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    <p>I don't think that you can load users and profiles with join in Rails. I think that in earlier versions of Rails ( &lt; 2.1) loading of associated models was done with joins, but it was not efficient. <a href="https://stackoverflow.com/questions/1208636/rails-include-vs-joins">Here</a> you have some explanation and links to other materials.</p> <p>So even if you explicite say that you want to join it, Rails won't map it to associated models. So if you say <code>Profile.whatever_here</code> it will always be mapped to <code>Profile</code> object.</p> <p>If you still want to do what you said in question, then you can call custom sql query and process results by yourself:</p> <pre><code>p = ActiveRecord::Base.connection.execute("SELECT * FROM profiles JOIN users ON profiles.user_id = users.id LIMIT 1") </code></pre> <p>and get results row by row with:</p> <pre><code>p.fetch_row </code></pre> <p>It will already be mappet to an array.</p> <p>Your errors are because you are calling <code>first_name</code> and <code>user</code> method on <code>AciveRecord::Relation</code> object and it stores an array of <code>Profile</code> objects, not a single object. So</p> <pre><code>p = Profile.joins(:user).limit(1) p[0].first_name </code></pre> <p>shoud work.</p> <p>Better way to fetch only one record is to call:</p> <pre><code>p = Profile.joins(:user).first p.first_name p.user </code></pre> <p>But when you call <code>p.user</code> it will query database. To avoid it, you can use <code>include</code>, but if you load only one profile object, it is useless. It will make a difference if you load many profiles at a time and want to inlcude users table.</p>
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