Reworked categories to enfore uniqueness at python-level.

To work around MySQL bug with fields of > 255 chars not being allowed to
have unique indexes.

oscar/apps/catalogue/abstract_models.py

@@ -56,7 +56,7 @@ class AbstractCategory(MP_Node):
     name = models.CharField(max_length=255, db_index=True)
     description = models.TextField(blank=True, null=True)
     image = models.ImageField(upload_to='categories', blank=True, null=True)
-    slug = models.SlugField(max_length=1024, db_index=True, editable=False, unique=True)
+    slug = models.SlugField(max_length=1024, db_index=True, editable=False)
     full_name = models.CharField(max_length=1024, db_index=True, editable=False)
 
     _slug_separator = '/'
@@ -76,6 +76,16 @@ def save(self, update_slugs=True, *args, **kwargs):
             else:
                 self.slug = slug
                 self.full_name = self.name
+
+        # Enforce slug uniqueness here as MySQL can't handle a unique index on
+        # the slug field
+        try:
+            match = self.__class__.objects.get(slug=self.slug)
+        except self.__class__.DoesNotExist:
+            pass
+        else:
+            if match.id != self.id:
+                raise ValidationError(_("A category with slug '%(slug)s' already exists") % {'slug': self.slug})
         super(AbstractCategory, self).save(*args, **kwargs)
 
     def move(self, target, pos=None):

oscar/templates/dashboard/catalogue/category_list.html

@@ -24,17 +24,15 @@ <h1>Category management</h1>
 
 {% block dashboard_content %}
 
-<div class="well well-info">
-	<p>You are editing:
-    <a href="{% url dashboard:catalogue-category-list %}">Home</a>
-    {% if ancestors %}
-	    &gt;
-        {% for ancestor in ancestors %}
-            <a href="{% url dashboard:catalogue-category-detail-list pk=ancestor.pk %}">{{ ancestor.name }}</a>{% if not forloop.last %} > {% endif %}
-        {% endfor %}
-    {% endif %}
-	</p>
-</div>
+<p>You are editing:
+<a href="{% url dashboard:catalogue-category-list %}">Home</a>
+{% if ancestors %}
+	&gt;
+	{% for ancestor in ancestors %}
+		<a href="{% url dashboard:catalogue-category-detail-list pk=ancestor.pk %}">{{ ancestor.name }}</a>{% if not forloop.last %} > {% endif %}
+	{% endfor %}
+{% endif %}
+</p>
 
 <table class="table table-striped table-bordered">
 	<thead>

tests/unit/catalogue_tests.py

@@ -124,6 +124,12 @@ def test_supports_has_children_method(self):
         root.add_child(name="Books")
         self.assertTrue(root.has_children())
 
+    def test_enforces_slug_uniqueness(self):
+        root = Category.add_root(name="Products")
+        root.add_child(name="Books")
+        with self.assertRaises(ValidationError):
+            root.add_child(name="Books")
+
 
 class ProductTests(TestCase):