Increase max_length on NewsItem.slug. Autogenerate a slug containing the date and slugified title, taking in account of duplicates.

news/migrations/0004_auto_20160610_1743.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.6 on 2016-06-10 17:43
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('news', '0003_newsitem_slug'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='newsitem',
+            name='slug',
+            field=models.SlugField(max_length=255),
+        ),
+    ]

news/models.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 from django.db import models
+from django.utils.text import slugify
 
 from utils.models import CreatedUpdatedModel
 from news.managers import NewsItemQuerySet
@@ -14,9 +15,34 @@ class NewsItem(CreatedUpdatedModel):
     content = models.TextField()
     public = models.BooleanField(default=False)
     published_at = models.DateTimeField()
-    slug = models.SlugField()
+    slug = models.SlugField(max_length=255, blank=True)
 
     def __str__(self):
         return self.title
 
+    def save(self, **kwargs):
+        if (
+            not self.pk or
+            not self.slug or
+            NewsItem.objects.filter(slug=self.slug).count() > 1
+        ):
+            published_at_string = self.published_at.strftime('%Y-%m-%d')
+            base_slug = slugify(self.title)
+            slug = '{}-{}'.format(published_at_string, base_slug)
+            incrementer = 1
+
+            # We have to make sure that the slug won't clash with current slugs
+            while NewsItem.objects.filter(slug=slug).exists():
+                if incrementer == 1:
+                    slug = '{}-1'.format(slug)
+                else:
+                    slug = '{}-{}'.format(
+                        '-'.join(slug.split('-')[:-1]),
+                        incrementer
+                    )
+                incrementer += 1
+            self.slug = slug
+
+        super(NewsItem, self).save(**kwargs)
+
     objects = NewsItemQuerySet.as_manager()