Device list: Show online status (#6455)

* Device list: Show online status

* Fixes post-review

src/pretix/base/models/devices.py

@@ -20,11 +20,13 @@
 # <https://www.gnu.org/licenses/>.
 #
 import string
+from datetime import timedelta
 
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.db.models import Max
 from django.utils.crypto import get_random_string
+from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _
 from django_scopes import ScopedManager, scopes_disabled
 
@@ -307,3 +309,8 @@ class DeviceLastSeen(models.Model):
                 autosummarize=True
             )
         ]
+
+    @property
+    def is_recent(self):
+        # pretixSCAN/pretixPOS sync every 5 minutes, so 7 minutes can be considered "offline"
+        return now() - self.last_seen < timedelta(minutes=7)

src/pretix/control/templates/pretixcontrol/organizers/devices.html

@@ -118,6 +118,10 @@
                                 </td>
                             {% endif %}
                             <td>
+                                <span class="fa fa-fw {% if d.last_seen and d.last_seen.is_recent %}fa-check-circle text-success{% else %}fa-circle text-danger{% endif %}"
+                                      data-toggle="tooltip"
+                                      title="{% if d.last_seen %}{% blocktrans with time=d.last_seen.last_seen|date:"SHORT_DATETIME_FORMAT" %}Last seen: {{ time }}{% endblocktrans %}{% else %}{% trans "No recent contact" %}{% endif %}"
+                                ></span>
                                 {{ d.device_id }}
                             </td>
                             <td>
@@ -125,6 +129,7 @@
                                     <del>{% endif %}
                                 {{ d.name }}
                                 {% if d.revoked %}</del>{% endif %}
+
                                 {% if d.gate %}
                                     <br>
                                     <small class="text-muted">{{ d.gate.name }}</small>

src/pretix/control/views/organizer.py

@@ -108,7 +108,9 @@ from pretix.base.services.export import (
     init_organizer_exporters, multiexport, scheduled_organizer_export,
 )
 from pretix.base.services.mail import mail, prefix_subject
-from pretix.base.services.placeholders import prepare_sample_context_for_preview
+from pretix.base.services.placeholders import (
+    prepare_sample_context_for_preview,
+)
 from pretix.base.templatetags.rich_text import markdown_compile_email
 from pretix.base.views.tasks import AsyncAction
 from pretix.control.forms.exports import ScheduledOrganizerExportForm
@@ -1206,7 +1208,7 @@ class DeviceQueryMixin:
     def get_queryset(self):
         qs = self.request.organizer.devices.prefetch_related(
             'limit_events', 'gate',
-        ).order_by('revoked', '-device_id')
+        ).select_related('last_seen').order_by('revoked', '-device_id')
 
         if 'device' in self.request_data and '__ALL' not in self.request_data:
             qs = qs.filter(