Add support for accepts_attachments_for method

lib/refile/mongoid/attachment.rb

@@ -27,7 +27,49 @@ def attachment(name, raise_errors: false, **options)
             end
           end
         end
-
+      end
+
+      def accepts_attachments_for(association_name, attachment: :file, append: false)
+        association = reflect_on_association(association_name)
+        name = "#{association_name}_#{attachment.to_s.pluralize}"
+
+        mod = Module.new do
+          define_method :"#{name}_attachment_definition" do
+            association.klass.send("#{attachment}_attachment_definition")
+          end
+
+          define_method :"#{name}_data" do
+            if send(association_name).all? { |record| record.send("#{attachment}_attacher").valid? }
+              send(association_name).map(&:"#{attachment}_data").select(&:present?)
+            end
+          end
+
+          define_method :"#{name}" do
+            send(association_name).map(&attachment)
+          end
+
+          define_method :"#{name}=" do |files|
+            cache, files = files.partition { |file| file.is_a?(String) }
+
+            cache = Refile.parse_json(cache.first)
+
+            if not append and (files.present? or cache.present?)
+              send("#{association_name}=", [])
+            end
+
+            if files.empty? and cache.present?
+              cache.select(&:present?).each do |file|
+                send(association_name).build(attachment => file.to_json)
+              end
+            else
+              files.select(&:present?).each do |file|
+                send(association_name).build(attachment => file)
+              end
+            end
+          end
+        end
+
+        include mod
       end
     end
   end

refile-mongoid.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |gem|
   gem.require_path  = "lib"
 
   gem.add_dependency "refile", "~> 0.5"
-  gem.add_dependency 'mongoid', '~> 4.0'
+  gem.add_dependency 'mongoid', '>= 4.0'
 
   gem.add_development_dependency "rake", "~> 10.0"
   gem.add_development_dependency "rspec", "~> 3.1"