Fields other than <name>_file_name are not required for operation.

lib/paperclip/attachment.rb

@@ -62,7 +62,6 @@ module Paperclip
 
       if uploaded_file.is_a?(Paperclip::Attachment)
         uploaded_file = uploaded_file.to_file(:original)
-        close_uploaded_file = true if uploaded_file.respond_to?(:close)
       end
 
       return nil unless valid_assignment?(uploaded_file)
@@ -89,7 +88,6 @@ module Paperclip
       # Reset the file size if the original file was reprocessed.
       instance_write(:file_size, uploaded_file.size.to_i)
     ensure
-      uploaded_file.close if close_uploaded_file
       validate
     end
 
@@ -154,6 +152,10 @@ module Paperclip
       instance_read(:file_name)
     end
 
+    def content_type
+      instance_read(:content_type)
+    end
+    
     def updated_at
       time = instance_read(:updated_at)
       time && time.to_i
@@ -193,7 +195,6 @@ module Paperclip
     # again.
     def reprocess!
       new_original = Tempfile.new("paperclip-reprocess")
-      new_original.binmode
       if old_original = to_file(:original)
         new_original.write( old_original.read )
         new_original.rewind
@@ -214,11 +215,15 @@ module Paperclip
     end
 
     def instance_write(attr, value)
-      instance.send(:"#{name}_#{attr}=", value)
+      setter = :"#{name}_#{attr}="
+      responds = instance.respond_to?(setter)
+      instance.send(setter, value) if responds || attr.to_s == "file_name"
     end
 
     def instance_read(attr)
-      instance.send(:"#{name}_#{attr}")
+      getter = :"#{name}_#{attr}"
+      responds = instance.respond_to?(getter)
+      instance.send(getter) if responds || attr.to_s == "file_name"
     end
 
     private

test/attachment_test.rb

@@ -367,4 +367,61 @@ class AttachmentTest < Test::Unit::TestCase
       end
     end
   end
+
+  context "An attachment with only a avatar_file_name column" do
+    setup do
+      ActiveRecord::Base.connection.create_table :dummies, :force => true do |table|
+        table.column :avatar_file_name, :string
+      end
+      rebuild_class
+      @dummy = Dummy.new
+      @file = File.new(File.join(File.dirname(__FILE__), "fixtures", "5k.png"), 'rb')
+    end
+
+    should "not error when assigned an attachment" do
+      assert_nothing_raised { @dummy.avatar = @file }
+    end
+
+    should "return nil when sent #avatar_updated_at" do
+      @dummy.avatar = @file
+      assert_nil @dummy.avatar.updated_at
+    end
+
+    context "and avatar_updated_at column" do
+      setup do
+        ActiveRecord::Base.connection.add_column :dummies, :avatar_updated_at, :timestamp
+        rebuild_class
+        @dummy = Dummy.new
+      end
+
+      should "not error when assigned an attachment" do
+        assert_nothing_raised { @dummy.avatar = @file }
+      end
+
+      should "return the right value when sent #avatar_updated_at" do
+        now = Time.now
+        Time.stubs(:now).returns(now)
+        @dummy.avatar = @file
+        assert_equal now.to_i, @dummy.avatar.updated_at
+      end
+    end
+
+    context "and avatar_content_type column" do
+      setup do
+        ActiveRecord::Base.connection.add_column :dummies, :avatar_content_type, :string
+        rebuild_class
+        @dummy = Dummy.new
+      end
+
+      should "not error when assigned an attachment" do
+        assert_nothing_raised { @dummy.avatar = @file }
+      end
+
+      should "return the right value when sent #avatar_content_type" do
+        @dummy.avatar = @file
+        assert_equal "image/png", @dummy.avatar.content_type
+      end
+    end
+
+  end
 end

test/helper.rb

@@ -35,7 +35,10 @@ def rebuild_model options = {}
     table.column :avatar_file_size, :integer
     table.column :avatar_updated_at, :datetime
   end
+  rebuild_class options
+end
 
+def rebuild_class options = {}
   ActiveRecord::Base.send(:include, Paperclip)
   Object.send(:remove_const, "Dummy") rescue nil
   Object.const_set("Dummy", Class.new(ActiveRecord::Base))