/ 
MongoDB-v0.999.998.3-TRIAL
River stage two • 48 direct dependents • 56 total dependents
/ MongoDB::GridFS

NAME

MongoDB::GridFS - A file storage utility

VERSION

version v0.999.998.3

SYNOPSIS

my $grid = $database->get_gridfs;
my $fh = IO::File->new("myfile", "r");
$grid->insert($fh, {"filename" => "mydbfile"});

DESCRIPTION

This class models a GridFS file store in a MongoDB database and provides an API for interacting with it.

Generally, you never construct one of these directly with new. Instead, you call get_gridfs on a MongoDB::Database object.

USAGE

API

There are two interfaces for GridFS: a file-system/collection-like interface (insert, remove, drop, find_one) and a more general interface (get, put, delete). Their functionality is the almost identical (get, put and delete are always safe ops, insert, remove, and find_one are optionally safe), using one over the other is a matter of preference.

Error handling

Unless otherwise explictly documented, all methods throw exceptions if an error occurs. The error types are documented in MongoDB::Error.

To catch and handle errors, the Try::Tiny and Safe::Isa modules are recommended:

use Try::Tiny;
use Safe::Isa; # provides $_isa

try {
    $grid->get( $id )
}
catch {
    if ( $_->$_isa("MongoDB::TimeoutError" ) {
        ...
    }
    else {
        ...
    }
};

To retry failures automatically, consider using Try::Tiny::Retry.

ATTRIBUTES

chunk_size

The number of bytes per chunk. Defaults to 261120 (255kb).

read_preference

A MongoDB::ReadPreference object. It may be initialized with a string corresponding to one of the valid read preference modes or a hash reference that will be coerced into a new MongoDB::ReadPreference object. By default it will be inherited from a MongoDB::Database object.

write_concern

A MongoDB::WriteConcern object. It may be initialized with a hash reference that will be coerced into a new MongoDB::WriteConcern object. By default it will be inherited from a MongoDB::Database object.

prefix

The prefix used for the collections. Defaults to "fs".

METHODS

get

$file = $grid->get($id);

Get a file from GridFS based on its _id. Returns a MongoDB::GridFS::File.

To retrieve a file based on metadata like filename, use the "find_one" method instead.

put

$id = $grid->put($fh, $metadata);
$id = $grid->put($fh, {filename => "pic.jpg"});

Inserts a file into GridFS, adding a MongoDB::OID as the _id field if the field is not already defined. This is a wrapper for MongoDB::GridFS::insert, see that method below for more information.

Returns the _id field.

delete

$grid->delete($id)

Removes the file with the given _id. Will die if the remove is unsuccessful. Does not return anything on success.

find_one

$file = $grid->find_one({"filename" => "foo.txt"});
$file = $grid->find_one($criteria, $fields);

Returns a matching MongoDB::GridFS::File or undef.

remove

$grid->remove({"filename" => "foo.txt"});
$grid->remove({"filename" => "foo.txt"}, $options);

Cleanly removes files from the database. $options is a hash of options for the remove.

A hashref of options may be provided with the following keys:

  • just_one: If true, only one file matching the criteria will be removed.

  • safe: (DEPRECATED) If true, each remove will be checked for success and die on failure. Set the "write_concern" attribute instead.

This method doesn't return anything.

insert

$id = $gridfs->insert($fh);
$id = $gridfs->insert($fh, $metadata);
$id = $gridfs->insert($fh, $metadata, $options);

$id = $gridfs->insert($fh, {"content-type" => "text/html"});

Reads from a file handle into the database. Saves the file with the given metadata. The file handle must be readable.

A hashref of options may be provided with the following keys:

  • safe: (DEPRECATED) Will do safe inserts and check the MD5 hash calculated by the database against an MD5 hash calculated by the local filesystem. If the two hashes do not match, then the chunks already inserted will be removed and the program will die. Set the "write_concern" attribute instead.

Because MongoDB::GridFS::insert takes a file handle, it can be used to insert very long strings into the database (as well as files). $fh must be a FileHandle (not just the native file handle type), so you can insert a string with:

# open the string like a file
open($basic_fh, '<', \$very_long_string);

# turn the file handle into a FileHandle
$fh = FileHandle->new;
$fh->fdopen($basic_fh, 'r');

$gridfs->insert($fh);

drop

$grid->drop;

Removes all files' metadata and contents.

all

@files = $grid->all;

Returns a list of the files in the database as MongoDB::GridFS::File objects.

SEE ALSO

Core documentation on GridFS: http://dochub.mongodb.org/core/gridfs.

AUTHORS

  • David Golden <david@mongodb.com>

  • Mike Friedman <friedo@mongodb.com>

  • Kristina Chodorow <kristina@mongodb.com>

  • Florian Ragwitz <rafl@debian.org>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2015 by MongoDB, Inc..

This is free software, licensed under:

The Apache License, Version 2.0, January 2004