---
id: task-4
title: Set up ActiveRecord associations
status: Done
assignee: []
created_date: '2025-07-13'
updated_date: '2025-07-13'
labels: []
dependencies: []
---

## Description

Create the has_one association between STI class and auxiliary table

## Acceptance Criteria

- [x] has_one association is created automatically
- [x] Foreign key is properly configured
- [x] Association name is consistent and predictable

## Implementation Plan

1. Analyze existing implementation in generate_aux_model_class method
2. Verify has_one association is properly configured with correct foreign key
3. Ensure association name follows consistent naming convention
4. Update task documentation to mark completion

## Implementation Notes

The has_one association was already implemented in the generate_aux_model_class method in task-3. The implementation correctly:

- Creates has_one association automatically when aux_table is defined
- Uses proper foreign key configuration based on base STI class (e.g., vehicle_id for Vehicle STI)
- Follows consistent naming convention using table_name.to_s.singularize.to_sym
- Supports lazy loading as standard ActiveRecord has_one associations do

The association is set up in lines 158-162 of lib/has_aux_table.rb:
```ruby
T.unsafe(self).has_one(
  table_name.to_s.singularize.to_sym,
  class_name: class_name,
  foreign_key: "#{base_class_name}_id"
)
```

All tests pass and the implementation meets all acceptance criteria.
