Use more sensible defaults for check-in lists in event series (#3147)

src/pretix/control/templates/pretixcontrol/subevents/bulk.html

@@ -515,6 +515,16 @@
         </fieldset>
         <fieldset>
             <legend>{% trans "Check-in lists" %}</legend>
+            <p class="help-block">
+                {% blocktrans trimmed %}
+                    You can choose to either add one or more check-in lists for every date in your series individually,
+                    or use just one check-in list for all your dates and limit admission through check-in rules. Which
+                    approach is better depends on multiple factors, such as the number of dates in your series. For a
+                    series with one or less event date per day, individual lists are usually more helpful. If you
+                    use dates to represent many time slots on the same day, or even overlapping time slots, working with
+                    just one large check-in list will be easier.
+                {% endblocktrans %}
+            </p>
             <div class="formset" data-formset data-formset-prefix="{{ cl_formset.prefix }}">
                 {{ cl_formset.management_form }}
                 {% bootstrap_formset_errors cl_formset %}

src/pretix/control/templates/pretixcontrol/subevents/detail.html

@@ -157,6 +157,16 @@
                 </fieldset>
                 <fieldset>
                     <legend>{% trans "Check-in lists" %}</legend>
+                    <p class="help-block">
+                        {% blocktrans trimmed %}
+                            You can choose to either add one or more check-in lists for every date in your series individually,
+                            or use just one check-in list for all your dates and limit admission through check-in rules. Which
+                            approach is better depends on multiple factors, such as the number of dates in your series. For a
+                            series with one or less event date per day, individual lists are usually more helpful. If you
+                            use dates to represent many time slots on the same day, or even overlapping time slots, working with
+                            just one large check-in list will be easier.
+                        {% endblocktrans %}
+                    </p>
                     <div class="formset" data-formset data-formset-prefix="{{ cl_formset.prefix }}">
                         {{ cl_formset.management_form }}
                         {% bootstrap_formset_errors cl_formset %}

src/pretix/control/views/main.py

@@ -306,10 +306,11 @@ class EventWizard(SafeSessionWizardView):
                 event.set_active_plugins(settings.PRETIX_PLUGINS_DEFAULT.split(","),
                                          allow_restricted=settings.PRETIX_PLUGINS_DEFAULT.split(","))
                 event.save(update_fields=['plugins'])
-                event.checkin_lists.create(
-                    name=_('Default'),
-                    all_products=True
-                )
+                if not event.has_subevents:
+                    event.checkin_lists.create(
+                        name=_('Default'),
+                        all_products=True
+                    )
                 event.set_defaults()
 
             if basics_data['tax_rate']:

src/pretix/control/views/subevents.py

@@ -251,7 +251,9 @@ class SubEventEditorMixin(MetaDataEditorMixin):
                     'include_pending': False,
                 }
             ]
-            extra = 0
+
+            if not self.request.event.checkin_lists.filter(subevent__isnull=True).exists():
+                extra = 1
 
         formsetclass = inlineformset_factory(
             SubEvent, CheckinList,