CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-3
Tim Kretschmer
Tim Kretschmer

Reputation: 2280

has_many IF conditions

I have Advertisements which can have ladyies, but only if the type is a "club".

Is there a rails-way to do that? especially with not creating lady objects? Do I have to check a lady object, before creating, if her parent is type=club?

class Advertisement < ActiveRecord::Base

  validates_inclusion_of :type, in: %w(club lady)

  has_many :ladies, :dependent=>:destroy

  #only have ladies if the club =
  def ladies 
    return nil unless type == "club"
    super    
  end

end

I'm using Rails 3.2.

Upvotes: 3

Views: 2868

Answers (3)

charlysisto
charlysisto

Reputation: 3700

It seems all this is mixing composition (has_many) with inheritance (lady < advertisement) which doesn't make much sense (technically and conceptually). If this is the case and you are not using Lady and Club objects, you should at least rename the type to ad_type...

Assuming you're making a self referential join you'll then need a club_id column :

class Advertisement < ActiveRecord::Base
   has_many :ladies, -> {where(type: 'club')}, class_name: "Advertisment"
 end

Upvotes: 0

Rimian
Rimian

Reputation: 38418

Perhaps using active record association extensions: (using proxy_association.owner)

http://guides.rubyonrails.org/association_basics.html#association-extensions

module LadiesAtClub
  def at_club
    # you may need to iterate over an array or something here...
    proxy_association.owner.type == 'club'
  end
end

class Advertisement < ActiveRecord::Base
  has_many :ladies :extend => LadiesAtClub
end

Upvotes: 0

Valery Kvon
Valery Kvon

Reputation: 4496

The Rails way to do that is STI:

 class Advertisement < ActiveRecord::Base
 end

 class LadyAd < Advertisement
   has_many :ladies, :dependent=>:destroy
 end

And only LadyAd object able to have ladies.

Upvotes: 3

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