options to delete old versions of GridFileSystem files

lib/mongo/gridfs/grid_file_system.rb

@@ -53,6 +53,8 @@ module Mongo
     #   the content type will may be inferred from the filename extension if the mime-types gem can be
     #   loaded. Otherwise, the content type 'binary/octet-stream' will be used.
     # @options opts [Integer] (262144) :chunk_size size of file chunks in bytes.
+    # @options opts [Boolean] :delete_old (false) ensure that old versions of the file are deleted. This option
+    #  only work in 'w' mode.
     # @options opts [Boolean] :safe (false) When safe mode is enabled, the chunks sent to the server
     #   will be validated using an md5 hash. If validation fails, an exception will be raised.
     #
@@ -76,15 +78,23 @@ module Mongo
     #  @grid.open('image.jpg, 'w') do |f|
     #    f.write @file
     #  end
+    #
+    #  @return [Mongo::GridIO]
     def open(filename, mode, opts={})
       opts.merge!(default_grid_io_opts(filename))
+      del  = opts.delete(:delete_old) && mode == 'w'
       file = GridIO.new(@files, @chunks, filename, mode, opts)
       return file unless block_given?
       result = nil
       begin
         result = yield file
       ensure
-        file.close
+        id = file.close
+        if del
+          self.delete do
+            @files.find({'filename' => filename, '_id' => {'$ne' => id}}, :fields => ['_id'])
+          end
+        end
       end
       result
     end
@@ -94,9 +104,15 @@ module Mongo
     #
     # @param [String] filename
     #
+    # @yield [] pass a block that returns an array of documents to be deleted.
+    #
     # @return [Boolean]
-    def delete(filename)
+    def delete(filename=nil)
+      if block_given?
+        files = yield
+      else
         files = @files.find({'filename' => filename}, :fields => ['_id'])
+      end
       files.each do |file|
         @files.remove({'_id' => file['_id']})
         @chunks.remove({'files_id' => file['_id']})

lib/mongo/gridfs/grid_io.rb

@@ -163,16 +163,16 @@ module Mongo
     # This method will be invoked automatically when
     # on GridIO#open is passed a block. Otherwise, it must be called manually.
     #
-    # @return [True]
+    # @return [Mongo::ObjectID]
     def close
       if @mode[0] == ?w
         if @current_chunk['n'].zero? && @chunk_position.zero?
           warn "Warning: Storing a file with zero length."
         end
         @upload_date = Time.now.utc
-        @files.insert(to_mongo_object)
+        id = @files.insert(to_mongo_object)
       end
-      true
+      id
     end
 
     def inspect

test/grid_file_system_test.rb

@@ -109,9 +109,9 @@ class GridFileSystemTest < Test::Unit::TestCase
        context "and on a second overwrite" do
          setup do
            sleep(2)
-           new_data = "NEW" * 1000
+           @new_data = "NEW" * 1000
            @grid.open('sample', 'w') do |f|
-             f.write new_data
+             f.write @new_data
            end
 
            @ids = @db['fs.files'].find({'filename' => 'sample'}).map {|file| file['_id']}
@@ -127,6 +127,18 @@ class GridFileSystemTest < Test::Unit::TestCase
            assert_equal 0, @db['fs.files'].find({'filename' => 'sample'}).count
            assert_equal 0, @db['fs.chunks'].find({'files_id' => {'$in' => @ids}}).count
          end
+
+         should "delete old versions on write with :delete_old is passed in" do
+           @grid.open('sample', 'w', :delete_old => true) do |f|
+             f.write @new_data
+           end
+           @new_ids = @db['fs.files'].find({'filename' => 'sample'}).map {|file| file['_id']}
+           assert_equal 1, @new_ids.length
+           id = @new_ids.first
+           assert !@ids.include?(id)
+           assert_equal 1, @db['fs.files'].find({'filename' => 'sample'}).count
+           assert_equal 1, @db['fs.chunks'].find({'files_id' => id}).count
+         end
        end
      end
    end