Use proper timezone when rendering tentative schedule slots

In particular, when publishing a schedule we'd use the server default
timezone when showing the difference (reported in #180) and also when adding
new sessions.

Fixes #180

Author: mhagander

postgresqleu/confreg/models.py

@@ -23,7 +23,7 @@
 from postgresqleu.util.validators import color_validator
 from postgresqleu.util.forms import ChoiceArrayField
 from postgresqleu.util.fields import LowercaseEmailField, ImageBinaryField, PdfBinaryField
-from postgresqleu.util.time import today_conference
+from postgresqleu.util.time import today_conference, datetime_string
 from postgresqleu.util.db import exec_no_result
 from postgresqleu.util.image import rescale_image_bytes
 from postgresqleu.util.currency import format_currency
@@ -1130,7 +1130,7 @@ class ConferenceSessionScheduleSlot(models.Model):
     endtime = models.DateTimeField(null=False, blank=False, verbose_name="End time")
 
     def __str__(self):
-        return "%s - %s" % (self.starttime, self.endtime)
+        return "%s - %s" % (datetime_string(self.starttime), datetime_string(self.endtime))
 
 
 class ConferenceSessionTag(models.Model):

postgresqleu/confreg/views.py

@@ -79,6 +79,7 @@
 from postgresqleu.util.db import exec_no_result, exec_to_list, exec_to_scalar, conditional_exec_to_scalar
 from postgresqleu.util.db import ensure_conference_timezone
 from postgresqleu.util.qr import generate_base64_qr
+from postgresqleu.util.time import datetime_string
 from postgresqleu.scheduler.util import trigger_immediate_job_run
 
 from decimal import Decimal
@@ -3232,7 +3233,7 @@ def publishschedule(request, confname):
             if s.starttime:
                 # Has an existing time, did it change?
                 if s.starttime != s.tentativescheduleslot.starttime or s.endtime != s.tentativescheduleslot.endtime:
-                    changes.append("Session '%s': moved from '%s' to '%s'" % (s.title, s.starttime, s.tentativescheduleslot.starttime))
+                    changes.append("Session '%s': moved from '%s' to '%s'" % (s.title, datetime_string(s.starttime), datetime_string(s.tentativescheduleslot.starttime)))
                     s.starttime = s.tentativescheduleslot.starttime
                     s.endtime = s.tentativescheduleslot.endtime
                     dirty = True