Rails - Jun 2006 - instantiate record in single table inheritance

Hi,

is there a way to instantiate a _concrete_ subtype from within an 
ActiveRecord collection?

Example:

class Link < ActiveRecord::Base
end

class InternalLink < Link
end

class ExternalLink < Link
end

internal_link = my_navigation.links.create_[xxxxxxx]
external_link = my_navigation.links.create_[xxxxxxxx]

the [xxx] is what I am missing...

I could do this
 
 external_link = my_navigation.links.create(:type => ExternalLink.to_s)

but in this case the validations of ExternalLink will no be processed, 
only of Link...

please help *argh*

cheers
peter

Might be misunderstanding you, but you should be able to do simply:
ExternalLink.new instead of Link.new(:type =>ExternalLink.to_s)

As far as the create goes, I''ve guessing your MyNavigation model has a 
has_many :links, and so there will be a links method for instances of 
this model, but no method called external_links.

I would think however you could do something like (and haven''t tested 
this):

ext_link = ExternalLink.new(:url => "link_details")

my_navigation << ext_link

HTH

Pete wrote:
> Hi,
>
> is there a way to instantiate a _concrete_ subtype from within an 
> ActiveRecord collection?
>
> Example:
>
> class Link < ActiveRecord::Base
> end
>
> class InternalLink < Link
> end
>
> class ExternalLink < Link
> end
>
> internal_link = my_navigation.links.create_[xxxxxxx]
> external_link = my_navigation.links.create_[xxxxxxxx]
>
> the [xxx] is what I am missing...
>
> I could do this
>
> external_link = my_navigation.links.create(:type => ExternalLink.to_s)
>
> but in this case the validations of ExternalLink will no be processed, 
> only of Link...
>
> please help *argh*
>
> cheers
> peter
>
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