truncate error description in admin

Also removes old conditional imports

django_q/admin.py

@@ -34,8 +34,7 @@ class TaskAdmin(admin.ModelAdmin):
 
     def get_readonly_fields(self, request, obj=None):
         """Set all fields readonly."""
-        return list(self.readonly_fields) + \
+        return list(self.readonly_fields) + [field.name for field in obj._meta.fields]
-               [field.name for field in obj._meta.fields]
 
 
 def retry_failed(FailAdmin, request, queryset):
@@ -56,7 +55,7 @@ class FailAdmin(admin.ModelAdmin):
         'func',
         'started',
         'stopped',
-        'result'
+        'short_result'
     )
 
     def has_add_permission(self, request):
@@ -70,8 +69,7 @@ class FailAdmin(admin.ModelAdmin):
 
     def get_readonly_fields(self, request, obj=None):
         """Set all fields readonly."""
-        return list(self.readonly_fields) + \
+        return list(self.readonly_fields) + [field.name for field in obj._meta.fields]
-               [field.name for field in obj._meta.fields]
 
 
 class ScheduleAdmin(admin.ModelAdmin):

django_q/models.py

@@ -1,8 +1,7 @@
 from django import get_version
-try:
+from django.template.defaultfilters import truncatechars
-    from django.urls import reverse
+
-except ImportError: # Django < 1.10
+from django.urls import reverse
-    from django.core.urlresolvers import reverse
 from django.utils.html import format_html
 from django.utils.translation import ugettext_lazy as _
 from django.db import models
@@ -82,6 +81,10 @@ class Task(models.Model):
     def time_taken(self):
         return (self.stopped - self.started).total_seconds()
 
+    @property
+    def short_result(self):
+        return truncatechars(self.result, 100)
+
     def __unicode__(self):
         return u'{}'.format(self.name or self.id)
 

django_q/tests/test_admin.py

@@ -1,7 +1,4 @@
-try:
+from django.urls import reverse
-    from django.urls import reverse
-except ImportError: # Django < 1.10
-    from django.core.urlresolvers import reverse
 from django.utils import timezone
 
 import pytest