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PO
 

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    <p>I never tried to do this but you may want to try the following (I just changed how the aliases are done):</p> <pre><code>class Property &lt; ActiveRecord::Base has_and_belongs_to_many :property_values, :extend =&gt; PropertyUtil::Extensible def enrich(to_extend) modules.split(/\s*,\s*/).each do |mod| to_extend.extend(Properties.const_get(mod.to_sym)) end end end module PropertyUtil module Extensible def self.extended(mod) mod.module_eval do alias_method :old_find, :find alias_method :find, :new_find end end def new_find(*args) old_find(*args).map{|prop| proxy_owner.enrich(prop)} end end end </code></pre> <p>If it does not work here is another idea you may wanna try:</p> <pre><code>class Value &lt; ActiveRecord::Base self.abstract_class = true end class ExtendedValue &lt; Value end class ExtendedValue2 &lt; Value end class Property &lt; ActiveRecord::Base has_and_belongs_to_many :property_values, :class_name =&gt; 'ExtendedValue' has_and_belongs_to_many :property_values_extended, :class_name =&gt; 'ExtendedValue' has_and_belongs_to_many :property_values_extended2, :class_name =&gt; 'ExtendedValue2' end </code></pre> <p>The idea is to have one hatbm association per "type" (if you can group your extensions that way) and use the one you want at a given time, if you can do what you want that way I am also pretty sure it will have a smaller impact performance than patching every returned object after activerecord returned them.</p> <p>I am kinda curious at what you are trying to achieve with this :)</p>
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    1. POHow can I extend an object returned from an ActiveRecord association at runtime?
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    1. USSchmurfy
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    1. COThanks for your response! The goal is to provide a more flexible sort of single-table inheritance, where a number of different modules can compose to provide behavior and data semantics for property values without having to modify the database to accommodate new types. In my implementation, there is a single text property, value_str, which stores a JSON document; the various modules, when composed, define both the structure of the document and how to process its data. Users can mix and match the available modules in any desired combination.
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    2. CODid you have a look to composed_of ? It may also be a part of a solution to your problem.
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    3. COcomposed_of is close, but it's part of the class definition and doesn't look like it gives you the opportunity to resolve the module names after the record has been retrieved from the database.
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