Class | Mongo::GridFileSystem |
In: |
lib/mongo/gridfs/grid_file_system.rb
|
Parent: | Object |
A file store built on the GridFS specification featuring an API and behavior similar to that of a traditional file system.
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. @param [String] fs_name A name for the file system. The default name, based on
the specification, is 'fs'.
# File lib/mongo/gridfs/grid_file_system.rb, line 32 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} # Create indexes only if we're connected to a primary node. connection = @db.connection if (connection.class == Connection && connection.read_primary?) || (connection.class == ReplSetConnection && connection.primary) @files.create_index([['filename', 1], ['uploadDate', -1]]) @chunks.create_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]], :unique => true) end end
Delete the file with the given filename. Note that this will delete all versions of the file.
Be careful with this. Deleting a GridFS file can result in read errors if another process is attempting to read a file while it‘s being deleted. While the odds for this kind of race condition are small, it‘s important to be aware of.
@param [String] filename
@yield [] pass a block that returns an array of documents to be deleted.
@return [Boolean]
# File lib/mongo/gridfs/grid_file_system.rb, line 129 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
Open a file for reading or writing. Note that the options for this method only apply when opening in ‘w’ mode.
Note that arbitary metadata attributes can be saved to the file by passing them is as options.
@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
@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.
@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.
@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.
@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
# 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]
# File lib/mongo/gridfs/grid_file_system.rb, line 97 def open(filename, mode, opts={}) opts = opts.dup 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