Rails - Nov 2008 - Overwriting / Decorating ActiveRecord association accessor

Hi,
I am trying to overwrite the accessor of a has_many association.
Basically my class looks like this:

class Person
  has_many :emails
  has_one :link, :class_name => ''PersonProxy''

  def emails_with_link
     link.emails + emails_without_link
  end
  alias_method_chain :emails, :link
end

Now that works fine if I only access the collection like
>> Person.find(1).emails
=> [#<Email...]

But using any collection specific methods throw a
NoMethodError
>> Person.find(1).emails.build
=> NoMethodError: undefined method `build'' for
#<Array:0x226c634>

which makes sense, as I return an array...

But how do I return the Association? Or are there any other tricks to
implement this decorator for associations?

Cheers
Marcel

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On Nov 19, 6:08 pm, Marcel Hild
<h...-GOUVJj1Of1VeoWH0uzbU5w@public.gmane.org>
wrote:
> Hi,
> I am trying to overwrite the accessor of a has_many association.
> Basically my class looks like this:
>
> class Person
>   has_many :emails
>   has_one :link, :class_name => ''PersonProxy''
>
>   def emails_with_link
>      link.emails + emails_without_link
>   end
>   alias_method_chain :emails, :link
> end
>
> Now that works fine if I only access the collection like>>
Person.find(1).emails
>
> => [#<Email...]
>
> But using any collection specific methods throw a NoMethodError>>
Person.find(1).emails.build
>
> => NoMethodError: undefined method `build'' for
#<Array:0x226c634>
>
> which makes sense, as I return an array...
>
The trick is that link.emails isn''t an array - it''s an
association
proxy.
I''m not sure what the write thing to do here is. Maybe something like

has_many :emails do
  def load_target
    super
    proxy_target += proxy_owner.link.emails
  end
end

might do the trick ?

Fred
> But how do I return the Association? Or are there any other tricks to
> implement this decorator for associations?
>
> Cheers
> Marcel
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>
> The trick is that link.emails isn''t an array - it''s an
association
> proxy.
> I''m not sure what the write thing to do here is. Maybe something
like
>
Thanks so much for your input. You got me in the right direction:

has_many :emails do
    def load_target
      super
      if !loaded? and proxy_owner.link.respond_to?(:emails)
        @target += proxy_owner.link.emails
      end
      @target
    end
  end

This works like a charm :) Thumbs up!

Marcel
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I was a bit too fast and euphoric :)
Now this works better:

  has_many :emails do
    def load_target
      super
      if not @loaded_link and proxy_owner.link.respond_to?(:emails)
        puts "loading link"
        @target += proxy_owner.link.emails
        @loaded_link = true
      end
      @target
    end
    def reset
      super
      @loaded_link = false
    end
  end


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