Use a separate model to handle GPG subkeys

app/models/gpg_key.rb

@@ -10,7 +10,7 @@ class GpgKey < ActiveRecord::Base
   belongs_to :user
   belongs_to :parent, class_name: 'GpgKey'
   has_many :gpg_signatures
-  has_many :subkeys, class_name: 'GpgKey', foreign_key: :parent_id, dependent: :destroy
+  has_many :subkeys, class_name: 'GpgKeySubkey'
   validates :user, presence: true

app/models/gpg_key_subkey.rb

+class GpgKeySubkey < ActiveRecord::Base
+  belongs_to :gpg_key
+end

db/migrate/20170926050624_add_parent_id_to_gpg_keys.rb

-# See http://doc.gitlab.com/ce/development/migration_style_guide.html
-# for more information on how to write migrations for GitLab.
-
-class AddParentIdToGpgKeys < ActiveRecord::Migration
-  DOWNTIME = false
-
-  def change
-    add_column :gpg_keys, :parent_id, :integer
-  end
-end

db/migrate/20170927161718_create_gpg_key_subkeys.rb

+class CreateGpgKeySubkeys < ActiveRecord::Migration
+  def change
+    create_table :gpg_key_subkeys do |t|
+      t.binary :keyid
+      t.binary :fingerprint
+      t.references :gpg_key, null: false, index: true, foreign_key: { on_delete: :cascade }
+    end
+  end
+end

db/schema.rb

@@ -579,6 +579,14 @@ ActiveRecord::Schema.define(version: 20171004121444) do
   add_index "forked_project_links", ["forked_to_project_id"], name: "index_forked_project_links_on_forked_to_project_id", unique: true, using: :btree
+  create_table "gpg_key_subkeys", force: :cascade do |t|
+    t.binary "keyid"
+    t.binary "fingerprint"
+    t.integer "gpg_key_id", null: false
+  end
+
+  add_index "gpg_key_subkeys", ["gpg_key_id"], name: "index_gpg_key_subkeys_on_gpg_key_id", using: :btree
+
   create_table "gpg_keys", force: :cascade do |t|
     t.datetime_with_timezone "created_at", null: false
     t.datetime_with_timezone "updated_at", null: false
@@ -586,7 +594,6 @@ ActiveRecord::Schema.define(version: 20171004121444) do
     t.binary "primary_keyid"
     t.binary "fingerprint"
     t.text "key"
-    t.integer "parent_id"
   end
   add_index "gpg_keys", ["fingerprint"], name: "index_gpg_keys_on_fingerprint", unique: true, using: :btree
@@ -1727,6 +1734,7 @@ ActiveRecord::Schema.define(version: 20171004121444) do
   add_foreign_key "events", "projects", on_delete: :cascade
   add_foreign_key "events", "users", column: "author_id", name: "fk_edfd187b6f", on_delete: :cascade
   add_foreign_key "forked_project_links", "projects", column: "forked_to_project_id", name: "fk_434510edb0", on_delete: :cascade
+  add_foreign_key "gpg_key_subkeys", "gpg_keys", on_delete: :cascade
   add_foreign_key "gpg_keys", "users", on_delete: :cascade
   add_foreign_key "gpg_signatures", "gpg_keys", on_delete: :nullify
   add_foreign_key "gpg_signatures", "projects", on_delete: :cascade