Prepare Mastodon for Rails 6 (#15911)

* Fix misuse of foreign_type

* Fix use of removed "add_template_helper"

* Use response.media_type instead of response.content_type in tests

* Fix CSV export controller test on Rails 6

Rails 6 sets a "filename*" field in the Content-Disposition header to
explicitly encode the filename as UTF-8.

This changes checks the first part of the Content-Disposition header so
it matches in both Rails 5 and Rails 6.

* Fix emoji formatting with Rails 6

* Make emoji output more idiomatic and robust

* Switch from redis-rails gem to built-in Rails redis cache storage

1 files changed, 6 insertions, 6 deletions

diff --git a/app/models/notification.rb b/app/models/notification.rb
index 98a6a618f..3bf9dd483 100644
--- a/app/models/notification.rb
+++ b/app/models/notification.rb
@@ -49,12 +49,12 @@ class Notification < ApplicationRecord
   belongs_to :from_account, class_name: 'Account', optional: true
   belongs_to :activity, polymorphic: true, optional: true
 
-  belongs_to :mention,        foreign_type: 'Mention',       foreign_key: 'activity_id', optional: true
-  belongs_to :status,         foreign_type: 'Status',        foreign_key: 'activity_id', optional: true
-  belongs_to :follow,         foreign_type: 'Follow',        foreign_key: 'activity_id', optional: true
-  belongs_to :follow_request, foreign_type: 'FollowRequest', foreign_key: 'activity_id', optional: true
-  belongs_to :favourite,      foreign_type: 'Favourite',     foreign_key: 'activity_id', optional: true
-  belongs_to :poll,           foreign_type: 'Poll',          foreign_key: 'activity_id', optional: true
+  belongs_to :mention,        foreign_key: 'activity_id', optional: true
+  belongs_to :status,         foreign_key: 'activity_id', optional: true
+  belongs_to :follow,         foreign_key: 'activity_id', optional: true
+  belongs_to :follow_request, foreign_key: 'activity_id', optional: true
+  belongs_to :favourite,      foreign_key: 'activity_id', optional: true
+  belongs_to :poll,           foreign_key: 'activity_id', optional: true
 
   validates :type, inclusion: { in: TYPES }