Allow ticket output methods to opt-out from ZIP generation

doc/development/api/ticketoutput.rst

@@ -58,6 +58,8 @@ The output class
 
    .. autoattribute:: is_enabled
 
+   .. autoattribute:: multi_download_enabled
+
    .. autoattribute:: settings_form_fields
 
    .. automethod:: settings_content_render

src/pretix/base/ticketoutput.py

@@ -32,6 +32,14 @@ class BaseTicketOutput:
         """
         return self.settings.get('_enabled', as_type=bool)
 
+    @property
+    def multi_download_enabled(self) -> bool:
+        """
+        Returns whether or not the ``generate_order`` method may be called. Returns
+        ``True`` by default.
+        """
+        return True
+
     def generate(self, position: OrderPosition) -> Tuple[str, str, str]:
         """
         This method should generate the download file and return a tuple consisting of a

src/pretix/presale/templates/pretixpresale/event/order.html

@@ -73,14 +73,16 @@
                     You can download your tickets using the buttons below. Please have your ticket ready when entering the event.
                 {% endblocktrans %}
             </div>
-            {% if cart.positions|length > 1 %}
+            {% if cart.positions|length > 1 and can_download_multi %}
                 <p>
                     {% trans "Download all tickets at once:" %}
                     {% for b in download_buttons %}
-                        <a href="{% eventurl event "presale:event.order.download.combined" secret=order.secret order=order.code output=b.identifier %}"
-                                class="btn btn-default btn-sm" data-asyncdownload>
-                            <span class="fa fa-download"></span> {{ b.text }}
-                        </a>
+                        {% if b.multi %}
+                            <a href="{% eventurl event "presale:event.order.download.combined" secret=order.secret order=order.code output=b.identifier %}"
+                                    class="btn btn-default btn-sm" data-asyncdownload>
+                                <span class="fa fa-download"></span> {{ b.text }}
+                            </a>
+                        {% endif %}
                     {% endfor %}
                 </p>
             {% endif %}

src/pretix/presale/views/order.py

@@ -76,6 +76,7 @@ class OrderDetails(EventViewMixin, OrderDetailMixin, CartMixin, TemplateView):
             buttons.append({
                 'text': provider.download_button_text or 'Download',
                 'identifier': provider.identifier,
+                'multi': provider.multi_download_enabled
             })
         return buttons
 
@@ -93,6 +94,7 @@ class OrderDetails(EventViewMixin, OrderDetailMixin, CartMixin, TemplateView):
             ) and self.order.status == Order.STATUS_PAID
         )
         ctx['download_buttons'] = self.download_buttons
+        ctx['can_download_multi'] = any([b['multi'] for b in self.download_buttons])
         ctx['cart'] = self.get_cart(
             answers=True, downloads=ctx['can_download'],
             queryset=self.order.positions.all(),