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POAvoiding STI in Rails
 

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    <pre><code>class User &lt; ActiveRecord::Base has_one :location, :dependent =&gt; :destroy, :as =&gt; :locatable has_one :ideal_location, :dependent =&gt; :destroy, :as =&gt; :locatable has_one :birthplace, :dependent =&gt; :destroy, :as =&gt; :locatable end class Location &lt; ActiveRecord::Base belongs_to :locatable, :polymorphic =&gt; true end class IdealLocation &lt; ActiveRecord::Base end class Birthplace &lt; ActiveRecord::Base end </code></pre> <p>I can't really see any reason to have subclasses in this situation. The behavior of the location objects are identical, the only point of them is to make the associations easy. I also would prefer to store the data as an int and not a string as it will allow the database indexes to be smaller.</p> <p>I envision something like the following, but I can't complete the thought:</p> <pre><code>class User &lt; ActiveRecord::Base LOCATION_TYPES = { :location =&gt; 1, :ideal_location =&gt; 2, :birthplace =&gt; 3 } has_one :location, :conditions =&gt; ["type = ?", LOCATION_TYPES[:location]], :dependent =&gt; :destroy, :as =&gt; :locatable has_one :ideal_location, :conditions =&gt; ["type = ?", LOCATION_TYPES[:ideal_location]], :dependent =&gt; :destroy, :as =&gt; :locatable has_one :birthplace, :conditions =&gt; ["type = ?", LOCATION_TYPES[:birthplace]], :dependent =&gt; :destroy, :as =&gt; :locatable end class Location &lt; ActiveRecord::Base belongs_to :locatable, :polymorphic =&gt; true end </code></pre> <p>With this code the following fails, basically making it useless:</p> <pre><code>user = User.first location = user.build_location location.city = "Cincinnati" location.state = "Ohio" location.save! location.type # =&gt; nil </code></pre> <p>This is obvious because there is no way to translate the :conditions options on the has_one declaration into the type equaling 1.</p> <p>I could embed the id in the view anywhere these fields appear, but this seems wrong too:</p> <pre><code>&lt;%= f.hidden_field :type, LOCATION_TYPES[:location] %&gt; </code></pre> <p>Is there any way to avoid the extra subclasses or make the LOCATION_TYPES approach work?</p> <p>In our particular case the application is very location aware and objects can have many different types of locations. Am I just being weird not wanting all those subclasses?</p> <p>Any suggestions you have are appreciated, tell me I'm crazy if you want, but would you want to see 10+ different location models floating around app/models?</p>
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