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---
layout: post
title: Same class associations in Rails 3
tags:
- Development
status: publish
type: post
published: true
meta:
_edit_last: '1'
_cws_is_markdown: '1'
---
<strong>[TL;DR]</strong> Even though the selected events conceptually belong to a record, the latter has the foreign keys to former. So technically, <code>has_one</code> is to be changed to <code>belongs_to</code>.
<hr />
This is the first time I've ran into something like this and it was interesting to realize what it actually means when developing a business logic in Rails.
<h3>Context</h3>
In this app I'm building, I have <em>Students</em> that have a <em>Record</em> per year. Each record has several <em>Events</em>. These records also have two specific events: a <em>test</em> and an <em>audition</em>, registered in the schema as <code>id</code>'s in the record's table.
<h3>So what did technically happen?</h3>
I wasn't able to access those specific events through the associations specified in the model. Given <code>r = Record.first</code>, when I tried to access the audition, by using <code>r.test</code>, Rails would use a SQL query that would correspond to <code>r.events.first</code> instead.
After acknowledging that, I turned to <a href="http://twitter.com/varandas">@varandas</a> and we both thought it might be a bug in the Rails framework. Turns out it wasn't; all I had to do was switch from <code>has_one</code> to <code>belongs_to</code> (thanks <a href="http://github.com/drogus">@drogus</a>!). The reason for that is the foreign key is on the <code>records</code> table. From the framework's perspective, it looks like the record actually <em>belongs to</em> the event, when in practice it's not.
<h3>Code sample</h3>
[gist id=1449428]
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