Order API: Add `exclude` query parameter

doc/api/resources/orders.rst

@@ -159,6 +159,10 @@ last_modified                         datetime                   Last modificati
 
    The ``search`` query parameter has been added.
 
+.. versionchanged:: 3.11
+
+   The ``exclude`` query parameter has been added.
+
 
 .. _order-position-resource:
 
@@ -485,6 +489,7 @@ List of all orders
        recommend using this in combination with ``testmode=false``, since test mode orders can vanish at any time and
        you will not notice it using this method.
    :query datetime created_since: Only return orders that have been created since the given date.
+   :query string exclude: Exclude a field from the output, e.g. ``fees`` or ``positions.downloads``. Can be used as a performance optimization. Can be passed multiple times.
    :param organizer: The ``slug`` field of the organizer to fetch
    :param event: The ``slug`` field of the event to fetch
    :resheader X-Page-Generated: The server time at the beginning of the operation. If you're using this API to fetch

src/pretix/api/serializers/order.py

@@ -376,6 +376,14 @@ class OrderSerializer(I18nAwareModelSerializer):
         if not self.context['request'].query_params.get('pdf_data', 'false') == 'true':
             self.fields['positions'].child.fields.pop('pdf_data')
 
+        for exclude_field in self.context['request'].query_params.getlist('exclude'):
+            p = exclude_field.split('.')
+            if p[0] in self.fields:
+                if len(p) == 1:
+                    del self.fields[p[0]]
+                elif len(p) == 2:
+                    self.fields[p[0]].child.fields.pop(p[1])
+
     def validate_locale(self, l):
         if l not in set(k for k in self.instance.event.settings.locales):
             raise ValidationError('"{}" is not a supported locale for this event.'.format(l))

src/pretix/api/views/order.py

@@ -121,16 +121,19 @@ class OrderViewSet(viewsets.ModelViewSet):
         return ctx
 
     def get_queryset(self):
-        if self.request.query_params.get('include_canceled_fees', 'false') == 'true':
-            fqs = OrderFee.all
-        else:
-            fqs = OrderFee.objects
-        qs = self.request.event.orders.prefetch_related(
-            Prefetch('fees', queryset=fqs.all()),
-            'payments', 'refunds', 'refunds__payment'
-        ).select_related(
-            'invoice_address'
-        )
+        qs = self.request.event.orders
+        if 'fees' not in self.request.GET.getlist('exclude'):
+            if self.request.query_params.get('include_canceled_fees', 'false') == 'true':
+                fqs = OrderFee.all
+            else:
+                fqs = OrderFee.objects
+            qs = qs.prefetch_related(Prefetch('fees', queryset=fqs.all()))
+        if 'payments' not in self.request.GET.getlist('exclude'):
+            qs = qs.prefetch_related('payments')
+        if 'refunds' not in self.request.GET.getlist('exclude'):
+            qs = qs.prefetch_related('refunds', 'refunds__payment')
+        if 'invoice_address' not in self.request.GET.getlist('exclude'):
+            qs = qs.select_related('invoice_address')
 
         if self.request.query_params.get('include_canceled_positions', 'false') == 'true':
             opq = OrderPosition.all