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POChange a finder method w/ parameters to an association
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  1. POChange a finder method w/ parameters to an association
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    copied!<p>How do I turn this into a has_one association? </p> <p>(Possibly has_one + a named scope for size.)</p> <pre><code>class User &lt; ActiveRecord::Base has_many :assets, :foreign_key =&gt; 'creator_id' def avatar_asset size = :thumb # The LIKE is because it might be a .jpg, .png, or .gif. # More efficient methods that can handle that are OK. ;) self.assets.find :first, :conditions =&gt; ["thumbnail = '#{size}' and filename LIKE ?", self.login + "_#{size}.%"] end end </code></pre> <p>EDIT: Cuing from AnalogHole on Freenode #rubyonrails, we can do this:</p> <pre><code> has_many :assets, :foreign_key =&gt; 'creator_id' do def avatar size = :thumb find :first, :conditions =&gt; ["thumbnail = ? and filename LIKE ?", size.to_s, proxy_owner.login + "_#{size}.%"] end end </code></pre> <p>... which is fairly cool, and makes syntax a bit better at least.</p> <p>However, this still doesn't behave as well as I would like. Particularly, it doesn't allow for further nice find chaining (such that it doesn't execute this find until it's gotten all its conditions).</p> <p>More importantly, it doesn't allow for use in an :include. Ideally I want to do something like this:</p> <pre><code>PostsController def show post = Post.get_cache(params[:id]) { Post.find(params[:id], :include =&gt; {:comments =&gt; {:users =&gt; {:avatar_asset =&gt; :thumb}} } ... end </code></pre> <p>... so that I can cache the assets together with the post. Or cache them at all, really - e.g. <code>get_cache(user_id){User.find(user_id, :include =&gt; :avatar_assets)}</code> would be a good first pass.</p> <p>This doesn't actually work (self == User), but is correct in spirit:</p> <pre><code>has_many :avatar_assets, :foreign_key =&gt; 'creator_id', :class_name =&gt; 'Asset', :conditions =&gt; ["filename LIKE ?", self.login + "_%"] </code></pre> <p>(Also posted on <a href="http://refactormycode.com/codes/900-change-a-finder-method-w-parameters-to-an-association" rel="nofollow noreferrer">Refactor My Code</a>.)</p>
 

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