Redmine 6 compatibility: update models to inherit from ApplicationRecord

Author: nanego

app/models/core_field.rb

@@ -1,4 +1,4 @@
-class CoreField < ActiveRecord::Base
+class CoreField < ApplicationRecord
   include Redmine::SafeAttributes
 
   has_and_belongs_to_many :roles, :join_table => "core_fields_roles", :foreign_key => "core_field_id"

init.rb

@@ -18,3 +18,10 @@
                          'display_custom_fields_first' => 'true' },
            :partial => 'settings/redmine_plugin_customize_core_fields'
 end
+
+# Support for Redmine 5
+if Redmine::VERSION::MAJOR < 6
+  class ApplicationRecord < ActiveRecord::Base
+    self.abstract_class = true
+  end
+end