Instantiate record in single table inheritance

Rails
1

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

2

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