Fixed server-side sorting for user-related columns on dashboard:
Problem:
- Clicking "Created By" or "Assigned To" headers didn't sort
- Columns were missing from $allowedColumns validation
- Fell back to ticket_id sort, appearing random to users
Solution:
1. Added 'created_by' and 'assigned_to' to $allowedColumns array
2. Smart sort expression mapping:
- created_by → sorts by display_name/username (not user ID)
- assigned_to → uses CASE to put unassigned at end, then sorts by name
- Other columns → use table prefix (t.column_name)
3. Database-level NULL handling for assigned_to:
- Uses CASE WHEN to sort unassigned tickets last
- Regardless of ASC/DESC direction
- Then alphabetically sorts assigned users
Result:
- A→Z: Alice, Bob, Charlie... Unassigned
- Z→A: Zack, Yolanda, Xavier... Unassigned
- Consistent grouping and predictable order
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>