InvenTree/pull/10549
+    - added a new query parameter for the PartsList api: price_breaks (default: false)
+
 v411 -> 2025-06-19 : https://github.com/inventree/InvenTree/pull/10630
     - Editorialy changes to machine api - no functional changes
 

src/backend/InvenTree/part/api.py

@@ -1022,6 +1022,9 @@ class PartMixin(SerializerContextMixin):
         if str2bool(self.request.query_params.get('parameters', False)):
             queryset = queryset.prefetch_related('parameters', 'parameters__template')
 
+        if str2bool(self.request.query_params.get('price_breaks', True)):
+            queryset = queryset.prefetch_related('salepricebreaks')
+
         return queryset
 
     def get_serializer(self, *args, **kwargs):
@@ -1061,6 +1064,7 @@ class PartOutputOptions(OutputConfiguration):
         InvenTreeOutputOption('category_detail'),
         InvenTreeOutputOption('location_detail'),
         InvenTreeOutputOption('path_detail'),
+        InvenTreeOutputOption('price_breaks'),
     ]
 
 

src/backend/InvenTree/part/serializers.py

@@ -213,10 +213,14 @@ class PartTestTemplateSerializer(
 
 @register_importer()
 class PartSalePriceSerializer(
-    DataImportExportSerializerMixin, InvenTree.serializers.InvenTreeModelSerializer
+    InvenTree.serializers.FilterableSerializerMixin,
+    DataImportExportSerializerMixin,
+    InvenTree.serializers.InvenTreeModelSerializer,
 ):
     """Serializer for sale prices for Part model."""
 
+    no_filters = True
+
     class Meta:
         """Metaclass defining serializer fields."""
 
@@ -692,6 +696,7 @@ class PartSerializer(
             'pricing_max',
             'pricing_updated',
             'responsible',
+            'price_breaks',
             # Annotated fields
             'allocated_to_build_orders',
             'allocated_to_sales_orders',
@@ -731,6 +736,7 @@ class PartSerializer(
         create = kwargs.pop('create', False)
         # pricing = kwargs.pop('pricing', True)
         # path_detail = kwargs.pop('path_detail', False)
+        # price_breaks = kwargs.pop('price_breaks', False)
 
         super().__init__(*args, **kwargs)
 
@@ -750,6 +756,9 @@ class PartSerializer(
         if not path_detail:
             self.fields.pop('category_path', None)
 
+        if not price_breaks:
+            self.fields.pop('price_breaks', None)
+
         if not pricing:
             self.fields.pop('pricing_min', None)
             self.fields.pop('pricing_max', None)
@@ -1032,6 +1041,12 @@ class PartSerializer(
         PartParameterSerializer(many=True, read_only=True, allow_null=True)
     )
 
+    price_breaks = enable_filter(
+        PartSalePriceSerializer(source='salepricebreaks', many=True, read_only=True),
+        False,
+        filter_name='price_breaks',
+    )
+
     # Extra fields used only for creation of a new Part instance
     duplicate = DuplicatePartSerializer(
         label=_('Duplicate Part'),

src/backend/InvenTree/part/test_api.py

@@ -32,6 +32,7 @@ from part.models import (
     PartParameter,
     PartParameterTemplate,
     PartRelated,
+    PartSellPriceBreak,
     PartTestTemplate,
 )
 from stock.models import StockItem, StockLocation
@@ -2059,8 +2060,8 @@ class PartListTests(PartAPITestBase):
             with CaptureQueriesContext(connection) as ctx:
                 self.get(url, query, expected_code=200)
 
-            # No more than 20 database queries
+            # No more than 25 database queries
-            self.assertLess(len(ctx), 20)
+            self.assertLess(len(ctx), 25)
 
         # Test 'category_detail' annotation
         for b in [False, True]:
@@ -2076,6 +2077,80 @@ class PartListTests(PartAPITestBase):
             # No more than 20 DB queries
             self.assertLessEqual(len(ctx), 20)
 
+    def test_price_breaks(self):
+        """Test that price_breaks parameter works correctly and efficiently."""
+        url = reverse('api-part-list')
+
+        # Create some parts with sale price breaks
+        for i in range(5):
+            part = Part.objects.create(
+                name=f'Part with breaks {i}',
+                description='A part with sale price breaks',
+                category=PartCategory.objects.first(),
+                salable=True,
+            )
+
+            # Create multiple price breaks for each part
+            for qty, price in [(1, 10 + i), (10, 9 + i), (100, 8 + i)]:
+                PartSellPriceBreak.objects.create(
+                    part=part, quantity=qty, price=price, price_currency='USD'
+                )
+
+        # Test 1: Without price_breaks parameter (default is False, field should not be included)
+        response = self.get(
+            url, {'limit': 5, 'search': 'Part with breaks'}, expected_code=200
+        )
+
+        self.assertEqual(len(response.data['results']), 5)
+        first_result = response.data['results'][0]
+        self.assertNotIn('price_breaks', first_result)
+
+        # Test 2: Explicitly with price_breaks=false
+        with CaptureQueriesContext(connection) as ctx:
+            response = self.get(
+                url,
+                {'limit': 5, 'price_breaks': False, 'search': 'Part with breaks'},
+                expected_code=200,
+            )
+
+        first_result = response.data['results'][0]
+        self.assertNotIn('price_breaks', first_result)
+
+        query_count_without_price_breaks = len(ctx)
+
+        # Test 3: Explicitly with price_breaks=true
+        with CaptureQueriesContext(connection) as ctx:
+            response = self.get(
+                url,
+                {'limit': 5, 'price_breaks': True, 'search': 'Part with breaks'},
+                expected_code=200,
+            )
+
+        # Should have price_breaks field with data
+        for result in response.data['results']:
+            self.assertIn('price_breaks', result)
+            self.assertIsInstance(result['price_breaks'], list)
+            self.assertEqual(len(result['price_breaks']), 3)
+
+            for pb in result['price_breaks']:
+                self.assertIn('pk', pb)
+                self.assertIn('quantity', pb)
+                self.assertIn('price', pb)
+                self.assertIn('price_currency', pb)
+
+        # Make sure there's no n+1 query problem
+        query_count_with_price_breaks = len(ctx)
+        query_difference = (
+            query_count_with_price_breaks - query_count_without_price_breaks
+        )
+
+        # There are 2 additional queries, 1 for the salepricebreak subselect and 1 for Currency codes because of InvenTreeCurrencySerializer
+        self.assertLessEqual(
+            query_difference,
+            2,
+            f'Query count difference too high: {query_difference} (with: {query_count_with_price_breaks}, without: {query_count_without_price_breaks})',
+        )
+
 
 class PartNotesTests(InvenTreeAPITestCase):
     """Tests for the 'notes' field (markdown field)."""

src/frontend/src/components/forms/ApiForm.tsx

@@ -174,8 +174,14 @@ export function ApiForm({
   );
 
   const defaultValues: FieldValues = useMemo(() => {
-    const defaultValuesMap = mapFields(fields ?? {}, (_path, field) => {
+    const defaultValuesMap = mapFields(props.fields ?? {}, (_path, field) => {
-      return field.value ?? field.default ?? undefined;
+      if (field.value !== undefined && field.value !== null) {
+        return field.value;
+      }
+      if (field.default !== undefined && field.default !== null) {
+        return field.default;
+      }
+      return undefined;
     });
 
     // If the user has specified initial data, that overrides default values
@@ -188,7 +194,6 @@ export function ApiForm({
         }
       });
     }
-
     return defaultValuesMap;
   }, [props.fields, props.initialData]);
 

src/frontend/src/components/forms/fields/ApiFormField.tsx

@@ -56,7 +56,11 @@ export function ApiFormField({
 
     // hook up the value state to the input field
     if (definition.value !== undefined) {
-      field.onChange(definition.value);
+      field.onChange(
+        definition.adjustValue
+          ? definition.adjustValue(definition.value)
+          : definition.value
+      );
     }
   }, [definition.value]);
 
@@ -112,7 +116,7 @@ export function ApiFormField({
 
     switch (definition.field_type) {
       case 'integer':
-        val = Number.parseInt(value) ?? '';
+        val = Number.parseInt(value, 10) ?? '';
         break;
       case 'decimal':
       case 'float':

src/frontend/src/forms/SalesOrderForms.tsx

@@ -101,14 +101,36 @@ export function useSalesOrderFields({
 export function useSalesOrderLineItemFields({
   customerId,
   orderId,
-  create
+  create,
+  currency
 }: {
   customerId?: number;
   orderId?: number;
   create?: boolean;
+  currency?: string;
 }): ApiFormFieldSet {
-  const fields = useMemo(() => {
+  const [salePrice, setSalePrice] = useState<string>('0');
-    return {
+  const [partCurrency, setPartCurrency] = useState<string>(currency ?? '');
+  const [part, setPart] = useState<any>({});
+  const [quantity, setQuantity] = useState<string>('');
+
+  useEffect(() => {
+    if (!create || !part || !part.price_breaks) return;
+
+    const qty = quantity ? Number.parseInt(quantity, 10) : 0;
+
+    const applicablePriceBreaks = part.price_breaks
+      .filter(
+        (pb: any) => pb.price_currency == partCurrency && qty <= pb.quantity
+      )
+      .sort((a: any, b: any) => a.quantity - b.quantity);
+
+    if (applicablePriceBreaks.length)
+      setSalePrice(applicablePriceBreaks[0].price);
+  }, [part, quantity, partCurrency, create]);
+
+  return useMemo(() => {
+    const fields: ApiFormFieldSet = {
       order: {
         filters: {
           customer_detail: true
@@ -119,20 +141,29 @@ export function useSalesOrderLineItemFields({
       part: {
         filters: {
           active: true,
-          salable: true
+          salable: true,
-        }
+          price_breaks: true
+        },
+        onValueChange: (_: any, record?: any) => setPart(record)
       },
       reference: {},
-      quantity: {},
+      quantity: {
-      sale_price: {},
+        onValueChange: setQuantity
-      sale_price_currency: {},
+      },
+      sale_price: {
+        value: salePrice
+      },
+      sale_price_currency: {
+        value: partCurrency,
+        onValueChange: setPartCurrency
+      },
       target_date: {},
       notes: {},
       link: {}
     };
-  }, []);
 
-  return fields;
+    return fields;
+  }, [salePrice, partCurrency, orderId, create]);
 }
 
 function SalesOrderAllocateLineRow({

src/frontend/src/tables/sales/SalesOrderLineItemTable.tsx

@@ -148,7 +148,7 @@ export default function SalesOrderLineItemTable({
             0
           );
 
-          let color: string | undefined = undefined;
+          let color: string | undefined;
           let text = `${formatDecimal(available)}`;
 
           const extra: ReactNode[] = [];
@@ -241,7 +241,8 @@ export default function SalesOrderLineItemTable({
   const createLineFields = useSalesOrderLineItemFields({
     orderId: orderId,
     customerId: customerId,
-    create: true
+    create: true,
+    currency: currency
   });
 
   const newLine = useCreateApiFormModal({