class Mongo::GridFileSystem

A file store built on the GridFS specification featuring an API and behavior similar to that of a traditional file system.

Public Class Methods

new(db, fs_name=Grid::DEFAULT_FS_NAME) click to toggle source

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 31
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

Public Instance Methods

delete(filename=nil) { || ... } click to toggle source

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 136
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
Also aliased as: unlink
open(filename, mode, opts={}) { |file| ... } click to toggle source

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.

@option opts [Integer] :versions (false) deletes all versions which exceed the number specified to

retain ordered by uploadDate. This option only works in 'w' mode. Certain precautions must be taken when 
deleting GridFS files. See the notes under GridFileSystem#delete.

@example

# Store the text "Hello, world!" in the grid file system.
@grid = Mongo::GridFileSystem.new(@db)
@grid.open('filename', 'w') do |f|
  f.write "Hello, world!"
end

# Output "Hello, world!"
@grid = Mongo::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 = Mongo::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 99
def open(filename, mode, opts={})
  opts = opts.dup
  opts.merge!(default_grid_io_opts(filename))
  if mode == 'w'
    versions = opts.delete(:versions)
    if opts.delete(:delete_old) || (versions && versions < 1)
      versions = 1
    end
  end
  file = GridIO.new(@files, @chunks, filename, mode, opts)
  return file unless block_given?
  result = nil
  begin
    result = yield file
  ensure
    id = file.close
    if versions
      self.delete do
        @files.find({'filename' => filename, '_id' => {'$ne' => id}}, :fields => ['_id'], :sort => ['uploadDate', -1], :skip => (versions - 1))
      end
    end
  end
  result
end

Private Instance Methods

default_grid_io_opts(filename=nil) click to toggle source
# File lib/mongo/gridfs/grid_file_system.rb, line 151
def default_grid_io_opts(filename=nil)
  {:fs_name => @fs_name, :query => {'filename' => filename}, :query_opts => @default_query_opts}
end