Adds a class for managing content type detection

lib/paperclip.rb

@@ -40,6 +40,7 @@ require 'paperclip/attachment'
 require 'paperclip/attachment_options'
 require 'paperclip/storage'
 require 'paperclip/callbacks'
+require 'paperclip/content_type_detector'
 require 'paperclip/glue'
 require 'paperclip/errors'
 require 'paperclip/missing_attachment_styles'

lib/paperclip/content_type_detector.rb

+module Paperclip
+  class ContentTypeDetector
+    def initialize(filename)
+      @filename = filename
+    end
+
+    def detect
+      if !match?
+        type_from_file_command
+      elsif !multiple?
+        possible_types.first
+      else
+        best_type_match
+      end.to_s
+    end
+
+    private
+
+    def possible_types
+      @possible_types ||= MIME::Types.type_for(@filename)
+    end
+
+    def match?
+      possible_types.length > 0
+    end
+
+    def multiple?
+      possible_types.length > 1
+    end
+
+    def best_type_match
+      official_types = possible_types.reject {|type| type.content_type.match(/\/x-/) }
+      (official_types.first || possible_types.first).content_type
+    end
+
+    def type_from_file_command
+      # On BSDs, `file` doesn't give a result code of 1 if the file doesn't exist.
+      type = Paperclip.run("file", "-b --mime :file", :file => @filename)
+      if type.match(/\(.*?\)/)
+        type = "application/octet-stream"
+      end
+      type.split(/[:;\s]+/)[0]
+    end
+
+  end
+end

lib/paperclip/io_adapters/abstract_adapter.rb

@@ -23,23 +23,5 @@ module Paperclip
       FileUtils.cp(src.path, destination.path)
       destination
     end
-
-    def best_content_type_option(types)
-      best = types.reject {|type| type.content_type.match(/\/x-/) }
-      if best.size == 0
-        types.first.content_type
-      else
-        best.first.content_type
-      end
-    end
-
-    def type_from_file_command
-      # On BSDs, `file` doesn't give a result code of 1 if the file doesn't exist.
-      type = (File.extname(self.path.to_s)).downcase
-      type = "octet-stream" if type.empty?
-      mime_type = Paperclip.run("file", "-b --mime :file", :file => self.path).split(/[:;\s]+/)[0]
-      mime_type = "application/x-#{type}" if mime_type.match(/\(.*?\)/)
-      mime_type
-    end
   end
 end

lib/paperclip/io_adapters/file_adapter.rb

@@ -11,20 +11,9 @@ module Paperclip
       @original_filename = @target.original_filename if @target.respond_to?(:original_filename)
       @original_filename ||= File.basename(@target.path)
       @tempfile = copy_to_tempfile(@target)
-      @content_type = calculate_content_type
+      @content_type = ContentTypeDetector.new(@target.path).detect
       @size = File.size(@target)
     end
-
-    def calculate_content_type
-      types = MIME::Types.type_for(original_filename)
-      if types.length == 0
-        type_from_file_command
-      elsif types.length == 1
-        types.first.content_type
-      else
-        best_content_type_option(types)
-      end
-    end
   end
 end
 

test/content_type_detector_test.rb

+require './test/helper'
+
+class ContentTypeDetectorTest < Test::Unit::TestCase
+  context 'given a name' do
+    should 'return a content type based on that name' do
+      @filename = "/path/to/something.jpg"
+      assert_equal "image/jpeg", Paperclip::ContentTypeDetector.new(@filename).detect
+    end
+
+    should 'return a content type based on the content of the file' do
+      tempfile = Tempfile.new("something")
+      tempfile.write("This is a file.")
+      tempfile.rewind
+
+      assert_equal "text/plain", Paperclip::ContentTypeDetector.new(tempfile.path).detect
+    end
+
+    should 'return a sensible default if something goes wrong' do
+      @filename = "/path/to/something"
+      assert_equal "application/octet-stream", Paperclip::ContentTypeDetector.new(@filename).detect
+    end
+
+    should 'let errors raise if something blows up' do
+      Paperclip.stubs(:run).raises(Cocaine::CommandLineError.new)
+      @filename = "/path/to/something"
+      assert_raises(Cocaine::CommandLineError) do
+        Paperclip::ContentTypeDetector.new(@filename).detect
+      end
+    end
+  end
+end