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, 1 insertions, 1 deletions

diff --git a/db/migrate/20180528141303_fix_accounts_unique_index.rb b/db/migrate/20180528141303_fix_accounts_unique_index.rb
index 5d7b3c463..02813f363 100644
--- a/db/migrate/20180528141303_fix_accounts_unique_index.rb
+++ b/db/migrate/20180528141303_fix_accounts_unique_index.rb
@@ -37,7 +37,7 @@ class FixAccountsUniqueIndex < ActiveRecord::Migration[5.2]
       end
     end
 
-    duplicates = Account.connection.select_all('SELECT string_agg(id::text, \',\') AS ids FROM accounts GROUP BY lower(username), lower(domain) HAVING count(*) > 1').to_hash
+    duplicates = Account.connection.select_all('SELECT string_agg(id::text, \',\') AS ids FROM accounts GROUP BY lower(username), lower(domain) HAVING count(*) > 1').to_ary
 
     duplicates.each do |row|
       deduplicate_account!(row['ids'].split(','))