API: Allow to add a fee to an order (#4806)

doc/api/resources/orders.rst

@@ -2242,6 +2242,9 @@ otherwise, such as splitting an order or changing fees.
    * ``patch_fees``: A list of objects with the two keys ``fee`` specifying an order fee ID and
      ``body`` specifying the desired changed values of the position (``value``).
 
+   * ``create_fees``: A list of objects describing new order fees with the fields ``fee_type``, ``value``, ``description``,
+     ``internal_type``, ``tax_rule``
+
    * ``cancel_fees``: A list of objects with the single key ``fee`` specifying an order fee ID.
 
    * ``recalculate_taxes``: If set to ``"keep_net"``, all taxes will be recalculated based on the tax rule and invoice

src/pretix/api/serializers/orderchange.py

@@ -30,7 +30,7 @@ from rest_framework.exceptions import ValidationError
 
 from pretix.api.serializers.order import (
     AnswerCreateSerializer, AnswerSerializer, CompatibleCountryField,
-    OrderPositionCreateSerializer,
+    OrderFeeCreateSerializer, OrderPositionCreateSerializer,
 )
 from pretix.base.models import ItemVariation, Order, OrderFee, OrderPosition
 from pretix.base.services.orders import OrderError
@@ -104,6 +104,54 @@ class OrderPositionCreateForExistingOrderSerializer(OrderPositionCreateSerialize
             raise ValidationError(str(e))
 
 
+class OrderFeeCreateForExistingOrderSerializer(OrderFeeCreateSerializer):
+    order = serializers.SlugRelatedField(slug_field='code', queryset=Order.objects.none(), required=True, allow_null=False)
+    value = serializers.DecimalField(required=True, allow_null=False, decimal_places=2,
+                                     max_digits=13)
+    internal_type = serializers.CharField(required=False, default="")
+
+    class Meta:
+        model = OrderFee
+        fields = ('order', 'fee_type', 'value', 'description', 'internal_type', 'tax_rule')
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        if not self.context:
+            return
+        self.fields['order'].queryset = self.context['event'].orders.all()
+        self.fields['tax_rule'].queryset = self.context['event'].tax_rules.all()
+        if 'order' in self.context:
+            del self.fields['order']
+
+    def validate(self, data):
+        data = super().validate(data)
+        if 'order' in self.context:
+            data['order'] = self.context['order']
+        return data
+
+    def create(self, validated_data):
+        ocm = self.context['ocm']
+
+        try:
+            f = OrderFee(
+                order=validated_data['order'],
+                fee_type=validated_data['fee_type'],
+                value=validated_data.get('value'),
+                description=validated_data.get('description'),
+                internal_type=validated_data.get('internal_type'),
+                tax_rule=validated_data.get('tax_rule'),
+            )
+            f._calculate_tax()
+            ocm.add_fee(f)
+            if self.context.get('commit', True):
+                ocm.commit()
+                return validated_data['order'].fees.order_by('-pk').first()
+            else:
+                return OrderFee()  # fake to appease DRF
+        except OrderError as e:
+            raise ValidationError(str(e))
+
+
 class OrderPositionInfoPatchSerializer(serializers.ModelSerializer):
     answers = AnswerSerializer(many=True)
     country = CompatibleCountryField(source='*')
@@ -401,6 +449,9 @@ class OrderChangeOperationSerializer(serializers.Serializer):
         self.fields['split_positions'] = SelectPositionSerializer(
             many=True, required=False, context=self.context
         )
+        self.fields['create_fees'] = OrderFeeCreateForExistingOrderSerializer(
+            many=True, required=False, context=self.context
+        )
         self.fields['patch_fees'] = PatchFeeSerializer(
             many=True, required=False, context=self.context
         )

src/pretix/api/views/order.py

@@ -63,7 +63,8 @@ from pretix.api.serializers.order import (
 )
 from pretix.api.serializers.orderchange import (
     BlockNameSerializer, OrderChangeOperationSerializer,
-    OrderFeeChangeSerializer, OrderPositionChangeSerializer,
+    OrderFeeChangeSerializer, OrderFeeCreateForExistingOrderSerializer,
+    OrderPositionChangeSerializer,
     OrderPositionCreateForExistingOrderSerializer,
     OrderPositionInfoPatchSerializer,
 )
@@ -988,6 +989,12 @@ class EventOrderViewSet(OrderViewSetMixin, viewsets.ModelViewSet):
                 ocm.cancel_fee(r['fee'])
                 canceled_fees.add(r['fee'])
 
+            for r in serializer.validated_data.get('create_fees', []):
+                pos_serializer = OrderFeeCreateForExistingOrderSerializer(
+                    context={'ocm': ocm, 'commit': False, 'event': request.event, **self.get_serializer_context()},
+                )
+                pos_serializer.create(r)
+
             for r in serializer.validated_data.get('patch_fees', []):
                 if r['fee'] in canceled_fees:
                     continue

src/tests/api/test_order_change.py

@@ -1797,6 +1797,13 @@ def test_order_change_cancel_and_create(token_client, organizer, event, order, q
                 'price': '99.99'
             },
         ],
+        'create_fees': [
+            {
+                'value': '5.99',
+                'fee_type': 'service',
+                'description': 'Service fee',
+            },
+        ],
         'cancel_fees': [
             {
                 'fee': f.pk,
@@ -1818,6 +1825,11 @@ def test_order_change_cancel_and_create(token_client, organizer, event, order, q
         assert p_new.price == Decimal('99.99')
         f.refresh_from_db()
         assert f.canceled
+        f_new = order.all_fees.get(fee_type=OrderFee.FEE_TYPE_SERVICE)
+        assert f_new.value == Decimal('5.99')
+        assert f_new.description == "Service fee"
+        assert f_new.internal_type == ""
+        assert f_new.tax_value == Decimal('0.00')
 
 
 @pytest.mark.django_db