# Critical Database Field Fixes Required

## Summary
Found 62 field name inconsistencies across 6 Python files that need to be fixed to match the database schema.

## Most Critical Issues

### 1. **Sessions Table Field References**
The sessions table has duplicate columns that are causing confusion:

| Database Column | Code References (Wrong) | Files Affected |
|----------------|------------------------|----------------|
| `hardware_id` | `device_id` | api_routes.py, session_routes.py, export_routes.py |
| `is_active` | `active` | api_routes.py, session_routes.py, export_routes.py, batch_routes.py |
| `started_at` | `login_time` | session_routes.py, export_routes.py |
| `last_heartbeat` | `last_activity` | session_routes.py, export_routes.py |
| `ended_at` | `logout_time` | api_routes.py, session_routes.py, export_routes.py |
| `started_at` | `start_time` | models.py |

### 2. **Device Registration Issues**
- `device_registrations` table uses `device_id` column (line 324 in api_routes.py)
- But sessions table uses `hardware_id`
- This creates a mismatch when joining tables

## Immediate Action Required

### Option 1: Fix Code (Recommended)
Update all Python files to use the correct column names from the database schema.

### Option 2: Add Compatibility Columns (Temporary)
```sql
-- Add missing columns to sessions for backward compatibility
ALTER TABLE sessions ADD COLUMN IF NOT EXISTS device_id VARCHAR(100);
UPDATE sessions SET device_id = hardware_id WHERE device_id IS NULL;

-- Update device_registrations to use hardware_id
ALTER TABLE device_registrations RENAME COLUMN device_id TO hardware_id;
```

## Files That Need Updates

1. **routes/session_routes.py** (15 occurrences)
   - Lines: 84, 134, 325 (device_id)
   - Lines: 85, 109, 112, 119, 124, 135, 150 (login_time)
   - Lines: 86, 119, 136, 202, 248 (logout_time)
   - Lines: 87, 137 (last_activity)
   - Lines: 88, 124, 138, 192, 202, 236, 248, 249, 328, 340, 361 (active)

2. **routes/api_routes.py** (12 occurrences)
   - Lines: 203, 214, 345, 861 (device_id)
   - Lines: 204, 344, 345, 453, 455, 457, 862 (active)
   - Line: 344 (logout_time)

3. **routes/export_routes.py** (11 occurrences)
   - Lines: 47, 72, 224, 244 (device_id)
   - Lines: 46, 71, 228, 233, 248 (active)
   - Lines: 225, 234, 245, 253, 254 (login_time)
   - Lines: 226, 246 (logout_time)
   - Lines: 227, 247 (last_activity)

4. **models.py** (2 occurrences)
   - Line: 167 (start_time)
   - Line: 177 (active - but this is just in error message)

5. **routes/batch_routes.py** (2 occurrences)
   - Lines: 212, 213 (active)

6. **routes/customer_routes.py** (1 occurrence)
   - Line: 392 (comment mentions correction already made)

## Testing After Fixes

1. Test all session-related functionality
2. Verify device registration/deregistration works
3. Check session history displays correctly
4. Ensure exports contain correct data
5. Validate batch operations still function