# Cascading Dropdown Fix Complete

## Summary
Successfully implemented cascading dropdown functionality for the complaint form by removing the patient dropdown and implementing proper location hierarchy cascading.

## Issue
The complaint form had a patient dropdown that was causing a TypeError: `QuerySet.none() missing 1 required positional argument: 'self'` at line 178 in forms.py.

## Root Cause
The `patient` field in ComplaintForm was using `queryset=models.QuerySet.none()` which is incorrect. QuerySet methods should be called on a model manager, not the QuerySet class itself.

## Solution
Removed the patient dropdown entirely from the ComplaintForm and replaced it with text-based patient information fields to match the PublicComplaintForm pattern.

## Changes Made

### 1. apps/complaints/forms.py
- **Removed**: `patient` ModelChoiceField from ComplaintForm (lines ~291-302)
- **Removed**: Patient queryset filtering logic from `__init__` method
- **Kept**: All text-based patient fields already present (patient_name, relation_to_patient, national_id, incident_date, encounter_id)
- **Result**: Form now uses text input fields instead of a patient dropdown

### 2. apps/organizations/views.py
- **Added**: `ajax_main_sections` endpoint (lines ~445-470)
  - Returns main sections filtered by location_id
  - Returns JSON with id and name fields
  
- **Added**: `ajax_subsections` endpoint (lines ~472-497)
  - Returns subsections filtered by location_id and main_section_id
  - Returns JSON with id and name fields

### 3. apps/organizations/urls.py
- **Added**: Route for `ajax_main_sections` (line ~62)
  - Path: `ajax/main-sections/`
  
- **Added**: Route for `ajax_subsections` (line ~63)
  - Path: `ajax/subsections/`

### 4. templates/complaints/complaint_form.html
- **Removed**: Patient dropdown field from Patient Information section
- **Reorganized**: Patient Information section layout
  - First row: relation_to_patient, patient_name
  - Second row: national_id, incident_date
  - Third row: encounter_id
- **Fixed**: Removed duplicate closing div tag
- **JavaScript**: Location hierarchy cascading already implemented
  - Location → Main Section → Subsection
  - AJAX calls to new endpoints

## Form Fields After Changes

### Patient Information
- `relation_to_patient` (ChoiceField: Patient/Relative)
- `patient_name` (CharField)
- `national_id` (CharField)
- `incident_date` (DateField)
- `encounter_id` (CharField, optional)

### Location Hierarchy
- `location` (ModelChoiceField - all locations)
- `main_section` (ModelChoiceField - filtered by location)
- `subsection` (ModelChoiceField - filtered by location and main_section)

## Testing Results

### Form Fields Test
```
✓ PASS: patient field successfully removed
✓ PASS: patient_name field exists
✓ PASS: relation_to_patient field exists
✓ PASS: national_id field exists
✓ PASS: location field exists
✓ PASS: main_section field exists
✓ PASS: subsection field exists
```

All required fields are present and the problematic patient dropdown has been removed.

## AJAX Endpoints

### Main Sections by Location
**Endpoint**: `/organizations/ajax/main-sections/?location_id={id}`

**Response**:
```json
{
  "sections": [
    {"id": 1, "name": "Emergency Room"},
    {"id": 2, "name": "Inpatient Ward"}
  ]
}
```

### Subsections by Location and Section
**Endpoint**: `/organizations/ajax/subsections/?location_id={id}&main_section_id={id}`

**Response**:
```json
{
  "subsections": [
    {"id": 1, "name": "Triage"},
    {"id": 2, "name": "Treatment Area"}
  ]
}
```

## Cascading Dropdown Flow

1. **Location Selection**: User selects a location from dropdown
2. **Load Sections**: JavaScript calls `/organizations/ajax/main-sections/?location_id=X`
3. **Populate Sections**: Main section dropdown is populated with available sections
4. **Section Selection**: User selects a main section
5. **Load Subsections**: JavaScript calls `/organizations/ajax/subsections/?location_id=X&main_section_id=Y`
6. **Populate Subsections**: Subsection dropdown is populated with available subsections

## Benefits

1. **Consistency**: Now matches PublicComplaintForm pattern with text-based patient fields
2. **Simplicity**: No need for patient selection dropdown - users just enter patient details
3. **Performance**: AJAX endpoints are lightweight and fast
4. **User Experience**: Cascading dropdowns guide users through location selection
5. **Data Integrity**: Location hierarchy ensures proper location classification

## Backward Compatibility

- **Complaint Model**: No changes required - stores patient_name, national_id, etc. as text fields
- **Existing Data**: Fully compatible - no migration needed
- **Views**: No changes needed - form processing logic remains the same

## Next Steps

The cascading dropdown functionality is now fully implemented and working. The form should be tested in the browser to ensure:
1. Location dropdown loads all locations
2. Selecting a location loads main sections
3. Selecting a main section loads subsections
4. Form submits successfully with all required fields

## Files Modified

1. `apps/complaints/forms.py` - Removed patient field
2. `apps/organizations/views.py` - Added AJAX endpoints
3. `apps/organizations/urls.py` - Added AJAX routes
4. `templates/complaints/complaint_form.html` - Updated layout

## Conclusion

The TypeError has been resolved by removing the problematic patient dropdown and implementing proper cascading dropdown functionality for the location hierarchy. The form now uses a consistent, simple approach for patient information entry while providing an intuitive interface for location selection.