Widget: remove limit of 50 events in list-view by adding a load-more-button (#2144)

src/pretix/base/models/event.py

@@ -1004,6 +1004,11 @@ class Event(EventMixin, LoggedModel):
                 | Q(date_to__gte=now() - timedelta(hours=24))
             )
         )  # order_by doesn't make sense with I18nField
+        if ordering in ("date_ascending", "date_descending"):
+            # if primary order is by date, then order in database
+            # this allows to limit/slice results
+            return subevs.order_by(*orderfields)
+
         for f in reversed(orderfields):
             if f.startswith('-'):
                 subevs = sorted(subevs, key=attrgetter(f[1:]), reverse=True)

src/pretix/presale/views/widget.py

@@ -422,7 +422,10 @@ class WidgetAPIProductList(EventListMixin, View):
         data['list_type'] = list_type
 
         if hasattr(self.request, 'event') and data['list_type'] not in ("calendar", "week"):
-            if self.request.event.subevents.filter(date_from__gt=now()).count() > 50:
+            # only allow list-view of more than 50 subevents if ordering is by data as this can be done in the database
+            # ordering by name is currently not supported in database due to I18NField-JSON
+            ordering = self.request.event.settings.get('frontpage_subevent_ordering', default='date_ascending', as_type=str)
+            if ordering not in ("date_ascending", "date_descending") and self.request.event.subevents.filter(date_from__gt=now()).count() > 50:
                 if self.request.event.settings.event_list_type not in ("calendar", "week"):
                     self.request.event.settings.event_list_type = "calendar"
                 data['list_type'] = list_type = 'calendar'
@@ -537,10 +540,21 @@ class WidgetAPIProductList(EventListMixin, View):
             for d in data['days']:
                 d['events'] = self._serialize_events(d['events'] or [])
         else:
+            offset = int(self.request.GET.get("offset", 0))
+            limit = 50
             if hasattr(self.request, 'event'):
                 evs = self.request.event.subevents_sorted(
                     filter_qs_by_attr(self.request.event.subevents_annotated(self.request.sales_channel.identifier), self.request)
                 )
+                ordering = self.request.event.settings.get('frontpage_subevent_ordering', default='date_ascending', as_type=str)
+                data['has_more_events'] = False
+                if ordering in ("date_ascending", "date_descending"):
+                    # fetch one more result than needed to check if more events exist
+                    evs = list(evs[offset:offset + limit + 1])
+                    if len(evs) > limit:
+                        data['has_more_events'] = True
+                        evs = evs[:limit]
+
                 tz = pytz.timezone(request.event.settings.timezone)
                 if self.request.event.settings.event_list_available_only:
                     evs = [

src/pretix/static/pretixpresale/js/widget/widget.js

@@ -53,6 +53,7 @@ var strings = {
     'next_week': django.pgettext('widget', 'Next week'),
     'previous_week': django.pgettext('widget', 'Previous week'),
     'show_seating': django.pgettext('widget', 'Open seat selection'),
+    'load_more': django.pgettext('widget', 'Load more'),
     'days': {
         'MO': django.gettext('Mo'),
         'TU': django.gettext('Tu'),
@@ -854,6 +855,8 @@ Vue.component('pretix-widget-event-form', {
             this.$root.target_url = this.$root.parent_stack.pop();
             this.$root.error = null;
             this.$root.subevent = null;
+            this.$root.offset = 0;
+            this.$root.append_events = false;
             this.$root.trigger_load_callback();
             if (this.$root.events !== undefined && this.$root.events !== null) {
                 this.$root.view = "events";
@@ -938,9 +941,12 @@ Vue.component('pretix-widget-event-list', {
         + '</div>'
         + '<div class="pretix-widget-event-description" v-if="$root.parent_stack.length > 0 && $root.frontpage_text" v-html="$root.frontpage_text"></div>'
         + '<pretix-widget-event-list-entry v-for="event in $root.events" :event="event" :key="event.url"></pretix-widget-event-list-entry>'
+        + '<p class="pretix-widget-event-list-load-more" v-if="$root.has_more_events"><button @click.prevent="load_more">'+strings.load_more+'</button></p>'
         + '</div>'),
     methods: {
         back_to_calendar: function () {
+            this.$root.offset = 0;
+            this.$root.append_events = false;
             if (this.$root.weeks) {
                 this.$root.events = undefined;
                 this.$root.view = "weeks";
@@ -953,6 +959,12 @@ Vue.component('pretix-widget-event-list', {
                 this.$root.reload();
             }
         },
+        load_more: function () {
+            this.$root.append_events = true;
+            this.$root.offset += 50;
+            this.$root.loading++;
+            this.$root.reload();
+        }
     }
 });
 
@@ -1353,6 +1365,9 @@ var shared_root_methods = {
         } else {
             url = this.$root.target_url + 'widget/product_list?lang=' + lang;
         }
+        if (this.$root.offset) {
+            url += '&offset=' + this.$root.offset;
+        }
         if (this.$root.filter) {
             url += '&' + this.$root.filter;
         }
@@ -1408,11 +1423,13 @@ var shared_root_methods = {
                 root.name = data.name;
                 root.frontpage_text = data.frontpage_text;
             } else if (data.events !== undefined) {
-                root.events = data.events;
+                root.events = root.append_events && root.events ? root.events.concat(data.events) : data.events;
+                root.append_events = false;
                 root.weeks = undefined;
                 root.view = "events";
                 root.name = data.name;
                 root.frontpage_text = data.frontpage_text;
+                root.has_more_events = data.has_more_events;
             } else {
                 root.view = "event";
                 root.name = data.name;
@@ -1647,6 +1664,9 @@ var create_widget = function (element) {
                 currency: null,
                 name: null,
                 date_range: null,
+                offset: 0,
+                has_more_events: false,
+                append_events: false,
                 frontpage_text: null,
                 filter: filter,
                 item_filter: items,

src/pretix/static/pretixpresale/scss/widget.scss

@@ -172,6 +172,15 @@
 
   .pretix-widget-loading svg {
     margin: 40px;
+    /*Fallback*/
+    position: absolute;
+    top: 50%;
+    margin-top: -64px;
+    /*Sticky*/
+    position: -webkit-sticky;
+    position: sticky;
+    top: Min(50vh, 50%);/* use uppercase M to use CSS-min and not SASS-min*/
+
     -webkit-animation: pretix-widget-spin 6s linear infinite;
     -moz-animation: pretix-widget-spin 6s linear infinite;
     animation: pretix-widget-spin 6s linear infinite;
@@ -699,6 +708,10 @@
   fill: $brand-primary;
 }
 
+.pretix-widget-event-list-load-more {
+  text-align: center;
+}
+
 .pretix-widget.pretix-widget-mobile {
   .pretix-widget-event-week-table {
     display: block;

src/tests/presale/test_widget.py

@@ -520,6 +520,7 @@ class WidgetCartTest(CartTestMixin, TestCase):
                 'name': '30C3',
                 'frontpage_text': '',
                 'poweredby': '<a href="https://pretix.eu" target="_blank" rel="noopener">ticketing powered by pretix</a>',
+                'has_more_events': False,
                 'events': [
                     {'name': 'Present', 'date_range': 'Jan. 1, 2019 11:00', 'availability': {'color': 'none', 'text': '', 'reason': 'unknown'},
                      'event_url': 'http://example.com/ccc/30c3/', 'subevent': se1.pk, 'location': ''},