added Grid#exist? and GridFileSystem#exist? RUBY-122

lib/mongo.rb

@@ -40,6 +40,7 @@ require 'mongo/connection'
 require 'mongo/cursor'
 require 'mongo/db'
 require 'mongo/exceptions'
+require 'mongo/gridfs/grid_ext'
 require 'mongo/gridfs/grid'
 require 'mongo/gridfs/grid_io'
 require 'mongo/gridfs/grid_file_system'

lib/mongo/collection.rb

@@ -209,7 +209,7 @@ module Mongo
     #   run an fsync and/or wait for replication of the save (>= 1.5.1). See the options
     #   for DB#error.
     #
-    # @raises [OperationFailure] when :safe mode fails.
+    # @raise [OperationFailure] when :safe mode fails.
     #
     # @see DB#remove for options that can be passed to :safe.
     def save(doc, opts={})

lib/mongo/gridfs/grid.rb

@@ -18,6 +18,8 @@ module Mongo
 
   # Implementation of the MongoDB GridFS specification. A file store.
   class Grid
+    include GridExt::InstanceMethods
+
     DEFAULT_FS_NAME = 'fs'
 
     # Initialize a new Grid instance, consisting of a MongoDB database
@@ -44,15 +46,15 @@ module Mongo
     #
     # @param [String, #read] data a string or io-like object to store.
     #
-    # @options opts [String] :filename (nil) a name for the file.
-    # @options opts [Hash] :metadata ({}) any additional data to store with the file.
-    # @options opts [ObjectID] :_id (ObjectID) a unique id for
+    # @option opts [String] :filename (nil) a name for the file.
+    # @option opts [Hash] :metadata ({}) any additional data to store with the file.
+    # @option opts [ObjectID] :_id (ObjectID) a unique id for
     #   the file to be use in lieu of an automatically generated one.
-    # @options opts [String] :content_type ('binary/octet-stream') If no content type is specified,
+    # @option opts [String] :content_type ('binary/octet-stream') If no content type is specified,
     #   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] :safe (false) When safe mode is enabled, the chunks sent to the server
+    # @option opts [Integer] (262144) :chunk_size size of file chunks in bytes.
+    # @option 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.
     #
     # @return [Mongo::ObjectID] the file's id.

lib/mongo/gridfs/grid_ext.rb

@@ -0,0 +1,55 @@
+# --
+# Copyright (C) 2008-2010 10gen Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ++
+
+module Mongo
+  module GridExt
+    module InstanceMethods
+
+      # Check the existence of a file matching the given query selector.
+      #
+      # Note that this method can be used with both the Grid and GridFileSystem classes. Also
+      # keep in mind that if you're going to be performing lots of existence checks, you should
+      # keep an instance of Grid or GridFileSystem handy rather than instantiating for each existence
+      # check. Alternatively, simply keep a reference to the proper files collection and query that
+      # as needed. That's exactly how this methods works.
+      #
+      # @param [Hash] selector a query selector.
+      #
+      # @example
+      #
+      #   # Check for the existence of a given filename
+      #   @grid = GridFileSystem.new(@db)
+      #   @grid.exist?(:filename => 'foo.txt')
+      #
+      #   # Check for existence filename and content type
+      #   @grid = GridFileSystem.new(@db)
+      #   @grid.exist?(:filename => 'foo.txt', :content_type => 'image/jpg')
+      #
+      #   # Check for existence by _id
+      #   @grid = Grid.new(@db)
+      #   @grid.exist?(:_id => BSON::ObjectID.from_string('4bddcd24beffd95a7db9b8c8'))
+      #
+      #   # Check for existence by an arbitrary attribute.
+      #   @grid = Grid.new(@db)
+      #   @grid.exist?(:tags => {'$in' => ['nature', 'zen', 'photography']})
+      #
+      # @return [nil, Hash] either nil for the file's metadata as a hash.
+      def exist?(selector)
+        @files.find_one(selector)
+      end
+    end
+  end
+end

lib/mongo/gridfs/grid_file_system.rb

@@ -19,8 +19,9 @@ module Mongo
   # A file store built on the GridFS specification featuring
   # an API and behavior similar to that of a traditional file system.
   class GridFileSystem
+    include GridExt::InstanceMethods
 
-    # Initialize a new Grid instance, consisting of a MongoDB database
+    # Initialize a new GridFileSystem instance, consisting of a MongoDB database
     # and a filesystem prefix if not using the default.
     #
     # @param [Mongo::DB] db a MongoDB database.
@@ -51,17 +52,17 @@ module Mongo
     #   or writing to the file.
     # @param [Hash] opts see GridIO#new
     #
-    # @options opts [Hash] :metadata ({}) any additional data to store with the file.
-    # @options opts [ObjectID] :_id (ObjectID) a unique id for
+    # @option opts [Hash] :metadata ({}) any additional data to store with the file.
+    # @option opts [ObjectID] :_id (ObjectID) a unique id for
     #   the file to be use in lieu of an automatically generated one.
-    # @options opts [String] :content_type ('binary/octet-stream') If no content type is specified,
+    # @option opts [String] :content_type ('binary/octet-stream') If no content type is specified,
     #   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
+    # @option opts [Integer] (262144) :chunk_size size of file chunks in bytes.
+    # @option opts [Boolean] :delete_old (false) ensure that old versions of the file are deleted. This option
     #  only work in 'w' mode. Certain precautions must be taken when deleting GridFS files. See the notes under
     #  GridFileSystem#delete.
-    # @options opts [Boolean] :safe (false) When safe mode is enabled, the chunks sent to the server
+    # @option 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.
     #
     # @example

lib/mongo/gridfs/grid_io.rb

@@ -43,14 +43,14 @@ module Mongo
     # @option opts [Hash] :query a query selector used when opening the file in 'r' mode.
     # @option opts [Hash] :query_opts any query options to be used when opening the file in 'r' mode.
     # @option opts [String] :fs_name the file system prefix.
-    # @options opts [Integer] (262144) :chunk_size size of file chunks in bytes.
-    # @options opts [Hash] :metadata ({}) any additional data to store with the file.
-    # @options opts [ObjectID] :_id (ObjectID) a unique id for
+    # @option opts [Integer] (262144) :chunk_size size of file chunks in bytes.
+    # @option opts [Hash] :metadata ({}) any additional data to store with the file.
+    # @option opts [ObjectID] :_id (ObjectID) a unique id for
     #   the file to be use in lieu of an automatically generated one.
-    # @options opts [String] :content_type ('binary/octet-stream') If no content type is specified,
+    # @option opts [String] :content_type ('binary/octet-stream') If no content type is specified,
     #   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 [Boolean] :safe (false) When safe mode is enabled, the chunks sent to the server
+    # @option 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.
     def initialize(files, chunks, filename, mode, opts={})
       @files        = files

test/grid_file_system_test.rb

@@ -25,6 +25,15 @@ class GridFileSystemTest < Test::Unit::TestCase
         @grid = GridFileSystem.new(@db)
       end
 
+      should "return existence of the file" do
+        file = @grid.exist?(:filename => 'sample.file')
+        assert_equal 'sample.file', file['filename']
+      end
+
+      should "return nil if the file doesn't exist" do
+        assert_nil @grid.exist?(:filename => 'foo.file')
+      end
+
       should "read sample data" do
         data = @grid.open('sample.file', 'r') { |f| f.read }
         assert_equal data.length, @chunks_data.length

test/grid_test.rb

@@ -22,6 +22,15 @@ class GridTest < Test::Unit::TestCase
         @id   = @grid.put(@data, :filename => 'sample', :metadata => {'app' => 'photos'})
       end
 
+      should "check existence" do
+        file = @grid.exist?(:filename => 'sample')
+        assert_equal 'sample', file['filename']
+      end
+
+      should "return nil if it doesn't exist" do
+        assert_nil @grid.exist?(:metadata => 'foo')
+      end
+
       should "retrieve the stored data" do
         data = @grid.get(@id).data
         assert_equal @data, data

test/mongo_bson/bson_test.rb

@@ -369,7 +369,7 @@ class BSONTest < Test::Unit::TestCase
 
   # note we only test for _id here because in the general case we will
   # write duplicates for :key and "key". _id is a special case because
-  # we call has_key? to check for it's existance rather than just iterating
+  # we call has_key? to check for it's existence rather than just iterating
   # over it like we do for the rest of the keys. thus, things like
   # HashWithIndifferentAccess can cause problems for _id but not for other
   # keys. rather than require rails to test with HWIA directly, we do this