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PORails Polymorphic has_many
 

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    <p>Using Ruby on Rails, how can I achieve a polymorphic <code>has_many</code> relationship where the owner is always of a known but the items in the association will be of some polymorphic (but homogenous) type, specified by a column in the owner? For example, suppose the <code>Producer</code> class <code>has_many</code> products but producer instances might actually have many Bicycles, or Popsicles, or Shoelaces. I can easily have each product class (Bicycle, Popsicle, etc.) have a <code>belongs_to</code> relationship to a Producer but given a producer instance how can I get the collection of products if they are of varying types (per producer instance)?</p> <p>Rails polymorphic associations allow producers to belong to many products, but I need the relationship to be the other way around. For example:</p> <pre><code>class Bicycle &lt; ActiveRecord::Base belongs_to :producer end class Popsicle &lt; ActiveRecord::Base belongs_to :producer end class Producer &lt; ActiveRecord::Base has_many :products, :polymorphic_column =&gt; :type # last part is made-up... end </code></pre> <p>So my Producer table already has a "type" column which corresponds to some product class (e.g. Bicycle, Popsicle, etc.) but how can I get Rails to let me do something like:</p> <pre><code>&gt;&gt; bike_producer.products #=&gt; [Bicycle@123, Bicycle@456, ...] &gt;&gt; popsicle_producer.products #=&gt; [Popsicle@321, Popsicle@654, ...] </code></pre> <p>Sorry if this is obvious or a common repeat; I'm having surprising difficulty achieving it easily.</p>
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    1. COJust as a note, I strongly recommend against using Factory as a model name, as factory_girl is a very commonly used extension used for generating models instead of fixtures, and this may be very confusing for people reading your code.
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    2. CO@jamie - thanks for the tip, I've switch terminology to "Producer", which hopefully won't be confused with any concurrency libraries =)
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    3. CONo problem. Also, I haven't found a good solution to this. As far as I know, the ability for an object to have polymorphic children does not yet exist in Rails. You may want to check out http://blog.hasmanythrough.com/2006/4/3/polymorphic-through for reference though.
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