Fix for #122, #121 and #175 on Rails 4 branch

lib/paranoia.rb

@@ -154,7 +154,7 @@ def restore_associated_records
           association_find_conditions = { association_foreign_key => self.id }
         end
 
-        association_class = Object.const_get(association_class_name)
+        association_class = association_class_name.constantize
         if association_class.paranoid?
           association_class.only_deleted.where(association_find_conditions).first.try!(:restore, recursive: true)
         end
@@ -237,3 +237,16 @@ def paranoia_sentinel_value
 end
 
 require 'paranoia/rspec' if defined? RSpec
+
+module ActiveRecord
+  module Validations
+    class UniquenessValidator < ActiveModel::EachValidator
+      protected
+      def build_relation_with_paranoia(klass, table, attribute, value)
+        relation = build_relation_without_paranoia(klass, table, attribute, value)
+        relation.and(klass.arel_table[klass.paranoia_column].eq(nil))
+      end
+      alias_method_chain :build_relation, :paranoia
+    end
+  end
+end

test/paranoia_test.rb

@@ -28,7 +28,7 @@ def setup!
     'fail_callback_models' => 'deleted_at DATETIME',
     'related_models' => 'parent_model_id INTEGER, parent_model_with_counter_cache_column_id INTEGER, deleted_at DATETIME',
     'asplode_models' => 'parent_model_id INTEGER, deleted_at DATETIME',
-    'employers' => 'deleted_at DATETIME',
+    'employers' => 'name VARCHAR(32), deleted_at DATETIME',
     'employees' => 'deleted_at DATETIME',
     'jobs' => 'employer_id INTEGER NOT NULL, employee_id INTEGER NOT NULL, deleted_at DATETIME',
     'custom_column_models' => 'destroyed_at DATETIME',
@@ -685,6 +685,19 @@ def test_observers_not_notified_if_not_supported
     # essentially, we're just ensuring that this doesn't crash
   end
 
+  def test_validates_uniqueness_only_checks_non_deleted_records
+    a = Employer.create!(name: "A")
+    a.destroy
+    b = Employer.new(name: "A")
+    assert b.valid?
+  end
+
+  def test_validates_uniqueness_still_works_on_non_deleted_records
+    a = Employer.create!(name: "A")
+    b = Employer.new(name: "A")
+    refute b.valid?
+  end
+
   def test_i_am_the_destroyer
     expected = %Q{
       Sharon: "There should be a method called I_AM_THE_DESTROYER!"
@@ -909,6 +922,7 @@ def set_after_commit_on_destroy_callback_called
 
 class Employer < ActiveRecord::Base
   acts_as_paranoid
+  validates_uniqueness_of :name
   has_many :jobs
   has_many :employees, :through => :jobs
 end