add get_absolute_url method to newsletter objects

newsletter/models.py

@@ -12,6 +12,7 @@ from email.mime.text import MIMEText
 import html2text
 
 from django.db import models
+from django.core.urlresolvers import reverse
 
 from django.template import loader, Context 
 from django.conf import settings
@@ -96,3 +97,6 @@ class Newsletter(models.Model):
 
         self.expedition_datetime = datetime.datetime.now()
         self.save()
+
+    def get_absolute_url(self):
+        return reverse('newsletter-view', kwargs={'pk': self.id})