Fix :content_type_extension when a style :format is specified.

lib/paperclip/interpolations.rb

@@ -97,9 +97,12 @@ module Paperclip
         File.extname(attachment.original_filename).gsub(/^\.+/, "")
     end
 
-    # Returns an extension based on the content type. e.g. "jpeg" for "image/jpeg".
+    # Returns an extension based on the content type. e.g. "jpeg" for
+    # "image/jpeg". If the style has a specified format, it will override the
+    # content-type detection.
+    #
     # Each mime type generally has multiple extensions associated with it, so
-    # if the extension from teh original filename is one of these extensions,
+    # if the extension from the original filename is one of these extensions,
     # that extension is used, otherwise, the first in the list is used.
     def content_type_extension attachment, style_name
       mime_type = MIME::Types[attachment.content_type]
@@ -110,7 +113,10 @@ module Paperclip
       end
 
       original_extension = extension(attachment, style_name)
-      if extensions_for_mime_type.include? original_extension
+      style = attachment.styles[style_name.to_s.to_sym]
+      if style && style[:format]
+        style[:format].to_s
+      elsif extensions_for_mime_type.include? original_extension
         original_extension
       elsif !extensions_for_mime_type.empty?
         extensions_for_mime_type.first

test/interpolations_test.rb

@@ -56,6 +56,7 @@ class InterpolationsTest < Test::Unit::TestCase
   should "return the extension of the file based on the content type" do
     attachment = mock
     attachment.expects(:content_type).returns('image/jpeg')
+    attachment.expects(:styles).returns({})
     interpolations = Paperclip::Interpolations
     interpolations.expects(:extension).returns('random')
     assert_equal "jpeg", interpolations.content_type_extension(attachment, :style)
@@ -64,6 +65,7 @@ class InterpolationsTest < Test::Unit::TestCase
   should "return the original extension of the file if it matches a content type extension" do
     attachment = mock
     attachment.expects(:content_type).returns('image/jpeg')
+    attachment.expects(:styles).returns({})
     interpolations = Paperclip::Interpolations
     interpolations.expects(:extension).returns('jpe')
     assert_equal "jpe", interpolations.content_type_extension(attachment, :style)
@@ -72,11 +74,21 @@ class InterpolationsTest < Test::Unit::TestCase
   should "return the latter half of the content type of the extension if no match found" do
     attachment = mock
     attachment.expects(:content_type).at_least_once().returns('not/found')
+    attachment.expects(:styles).returns({})
     interpolations = Paperclip::Interpolations
     interpolations.expects(:extension).returns('random')
     assert_equal "found", interpolations.content_type_extension(attachment, :style)
   end
 
+  should "return the format if defined in the style, ignoring the content type" do
+    attachment = mock
+    attachment.expects(:content_type).returns('image/jpeg')
+    attachment.expects(:styles).returns({:style => {:format => "png"}})
+    interpolations = Paperclip::Interpolations
+    interpolations.expects(:extension).returns('random')
+    assert_equal "png", interpolations.content_type_extension(attachment, :style)
+  end
+
   should "be able to handle numeric style names" do
     attachment = mock(
       :styles => {:"4" => {:format => :expected_extension}}