added custom template filter for slots

gracedb/api.py

@@ -917,7 +917,7 @@ class EventSlot(APIView):
             # when encoded in the HTTP request body.  Hence the 'None' string 
             # below.  If somebody intentionally named a file 'None', then 
             # they deserve to get this error message.
-            if filename=='' or filename=='None' or filename=None:
+            if filename=='' or filename=='None' or filename==None:
                 return Response("Please submit a filename or upload a file.",
                         status=status.HTTP_400_BAD_REQUEST)
             # Check for existence of the file.

gracedb/templatetags/slot.py

+
+from django import template
+from django.utils.encoding import force_unicode
+from django.utils.safestring import mark_safe
+from ..models import Slot, EventLog
+register = template.Library()
+
+@register.filter("slot")
+def slot(event,slotname):
+    if event is None:
+        return mark_safe("")
+    try:
+        slot = Slot.objects.filter(event=event).filter(name=slotname)[0]
+        out = slot.value
+    except:
+        return mark_safe("Object not found.")
+    return mark_safe(out)
+