How to free up friendly_id slugs when destroying a record?

Question

My Page model has a slug column using FriendlyId, with the history option turned on.

I want to free slugs so that if a page with this slug is destroyed, then recreated, it can reuse the same slug.

Site.create(slug: "alpha") # => adds an entry into FriendlyId::Slug
Site.find_by(slug: "alpha").destroy # => Leaves an orphaned slug entry
Site.create(slug: "alpha") # Cannot reuse the old slug
Site.last.slug # "alpha-{uuid}"

Answer 1

You don't actually have to do anything.

FriendlyId's history module adds an association with the dependent: :destroy option anyways.

module FriendlyId
  module History
    module Configuration
      def dependent_value
        dependent.nil? ? :destroy : dependent
      end
    end
    # ....
    # Configures the model instance to use the History add-on.
    def self.included(model_class)
      model_class.class_eval do
        has_many :slugs, -> { order(id: :desc) }, **{
          as: :sluggable,
          dependent: @friendly_id_config.dependent_value,
          class_name: Slug.to_s
        }

        after_save :create_slug
      end
    end
    # ...
  end
end

If you want to change it there is a configuration option. It's just not documented besides a line comment in the configuration file. You can either add it to the initializer file or pass it to the friendly_id method.

Your "fix" is actually not doing anything except removing the ordering. Instead the issue is either a bug or just that your method of testing is flawed (it's not reproducable and destroy can fail).

There are actual passing tests in the gem that disprove the premise of the question.

class DependentDestroyTest < TestCaseClass
  include FriendlyId::Test

  class FalseManual < ActiveRecord::Base
    self.table_name = "manuals"

    extend FriendlyId
    friendly_id :name, use: :history, dependent: false
  end

  class DefaultManual < ActiveRecord::Base
    self.table_name = "manuals"

    extend FriendlyId
    friendly_id :name, use: :history
  end

  test "should allow disabling of dependent destroy" do
    transaction do
      assert FriendlyId::Slug.find_by_slug("foo").nil?
      l = FalseManual.create! name: "foo"
      assert FriendlyId::Slug.find_by_slug("foo").present?
      l.destroy
      assert FriendlyId::Slug.find_by_slug("foo").present?
    end
  end

  test "should dependently destroy by default" do
    transaction do
      assert FriendlyId::Slug.find_by_slug("baz").nil?
      l = DefaultManual.create! name: "baz"
      assert FriendlyId::Slug.find_by_slug("baz").present?
      l.destroy
      assert FriendlyId::Slug.find_by_slug("baz").nil?
    end
  end
end