[feature] Line discount (#12393)

* Add "discount" support to order line items

* Fix total_price annotation for ExtraLineItem

* Add regression tests

* Add frontend support

* Updated documentation

* Added docs

* Bump API version and CHANGELOG

* Remove 'total_price' annotation

- Can be achieved using in-memory python methods

* Apply fix for migration testing

* Revert "Apply fix for migration testing"

This reverts commit 8d9f2dce8c.

* Different approach

* Adjust playwright threshold

src/frontend/src/components/tables/ColumnRenderers.tsx

@@ -473,6 +473,22 @@ export function DecimalColumn(props: TableColumn): TableColumn {
   };
 }
 
+export function PercentageColumn(props: TableColumn): TableColumn {
+  return {
+    sortable: true,
+    render: (record: any) => {
+      const value = resolveItem(record, props.accessor ?? '');
+
+      if (value == null || value === 0) {
+        return '-';
+      }
+
+      return `${formatDecimal(value)}%`;
+    },
+    ...props
+  };
+}
+
 export function DescriptionColumn(props: TableColumnProps): TableColumn {
   return {
     accessor: 'description',

src/frontend/src/forms/CommonForms.tsx

@@ -91,6 +91,7 @@ export function extraLineItemFields(): ApiFormFieldSet {
     quantity: {},
     price: {},
     price_currency: {},
+    discount: {},
     project_code: ProjectCodeField(),
     notes: {},
     link: {}

src/frontend/src/forms/PurchaseOrderForms.tsx

@@ -186,6 +186,7 @@ export function usePurchaseOrderLineItemFields({
         value: purchasePriceCurrency,
         onValueChange: setPurchasePriceCurrency
       },
+      discount: {},
       auto_pricing: {
         default: create !== false,
         value: autoPricing,

src/frontend/src/forms/ReturnOrderForms.tsx

@@ -133,6 +133,7 @@ export function useReturnOrderLineItemFields({
       },
       price: {},
       price_currency: {},
+      discount: {},
       project_code: ProjectCodeField(),
       target_date: {},
       notes: {},

src/frontend/src/forms/SalesOrderForms.tsx

@@ -197,6 +197,7 @@ export function useSalesOrderLineItemFields({
         value: partCurrency,
         onValueChange: setPartCurrency
       },
+      discount: {},
       project_code: ProjectCodeField(),
       target_date: {},
       notes: {},

src/frontend/src/tables/general/ExtraLineItemTable.tsx

@@ -19,6 +19,7 @@ import {
   LineItemColumn,
   LinkColumn,
   NoteColumn,
+  PercentageColumn,
   ProjectCodeColumn
 } from '../../components/tables/ColumnRenderers';
 import { InvenTreeTable } from '../../components/tables/InvenTreeTable';
@@ -69,13 +70,17 @@ export default function ExtraLineItemTable({
             currency: record.price_currency
           })
       },
+      PercentageColumn({
+        accessor: 'discount',
+        title: t`Discount`,
+        defaultVisible: false
+      }),
       {
         accessor: 'total_price',
         title: t`Total Price`,
         render: (record: any) =>
-          formatCurrency(record.price, {
-            currency: record.price_currency,
-            multiplier: record.quantity
+          formatCurrency(record.total_price, {
+            currency: record.price_currency
           })
       },
       ProjectCodeColumn({}),

src/frontend/src/tables/purchasing/PurchaseOrderLineItemTable.tsx

@@ -30,6 +30,7 @@ import {
   LocationColumn,
   NoteColumn,
   PartColumn,
+  PercentageColumn,
   ProjectCodeColumn,
   ReferenceColumn,
   TargetDateColumn
@@ -254,13 +255,17 @@ export function PurchaseOrderLineItemTable({
         accessor: 'purchase_price',
         title: t`Unit Price`
       }),
+      PercentageColumn({
+        accessor: 'discount',
+        title: t`Discount`,
+        defaultVisible: false
+      }),
       {
         accessor: 'total_price',
         title: t`Total Price`,
         render: (record: any) =>
-          formatCurrency(record.purchase_price, {
-            currency: record.purchase_price_currency,
-            multiplier: record.quantity
+          formatCurrency(record.total_price, {
+            currency: record.purchase_price_currency
           })
       },
       TargetDateColumn({}),

src/frontend/src/tables/sales/ReturnOrderLineItemTable.tsx

@@ -23,6 +23,7 @@ import {
   LinkColumn,
   NoteColumn,
   PartColumn,
+  PercentageColumn,
   ProjectCodeColumn,
   ReferenceColumn,
   StatusColumn,
@@ -148,6 +149,11 @@ export default function ReturnOrderLineItemTable({
         render: (record: any) =>
           formatCurrency(record.price, { currency: record.price_currency })
       },
+      PercentageColumn({
+        accessor: 'discount',
+        title: t`Discount`,
+        defaultVisible: false
+      }),
       DateColumn({
         accessor: 'target_date',
         title: t`Target Date`

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

@@ -36,6 +36,7 @@ import {
   IPNColumn,
   LineItemColumn,
   LinkColumn,
+  PercentageColumn,
   ProjectCodeColumn,
   ReferenceColumn,
   RenderPartColumn,
@@ -121,13 +122,18 @@ export default function SalesOrderLineItemTable({
             currency: record.sale_price_currency
           })
       },
+      PercentageColumn({
+        accessor: 'discount',
+        title: t`Discount`,
+        defaultVisible: false
+      }),
       {
         accessor: 'total_price',
         title: t`Total Price`,
         render: (record: any) =>
           formatCurrency(record.sale_price, {
             currency: record.sale_price_currency,
-            multiplier: record.quantity
+            multiplier: record.quantity * (1 - (record.discount ?? 0) / 100)
           })
       },
       DateColumn({

src/frontend/tests/pui_login.spec.ts

@@ -157,7 +157,7 @@ test('Login - Cold vs Warm vs Hot Load', async ({ page }) => {
   // Note: Vite server in dev mode is significantly slower than production build
   const COLD_MS_THRESHOLD: number = 5000;
   const WARM_MS_THRESHOLD: number = 4000;
-  const HOT_MS_THRESHOLD: number = 3000;
+  const HOT_MS_THRESHOLD: number = 3500;
 
   const coldMs = await loginAndMeasure(page);