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POHow to create a conditional based on the existence of an attribute in Rails?
 

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  1. POHow to create a conditional based on the existence of an attribute in Rails?
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    <p>I have the following code in a likes_controller and it works fine as long as a <code>thing</code> has an <code>owner</code>. If not, it breaks. </p> <pre><code> def create @thing = Thing.find(params[:like][:liked_id]) user = @thing.owner current_user.like!(@thing) current_user.follow!(user) respond_with @thing end </code></pre> <p>I've tried using </p> <pre><code>user = @thing.owner if @thing.owner.exists? </code></pre> <p>but I get a NoMethodError:</p> <pre><code>NoMethodError in LikesController#create undefined method `exists?' for nil:NilClass </code></pre> <p>How do I check for the existence of an <code>owner</code>?</p> <p>I also now notice I'll have to put the second line (<code>current_user.follow!(user)</code>) in the block or it will break again...</p> <p>Edit: This worked (using @Amadan's answer):</p> <pre><code>def create @thing = Thing.find(params[:like][:liked_id]) current_user.like!(@thing) user = @thing.owner if user current_user.follow!(user) end respond_with @thing end </code></pre> <p>Additional information: In case anyone ever actually uses this, I should point out that one more small change is necessary to get this to work. The above code errors out if a <code>user</code> tried to <code>like</code> a <code>thing</code> when they are already <code>following</code> the <code>thing</code>'s <code>owner</code>. </p> <p>so instead of </p> <pre><code>if user </code></pre> <p>I used</p> <pre><code>if user &amp;&amp; !current_user.following?(user) </code></pre> <p>Hope this is helpful.</p>
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