Prevent destruction if HABTM relation isnt empty

Question

    class Annex
      has_and_belongs_to_many: :documents
    end

    class Document
      has_and_belongs_to_many: :annexes
    end

I want to implement this behavior: if the annex is associated to at least one document, it shouldn't be destroyed.

Is there a easy rails way of doing this or will I have to make a work around this?

Will I have to use a before_destroy method or something like that?

Possible duplicate: http://stackoverflow.com/questions/2799746/habtm-relationship-does-not-support-dependent-option — Arjan, Jan 07 '14 at 21:26
Actually what I want to do is the opposite of that question, he wants to destroy I want to prevent destruction — Rafael Ramos Bravin, Jan 07 '14 at 21:29

score 1 · Accepted Answer · answered Jan 07 '14 at 21:49

1

Do something like this:

class Annex < ActiveRecord::Base
  has_and_belongs_to_many :documents
  before_destroy { raise "Can't destroy Annex, because it's still associated to 1 or more documents" if documents.any? }
end

answered Jan 07 '14 at 21:49

Arjan

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I see, so rails can't handle it with a relation option after all. But this seems dry enough, thanks. – Rafael Ramos Bravin Jan 07 '14 at 22:07

Prevent destruction if HABTM relation isnt empty

1 Answers1