Adds extra line item model for the return order

- Adds serializer and API endpoints as appropriate

InvenTree/order/api.py

@@ -1319,6 +1319,25 @@ class ReturnOrderDetail(RetrieveUpdateDestroyAPI):
         return self.serializer_class(*args, **kwargs)
 
 
+class ReturnOrderExtraLineList(GeneralExtraLineList, ListCreateAPI):
+    """API endpoint for accessing a list of ReturnOrderExtraLine objects"""
+
+    queryset = models.ReturnOrderExtraLine.objects.all()
+    serializer_class = serializers.ReturnOrderExtraLineSerializer
+
+    def download_queryset(self, queryset, export_format):
+        """Download this queryset as a file"""
+
+        raise NotImplementedError("download_queryset not yet implemented")
+
+
+class ReturnOrderExtraLineDetail(RetrieveUpdateDestroyAPI):
+    """API endpoint for detail view of a ReturnOrderExtraLine object"""
+
+    queryset = models.ReturnOrderExtraLine.objects.all()
+    serializer_class = serializers.ReturnOrderExtraLineSerializer
+
+
 class ReturnOrderAttachmentList(AttachmentMixin, ListCreateDestroyAPIView):
     """API endpoint for listing (and creating) a ReturnOrderAttachment (file upload)"""
 
@@ -1581,6 +1600,12 @@ order_api_urls = [
     # API endpoints for return orders
     re_path(r'^return/', include([
 
+        # API endpoints for return order extra line
+        re_path(r'^extra-line/', include([
+            path('<int:pk>/', ReturnOrderExtraLineDetail.as_view(), name='api-return-order-extra-line-detail'),
+            path('', ReturnOrderExtraLineList.as_view(), name='api-return-order-extra-line-list'),
+        ])),
+
         re_path(r'^attachment/', include([
             path('<int:pk>/', ReturnOrderAttachmentDetail.as_view(), name='api-return-order-attachment-detail'),
             re_path(r'^.*$', ReturnOrderAttachmentList.as_view(), name='api-return-order-attachment-list'),

InvenTree/order/migrations/0082_returnorderextraline.py

@@ -0,0 +1,35 @@
+# Generated by Django 3.2.18 on 2023-03-16 02:52
+
+import InvenTree.fields
+import django.core.validators
+from django.db import migrations, models
+import django.db.models.deletion
+import djmoney.models.fields
+import djmoney.models.validators
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('order', '0081_auto_20230314_1259'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ReturnOrderExtraLine',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('quantity', InvenTree.fields.RoundingDecimalField(decimal_places=5, default=1, help_text='Item quantity', max_digits=15, validators=[django.core.validators.MinValueValidator(0)], verbose_name='Quantity')),
+                ('reference', models.CharField(blank=True, help_text='Line item reference', max_length=100, verbose_name='Reference')),
+                ('notes', models.CharField(blank=True, help_text='Line item notes', max_length=500, verbose_name='Notes')),
+                ('target_date', models.DateField(blank=True, help_text='Target date for this line item (leave blank to use the target date from the order)', null=True, verbose_name='Target Date')),
+                ('context', models.JSONField(blank=True, help_text='Additional context for this line', null=True, verbose_name='Context')),
+                ('price_currency', djmoney.models.fields.CurrencyField(choices=[], default='', editable=False, max_length=3)),
+                ('price', InvenTree.fields.InvenTreeModelMoneyField(blank=True, currency_choices=[], decimal_places=6, default_currency='', help_text='Unit price', max_digits=19, null=True, validators=[djmoney.models.validators.MinMoneyValidator(0)], verbose_name='Price')),
+                ('order', models.ForeignKey(help_text='Return Order', on_delete=django.db.models.deletion.CASCADE, related_name='extra_lines', to='order.returnorder', verbose_name='Order')),
+            ],
+            options={
+                'abstract': False,
+            },
+        ),
+    ]

InvenTree/order/models.py

@@ -1682,6 +1682,21 @@ class ReturnOrder(Order):
     )
 
 
+class ReturnOrderExtraLine(OrderExtraLine):
+    """Model for a single ExtraLine in a ReturnOrder"""
+
+    @staticmethod
+    def get_api_url():
+        """Return the API URL associated with the ReturnOrderExtraLine model"""
+        return reverse('api-return-order-extra-line-list')
+
+    order = models.ForeignKey(
+        ReturnOrder, on_delete=models.CASCADE,
+        related_name='extra_lines',
+        verbose_name=_('Order'), help_text=_('Return Order')
+    )
+
+
 class ReturnOrderAttachment(InvenTreeAttachment):
     """Model for storing file attachments against a ReturnOrder object"""
 

InvenTree/order/serializers.py

@@ -1441,6 +1441,16 @@ class ReturnOrderSerializer(AbstractOrderSerializer, InvenTreeModelSerializer):
     customer_detail = CompanyBriefSerializer(source='customer', many=False, read_only=True)
 
 
+class ReturnOrderExtraLineSerializer(AbstractExtraLineSerializer, InvenTreeModelSerializer):
+    """Serializer for a ReturnOrderExtraLine object"""
+
+    class Meta(AbstractExtraLineMeta):
+        """Metaclass options"""
+        model = order.models.ReturnOrderExtraLine
+
+    order_detail = ReturnOrderSerializer(source='order', many=False, read_only=True)
+
+
 class ReturnOrderAttachmentSerializer(InvenTreeAttachmentSerializer):
     """Serializer for the ReturnOrderAttachment model"""