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    <p>Let's start with some style and design issues and end with the actual answer:</p> <ol> <li><p>Models are singular by convention. Doing otherwise will only cause you more work. In this case, I would suggest <code>Following</code> as a suitable name, as in "a user has many followings".</p></li> <li><p>Foreign keys should end with <code>_id</code>. Doing otherwise will only cause you more work. So <code>follower_id</code> and <code>followed_id</code>.</p></li> <li><p>Methods that are intended to be used for their true/false nature ("<a href="http://reinh.com/blog/2008/07/16/ruby-patterns-query-method.html">query methods</a>") should end with a ?, so <code>follows?</code> instead of <code>follows</code>,</p></li> <li><p>Your if statement is redundant and can be safely removed once the condition does the right thing. In ruby, in the context of conditionals, we care more about whether things <em>evaluate</em> to true/false than whether they are literally <code>true</code> or <code>false</code>. This means that anything other than <code>nil</code> or <code>false</code> will be "truthy".</p></li> <li><p>The fact that your method depends entirely on information known to <code>User</code> objects indicates that it would be better to hang it off of those objects, for instance <code>current_user.follows? other_user</code>.</p></li> <li><p>You are duplicating behavior that would already be provided to you by using associations.</p></li> </ol> <p>Finally, taking all of these things into consideration, the answer:</p> <pre><code>class User &lt; ActiveRecord::Base has_many :followings, :class_name =&gt; 'Following', :foreign_key =&gt; 'followed_id' has_many :followers, :through =&gt; 'followings' def follows?(other) other.followed_by? self end def followed_by?(other) followers.include? other end end </code></pre> <p><strong>NB</strong>: The use of the <code>followed_by?</code> method here is a use of <a href="http://en.wikipedia.org/wiki/Double_dispatch">double dispatch</a> that prevents the (minor) <a href="http://c2.com/cgi/wiki?LawOfDemeter">Law of Demeter violation</a> of one user knowing directly about the state of another user's followers. Rather, the first user object asks the second user object a direct question ("Are you followed by me?") and bases the result off of the answer. (It is also likely to be a useful method in and of itself.)</p>
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    1. USRein Henrichs
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    1. COThanks so much for showing me the proper, corrent way to do this, rather than just a quick fix!
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      1. USMark Provan
    2. COWhat a thoughtful and complete answer. Wish I had more than one upvote.
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      1. USRob Di Marco
 

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