Order change: Allow to keep price when changing items

src/pretix/control/forms/orders.py

@@ -286,6 +286,7 @@ class OrderPositionChangeForm(forms.Form):
             ('secret', 'Regenerate secret'),
         )
     )
+    change_product_keep_price = forms.BooleanField(required=False)
 
     def __init__(self, *args, **kwargs):
         instance = kwargs.pop('instance')

src/pretix/control/templates/pretixcontrol/order/change.html

@@ -95,6 +95,10 @@
                                 {% trans "Change product to" %}
                                 {% bootstrap_field position.form.itemvar layout='inline' %}
                             </label>
+                            <label class="checkbox">
+                                {{ position.form.change_product_keep_price }}
+                                {% trans "Keep price the same" %}
+                            </label>
                         </div>
                         {% if request.event.has_subevents %}
                             <div class="radio">

src/pretix/control/views/orders.py

@@ -1229,7 +1229,7 @@ class OrderChange(OrderView):
                         variation = ItemVariation.objects.get(pk=varid, item=item)
                     else:
                         variation = None
-                    ocm.change_item(p, item, variation)
+                    ocm.change_item(p, item, variation, keep_price=p.form.cleaned_data['change_product_keep_price'])
                 elif p.form.cleaned_data['operation'] == 'price':
                     ocm.change_price(p, p.form.cleaned_data['price'])
                 elif p.form.cleaned_data['operation'] == 'subevent':