Further preparation for Rails 6 (#15916)

* Use ActiveRecord::Result#to_ary instead of deprecated to_hash

They do the same thing, and to_hash has been removed from Rails 6.1

* Explicitly name polymorphic indexes to workaround a bug in Rails 6.1

cf. https://github.com/rails/rails/issues/41693

* Fix incorrect usage of “foreign_key” in migration script

* Use `ActiveModel::Errors#delete` instead of deprecated clear method

* Fix link headers tests on Rails 6.1

Rails 6.1 adds values to the Link header by default, thus it is not a
LinkHeader object anymore. Fix the test to parse the Link header instead
of assuming it is a LinkHeader.

1 files changed, 4 insertions, 4 deletions

diff --git a/db/migrate/20161006213403_rails_settings_migration.rb b/db/migrate/20161006213403_rails_settings_migration.rb
index 42875d7cb..9d565cb5c 100644
--- a/db/migrate/20161006213403_rails_settings_migration.rb
+++ b/db/migrate/20161006213403_rails_settings_migration.rb
@@ -7,12 +7,12 @@ end
 class RailsSettingsMigration < MIGRATION_BASE_CLASS
   def self.up
     create_table :settings do |t|
-      t.string     :var, :null => false
+      t.string     :var, null: false
       t.text       :value
-      t.references :target, :null => false, :polymorphic => true
-      t.timestamps :null => true
+      t.references :target, null: false, polymorphic: true, index: { name: 'index_settings_on_target_type_and_target_id' }
+      t.timestamps null: true
     end
-    add_index :settings, [ :target_type, :target_id, :var ], :unique => true
+    add_index :settings, [ :target_type, :target_id, :var ], unique: true
   end
 
   def self.down