Use an Enumerator to move the ActiveRecord dependency into the schema…

… migration class

lib/paperclip/schema.rb

@@ -47,11 +47,26 @@ def drop_attached_file(*args)
       end
 
       def add_style(table_name, attachment_name, styles)
-        StyleAdder.run(table_name, attachment_name, styles)
+        StyleAdder.run(model_enumerator(table_name), attachment_name, styles)
       end
 
       def remove_style(table_name, attachment_name, style_name)
-        StyleRemover.run(table_name, attachment_name, style_name)
+        StyleRemover.run(model_enumerator(table_name), attachment_name, style_name)
+      end
+
+      private
+
+      def model_enumerator(table_name)
+        model_class(table_name).enum_for(:find_each)
+      end
+
+      def model_class(table_name)
+        model_class_name = table_name.to_s.singularize.camelize
+        begin
+          model_class_name.constantize
+        rescue NameError
+          raise ArgumentError, "found no model named #{model_class_name}"
+        end
       end
     end
 

lib/paperclip/style_migration.rb

@@ -2,28 +2,19 @@
 
 module Paperclip
   class StyleMigration
-    def self.run(table_name, attachment_name, *style_info)
-      new(model_class(table_name), attachment_name).run(*style_info)
+    def self.run(model_enumerator, attachment_name, *style_info)
+      new(model_enumerator, attachment_name).run(*style_info)
     end
 
-    def initialize(model_class, attachment_name)
-      @model_class = model_class
+    def initialize(model_enumerator, attachment_name)
+      @model_enumerator = model_enumerator
       @attachment_name = attachment_name
     end
 
     protected
 
-    def self.model_class(table_name)
-      model_class_name = table_name.to_s.singularize.camelize
-      begin
-        model_class_name.constantize
-      rescue NameError
-        raise ArgumentError, "found no model named #{model_class_name}"
-      end
-    end
-
     def each_attachment(&block)
-      @model_class.find_each do |model|
+      @model_enumerator.each do |model|
         block.call(attachment_for(model))
       end
     end

test/style_adder_test.rb

@@ -17,9 +17,11 @@ class StyleAdderTest < Test::Unit::TestCase
       Paperclip.reset_duplicate_clash_check!
     end
 
+    dummy_enumerator = Dummy.all
+
     RecordingProcessor.clear
 
-    Paperclip::StyleAdder.run :dummies, :avatar, large: '124x124'
+    Paperclip::StyleAdder.run dummy_enumerator, :avatar, large: '124x124'
 
     assert RecordingProcessor.has_processed?(large: '124x124')
     assert !RecordingProcessor.has_processed?(thumbnail: '24x24')

test/style_remover_test.rb

@@ -14,8 +14,9 @@ class StyleRemoverTest < Test::Unit::TestCase
 
     large_path = dummy.avatar.path(:large)
     original_path = dummy.avatar.path(:original)
+    dummy_enumerator = Dummy.all
 
-    Paperclip::StyleRemover.run(:dummy, :avatar, :large)
+    Paperclip::StyleRemover.run dummy_enumerator, :avatar, :large
 
     assert !File.exist?(large_path)
     assert File.exist?(original_path)