mongo-ruby-driver/lib/mongo/gridfs/grid_file_system.rb

132 lines
4.7 KiB
Ruby

# --
# 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
# A file store built on the GridFS specification featuring
# an API and behavior similar to that of a traditional file system.
class GridFileSystem
# Initialize a new Grid instance, consisting of a MongoDB database
# and a filesystem prefix if not using the default.
#
# @param [Mongo::DB] db a MongoDB database.
# @param [String] fs_name A name for the file system. The default name, based on
# the specification, is 'fs'.
def initialize(db, fs_name=Grid::DEFAULT_FS_NAME)
raise MongoArgumentError, "db must be a Mongo::DB." unless db.is_a?(Mongo::DB)
@db = db
@files = @db["#{fs_name}.files"]
@chunks = @db["#{fs_name}.chunks"]
@fs_name = fs_name
@default_query_opts = {:sort => [['filename', 1], ['uploadDate', -1]], :limit => 1}
@files.create_index([['filename', 1], ['uploadDate', -1]])
@chunks.create_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]], :unique => true)
end
# Open a file for reading or writing. Note that the options for this method only apply
# when opening in 'w' mode.
#
# @param [String] filename the name of the file.
# @param [String] mode either 'r' or 'w' for reading from
# 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
# 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,
# 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.
#
# @example
#
# # Store the text "Hello, world!" in the grid file system.
# @grid = GridFileSystem.new(@db)
# @grid.open('filename', 'w') do |f|
# f.write "Hello, world!"
# end
#
# # Output "Hello, world!"
# @grid = GridFileSystem.new(@db)
# @grid.open('filename', 'r') do |f|
# puts f.read
# end
#
# # Write a file on disk to the GridFileSystem
# @file = File.open('image.jpg')
# @grid = GridFileSystem.new(@db)
# @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
id = file.close
if del
self.delete do
@files.find({'filename' => filename, '_id' => {'$ne' => id}}, :fields => ['_id'])
end
end
end
result
end
# Delete the file with the given filename. Note that this will delete
# all versions of the file.
#
# @param [String] filename
#
# @yield [] pass a block that returns an array of documents to be deleted.
#
# @return [Boolean]
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']})
end
end
alias_method :unlink, :delete
private
def default_grid_io_opts(filename=nil)
{:fs_name => @fs_name, :query => {'filename' => filename}, :query_opts => @default_query_opts}
end
end
end