From 0813616c9338e2b792c4a94b5d82aa2280c492e0 Mon Sep 17 00:00:00 2001
From: Oleg Pudeyev <oleg@bsdpower.com>
Date: Sun, 7 Feb 2016 20:48:29 -0500
Subject: [PATCH] Permit acts_as_paranoid to be given on abstract AR classes

Works around https://github.com/rails/rails/issues/10658
and https://github.com/rails/rails/issues/23413.
---
 lib/paranoia.rb       |  9 +++++++++
 test/paranoia_test.rb | 17 +++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/lib/paranoia.rb b/lib/paranoia.rb
index a6bc20d0..94ad97f3 100644
--- a/lib/paranoia.rb
+++ b/lib/paranoia.rb
@@ -221,7 +221,16 @@ def self.paranoia_scope
     end
     
     unless options[:without_default_scope]
+      # this default_scope declaration sets paranoia_sentinel_value
+      # in constructors of objects using Paranoia
       default_scope { paranoia_scope }
+      # this class method makes it possible to use acts_as_paranoid on
+      # abstract ActiveRecord classes, working around
+      # https://github.com/rails/rails/issues/10658 and
+      # https://github.com/rails/rails/issues/23413
+      def self.default_scope
+        paranoia_scope
+      end
     end
 
     before_restore {
diff --git a/test/paranoia_test.rb b/test/paranoia_test.rb
index a49a4d4e..21a5a554 100644
--- a/test/paranoia_test.rb
+++ b/test/paranoia_test.rb
@@ -41,6 +41,7 @@ def setup!
     'unparanoid_unique_models' => 'name VARCHAR(32), paranoid_with_unparanoids_id INTEGER',
     'active_column_models' => 'deleted_at DATETIME, active BOOLEAN',
     'active_column_model_with_uniqueness_validations' => 'name VARCHAR(32), deleted_at DATETIME, active BOOLEAN',
+    'paranoid_children' => 'deleted_at DATETIME',
     'without_default_scope_models' => 'deleted_at DATETIME'
   }.each do |table_name, columns_as_sql_string|
     ActiveRecord::Base.connection.execute "CREATE TABLE #{table_name} (id INTEGER NOT NULL PRIMARY KEY, #{columns_as_sql_string})"
@@ -936,6 +937,14 @@ def test_callbacks_for_counter_cache_column_update_on_really_destroy!
     end
   end
 
+  def test_abstract_intermediary
+    ParanoidChild.create!
+    # triggers https://github.com/rails/rails/issues/10658 /
+    # https://github.com/rails/rails/issues/23413
+    # if default_scope is specified as a closure instead of a class method
+    child = ParanoidChild.first
+  end
+
   private
   def get_featureful_model
     FeaturefulModel.new(:name => "not empty")
@@ -1208,3 +1217,11 @@ class ParanoidBelongsTo < ActiveRecord::Base
     belongs_to :paranoid_has_one
   end
 end
+
+class AbstractIntermediary < ActiveRecord::Base
+  self.abstract_class = true
+  acts_as_paranoid
+end
+
+class ParanoidChild < AbstractIntermediary
+end