Added support for created_at field

lib/paperclip/attachment.rb

@@ -99,6 +99,7 @@ module Paperclip
       instance_write(:content_type,    file.content_type.to_s.strip)
       instance_write(:file_size,       file.size)
       instance_write(:fingerprint,     file.fingerprint) if instance_respond_to?(:fingerprint)
+      instance_write(:created_at,      Time.now) if has_enabled_but_unset_created_at?
       instance_write(:updated_at,      Time.now)
 
       @dirty = true
@@ -254,6 +255,15 @@ module Paperclip
       instance_read(:content_type)
     end
 
+    # Returns the creation time of the file as originally assigned, and
+    # lives in the <attachment>_created_at attribute of the model.
+    def created_at
+      if able_to_store_created_at?
+        time = instance_read(:created_at)
+        time && time.to_f.to_i
+      end
+    end
+
     # Returns the last modified time of the file as originally assigned, and
     # lives in the <attachment>_updated_at attribute of the model.
     def updated_at
@@ -429,6 +439,7 @@ module Paperclip
       instance_write(:content_type, nil)
       instance_write(:file_size, nil)
       instance_write(:fingerprint, nil)
+      instance_write(:created_at, nil) if has_enabled_but_unset_created_at?
       instance_write(:updated_at, nil)
     end
 
@@ -453,5 +464,15 @@ module Paperclip
         filename
       end
     end
+
+    # Check if attachment database table has a created_at field
+    def able_to_store_created_at?
+      @instance.respond_to?("#{name}_created_at".to_sym)
+    end
+
+    # Check if attachment database table has a created_at field which is not yet set
+    def has_enabled_but_unset_created_at?
+      able_to_store_created_at? && !instance_read(:created_at)
+    end
   end
 end

test/attachment_test.rb

@@ -1101,6 +1101,41 @@ class AttachmentTest < Test::Unit::TestCase
       assert_equal File.size(@file), @dummy.avatar.size
     end
 
+    should "return the right value when sent #avatar_file_size" do
+      @dummy.avatar = @file
+      assert_equal File.size(@file), @dummy.avatar.size
+    end
+
+    context "and avatar_created_at column" do
+      setup do
+        ActiveRecord::Base.connection.add_column :dummies, :avatar_created_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 creation time when sent #avatar_created_at" do
+        now = Time.now
+        Time.stubs(:now).returns(now)
+        @dummy.avatar = @file
+        assert_equal now.to_i, @dummy.avatar.created_at
+      end
+
+      should "return the creation time when sent #avatar_created_at and the entry has been updated" do
+        creation = 2.hours.ago
+        now = Time.now
+        Time.stubs(:now).returns(creation)
+        @dummy.avatar = @file
+        Time.stubs(:now).returns(now)
+        @dummy.avatar = @file
+        assert_equal creation.to_i, @dummy.avatar.created_at
+        assert_not_equal now.to_i, @dummy.avatar.created_at
+      end
+    end
+
     context "and avatar_updated_at column" do
       setup do
         ActiveRecord::Base.connection.add_column :dummies, :avatar_updated_at, :timestamp