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POIs it possible to assign multiple has_many ":as" polymorphic relation on same field?
 

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  1. POIs it possible to assign multiple has_many ":as" polymorphic relation on same field?
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    <p>Having my db setup like this ("type" is always User although I have different kind of User via STI):</p> <pre><code>class User # fields # :id # :sender_id, :sender_type # :recipient_id, :recipient_type end </code></pre> <p>Postcard model:</p> <pre><code>class Postcard &lt; ActiveRecord::Base belongs_to :owner, :class_name =&gt; User belongs_to :recipient, :class_name =&gt; User end </code></pre> <p>I'd like to setup the User model something like this:</p> <pre><code>class User &lt; ActiveRecord::Base has_many :postcards, :as =&gt; [:sender or :recipient] # this is not working end </code></pre> <p>So I could say:</p> <pre><code>user.postcards </code></pre> <p>Is it possible?</p> <p>PS: I've also tried this road:</p> <pre><code> has_many :postcards, :finder_sql =&gt; Proc.new { "SELECT * FROM postcards WHERE postcards.owner_id=#{id} OR postcards.recipient_id=#{id}" } </code></pre> <p>But found myself stuck on scopes as :finder_sql recreates a whole new SQL:</p> <pre><code> User.postcards.by_status('new').size </code></pre>
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    1. USAdit Saxena
    1. USAdit Saxena
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    1. CORails polymorphic associations typically are different than you're writing. To do your Sender or Receiver, you would typically create a class that works for both such as: class Postcard < ActiveRecord::Base belongs_to :mailable, :polymorphic => true end class Sender < ActiveRecord::Base has_many :postcards, :as => :mailable end class Receiver < ActiveRecord::Base has_many :postcards, :as => :mailable end
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      1. USjoelparkerhenderson
    2. CO@joelparkerhenderson thanks for your reply. Unfortunately I have multiple User types for example: Doctor < User and Patient < User. Being each User either a Sender or a Receiver I think final code would be unreadable/unusable. Am I right?
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      1. POIs it possible to assign multiple has_many ":as" polymorphic relation on same field?
      1. USAdit Saxena
    3. CODepends on how you set it up. In general Rails STI (Single Table Inheritance) works pretty well for classes with large overlap IMHO; a more advanced way to set up your classes is by changing from inheritance to associations (so a Doctor has_one User) or to DCI (Data Context Integration) which makes Doctor and Patient two "roles" that a user can mix in at runtime. There's also a way to do double-sided polymorphic joins-- try searching for an older gem by Evan Weaver that does it, and see if it's maintained or has a successor.
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      1. POIs it possible to assign multiple has_many ":as" polymorphic relation on same field?
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