Manage transaction rollback

  When we try to create new active record object into transaction and meet rollback:
    database row will not be created but uploader has created file in folder and doen't remove it.

  I changed behavior: now we store file only after commit action. This true and for update action in transaction.

  Changes in spec/orm/activerecord_spec.rb:
    - Add tests which covers this flows
    - add cleaning 'public_path' folder.Cause we also works with 'spec/public/uploads' folder.

lib/carrierwave/orm/activerecord.rb

@@ -52,15 +52,24 @@ def mount_base(column, uploader=nil, options={}, &block)
       validates_processing_of column if uploader_option(column.to_sym, :validate_processing)
       validates_download_of column if uploader_option(column.to_sym, :validate_download)
 
-      after_save :"store_#{column}!"
       before_save :"write_#{column}_identifier"
       after_commit :"remove_#{column}!", :on => :destroy
-      after_commit :"mark_remove_#{column}_false", :on => :update
-
-      after_save :"store_previous_changes_for_#{column}"
-      after_commit :"remove_previously_stored_#{column}", :on => :update
+      after_commit :"after_create_#{column}", :on => :create
+      after_commit :"after_update_#{column}", :on => :update
 
       class_eval <<-RUBY, __FILE__, __LINE__+1
+        def after_update_#{column}
+          store_#{column}!
+          store_previous_changes_for_#{column}
+          remove_previously_stored_#{column}
+          mark_remove_#{column}_false
+        end
+
+        def after_create_#{column}
+          store_#{column}!
+          store_previous_changes_for_#{column}
+        end
+
         def #{column}=(new_file)
           column = _mounter(:#{column}).serialization_column
           if !(new_file.blank? && __send__(:#{column}).blank?)

spec/orm/activerecord_spec.rb

@@ -648,6 +648,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end
 
@@ -735,6 +736,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end
 
@@ -758,14 +760,53 @@ def filename
       Event.transaction do
         @event.image = stub_file('new.jpeg')
         @event.save
-        expect(File.exist?(public_path('uploads/new.jpeg'))).to be_truthy
         expect(File.exist?(public_path('uploads/old.jpeg'))).to be_truthy
         raise ActiveRecord::Rollback
       end
       expect(File.exist?(public_path('uploads/old.jpeg'))).to be_truthy
     end
   end
 
+  describe "#mount_uploader into transaction" do
+    before do
+      @uploader.version :thumb
+      reset_class("Event")
+      Event.mount_uploader(:image, @uploader)
+      @event = Event.new
+    end
+
+    after do
+      FileUtils.rm_rf(public_path("uploads"))
+      FileUtils.rm_rf(file_path("uploads"))
+    end
+
+    it "should not store file during rollback" do
+      Event.transaction do
+        @event.image = stub_file('new.jpeg')
+        @event.save
+
+        raise ActiveRecord::Rollback
+      end
+
+      expect(File.exist?(public_path('uploads/new.jpeg'))).to be_falsey
+    end
+
+    it "should not change file during rollback" do
+      @event.image = stub_file('old.jpeg')
+      @event.save
+
+      Event.transaction do
+        @event.image = stub_file('new.jpeg')
+        @event.save
+
+        raise ActiveRecord::Rollback
+      end
+
+      expect(File.exist?(public_path('uploads/new.jpeg'))).to be_falsey
+      expect(File.exist?(public_path('uploads/old.jpeg'))).to be_truthy
+    end
+  end
+
   describe '#mount_uploader removing old files with multiple uploaders' do
     before do
       @uploader = Class.new(CarrierWave::Uploader::Base)
@@ -783,6 +824,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end
 
@@ -826,6 +868,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end
 
@@ -1367,6 +1410,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end
 
@@ -1444,6 +1488,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end
 
@@ -1481,6 +1526,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end
 
@@ -1523,6 +1569,7 @@ def filename
     end
 
     after do
+      FileUtils.rm_rf(public_path("uploads"))
       FileUtils.rm_rf(file_path("uploads"))
     end