Parent

Mongo::Grid

Implementation of the MongoDB GridFS specification. A file store.

Constants

DEFAULT_FS_NAME

Public Class Methods

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

Initialize a new Grid instance, consisting of a MongoDB database and a filesystem prefix if not using the default.

@core gridfs

@see GridFileSystem

# File lib/mongo/gridfs/grid.rb, line 15
def initialize(db, fs_name=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

  # This will create indexes only if we're connected to a primary node.
  connection = @db.connection
  begin
    @chunks.ensure_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]], :unique => true)
  rescue Mongo::ConnectionFailure
  end
end

Public Instance Methods

delete(id) click to toggle source

Delete a file from the store.

Note that 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 [] id

@return [Boolean]

# File lib/mongo/gridfs/grid.rb, line 90
def delete(id)
  @files.remove({"_id" => id})
  @chunks.remove({"files_id" => id})
end
get(id) click to toggle source

Read a file from the file store.

@param [] id the file's unique id.

@return [Mongo::GridIO]

# File lib/mongo/gridfs/grid.rb, line 76
def get(id)
  opts = {:query => {'_id' => id}}.merge!(default_grid_io_opts)
  GridIO.new(@files, @chunks, nil, 'r', opts)
end
put(data, opts={}) click to toggle source

Store a file in the file store. This method is designed only for writing new files; if you need to update a given file, first delete it using Grid#delete.

Note that arbitrary metadata attributes can be saved to the file by passing them in as options.

@param [String, read] data a string or io-like object to store.

@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.

@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 [String, Integer, Symbol] :w (1) Set write concern

Notes on write concern:  
   When :w > 0, the chunks sent to the server are validated using an md5 hash. 
   If validation fails, an exception will be raised.

@return [BSON::ObjectId] the file's id.

# File lib/mongo/gridfs/grid.rb, line 54
def put(data, opts={})
  begin
    # Ensure there is an index on files_id and n, as state may have changed since instantiation of self.
    # Recall that index definitions are cached with ensure_index so this statement won't unneccesarily repeat index creation.
    @chunks.ensure_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]], :unique => true)
    opts     = opts.dup
    filename = opts.delete(:filename)
    opts.merge!(default_grid_io_opts)
    file = GridIO.new(@files, @chunks, filename, 'w', opts)
    file.write(data)
    file.close
    file.files_id
  rescue Mongo::ConnectionFailure => e
    raise e, "Failed to create necessary index and write data."
  end
end

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