fix: update model and migration

server/apps/research/migrations/0016_category_slug.py

@@ -4,10 +4,17 @@
 
 def remove_duplicate_slugs(apps, schema_editor):
     Category = apps.get_model('research', 'Category')
-    duplicate_slugs = Category.objects.values('slug').annotate(count=models.Count('slug')).filter(count__gt=1)
-    for slug in duplicate_slugs:
-        Category.objects.filter(slug=slug['slug']).exclude(id=models.Min('id')).delete()
-
+    seen_slugs = {}
+
+    for category in Category.objects.order_by('id'):
+        base_slug = category.slug
+        counter = 1
+        while category.slug in seen_slugs:
+            category.slug = f"{base_slug}-{counter}"
+            counter += 1
+        seen_slugs[category.slug] = True
+        category.save()
+
 class Migration(migrations.Migration):
 
     dependencies = [

server/apps/research/models/category.py

@@ -12,8 +12,13 @@ class Meta:
         verbose_name_plural = 'Categories'
 
     def save(self, *args, **kwargs):
-        if not self.slug:
-            self.slug = self.generate_slug()        
+        try:
+            if not self.slug:
+                self.slug = self.generate_slug()
+            if len(self.slug) > 255:
+                raise ValueError("Generated slug exceeds maximum length")
+        except ValueError as e:
+            raise ValueError(f"Failed to generate valid slug: {str(e)}")     
         super().save(*args, **kwargs)
 
     def __str__(self):