added filter to get seconds from datetime

smash/web/templatetags/filters.py

@@ -2,6 +2,7 @@
 from django import template
 from django.forms import CheckboxSelectMultiple, CheckboxInput
 from django.utils.safestring import mark_safe
+import datetime
 
 register = template.Library()
 
@@ -40,3 +41,8 @@ def render_appointments(statistics, appointment_type):
     for status_count in statistics.get(appointment_type, []):
         html += '<td>{}</td>'.format(status_count)
     return mark_safe(html)
+
+@register.filter(name="timestamp")
+def timestamp(value):
+    epoch = datetime.datetime.utcfromtimestamp(0)
+    return (value.replace(tzinfo=None) - epoch).total_seconds()