MONGOGRIDFS(3)								 1							    MONGOGRIDFS(3)

The MongoGridFS class

INTRODUCTION

	Utilities for storing and retrieving files from the database.

	GridFS	is  a  storage specification all supported drivers implement. Basically, it defines two collections: files, for file metadata, and
       chunks, for file content. If the file is large, it will automatically be split into smaller chunks and each chunk will be saved as a  docu-
       ment in the chunks collection.

	Each  document in the files collection contains the filename, upload date, and md5 hash. It also contains a unique _id field, which can be
       used to query the chunks collection for the file's content. Each document in the chunks collection contains  a  chunk  of  binary  data,  a
       files_id field that matches its file's _id, and the position of this chunk in the overall file.

	For example, the files document is something like:

       <?php
       array("_id" => 123456789, "filename" => "foo.txt", "chunkSize" => 3, "length" => 12);
       ?>

       <?php
       array("files_id" => 123456789, "n" => 0, "data" => new MongoBinData("abc"));
       array("files_id" => 123456789, "n" => 1, "data" => new MongoBinData("def"));
       array("files_id" => 123456789, "n" => 2, "data" => new MongoBinData("ghi"));
       array("files_id" => 123456789, "n" => 3, "data" => new MongoBinData("jkl"));
       ?>

INTER-LANGUAGE COMPATIBILITY
	You  should  be able to use any files created by MongoGridFS with any other drivers, and vice versa. However, some drivers expect that all
       metadata associated with a file be in a "metadata" field. If you're going to be using other languages, it's a good idea to  wrap  info  you
       might want them to see in a "metadata" field. For example, instead of:

       <?php

       $grid->storeFile("somefile.txt", array("date" => new MongoDate()));

       ?>

	use something like:

       <?php

       $grid->storeFile("somefile.txt", array("metadata" => array("date" => new MongoDate())));

       ?>

THE  MongoGridFS"; FAMILY"
       MongoGridFS  represents the files and chunks collections. MongoGridFS extends MongoCollection, and an instance of MongoGridFS has access to
       all of MongoCollection methods, which act on the files collection:

       <?php

       $grid = $db->getGridFS();
       $grid->update(array("filename" => "foo"), $newObj); // update on the files collection

       ?>

	Another example of manipulating metadata:

       <?php

       // save a file
       $id = $grid->storeFile("game.tgz");
       $game = $grid->findOne();

       // add a downloads counter
       $game->file['downloads'] = 0;
       $grid->save($game->file);

       // increment the counter
       $grid->update(array("_id" => $id), array('$inc' => array("downloads" => 1)));

       ?>

	You can also access the chunks collection from an instance of MongoGridFS:

       <?php

	 $chunks = $grid->chunks; // $chunks is a normal MongoCollection
       $chunks->insert(array("x" => 4));

       ?>

	There are some methods for MongoGridFS with the same name as MongoCollection methods, that behave slightly differently. For example,  Mon-
       goGridFS.remove(3) will remove any objects that match the criteria from the files collection and their content from the chunks collection.

	To store something new in GridFS, there are a couple options. If you have a filename, you can say:

       <?php

       $grid->storeFile($filename, array("whatever" => "metadata", "you" => "want"));

       ?>

	If you have a string of bytes that isn't a file, you can also store that using MongoGridFS.storeBytes(3):

       <?php

       $grid->storeBytes($bytes, array("whatever" => "metadata", "you" => "want"));

       ?>

	Querying a MongoGridFS collection returns a MongoGridFSCursor, which behaves like a normal MongoCursor except that it returns MongoGridFS-
       Files instead of associative arrays.

       MongoGridFSFiles can be written back to disc using MongoGridFSFile.write(3) or retrieved in memory using MongoGridFSFile.getBytes(3). There
       is currently no method that automatically streams chunks, but it would be fairly easy to write by querying the $grid->chunks collection.

       MongoGridFSFile objects contain a field file which contains any file metadata.

CLASS SYNOPSIS

       MongoGridFS

       extends
       MongoCollection

       Fields

       o public MongoCollection$chunks NULL

       o protected string$filesName NULL

       o protected string$chunksName NULL

       Methods

       o public MongoGridFS::__construct (MongoDB  $db, [string  $prefix = "fs"], [mixed  $chunks = "fs"])

       o public bool MongoGridFS::delete (mixed  $id)

       o public array MongoGridFS::drop (void  )

       o public MongoGridFSCursor MongoGridFS::find ([array  $query = array()], [array	$fields = array()])

       o public MongoGridFSFile MongoGridFS::findOne ([mixed  $query = array()], [mixed  $fields = array()])

       o public MongoGridFSFile MongoGridFS::get (mixed  $id)

       o public mixed MongoGridFS::put (string	$filename, [array  $metadata = array()])

       o public bool MongoGridFS::remove ([array  $criteria = array()], [array	$options = array()])

       o public mixed MongoGridFS::storeBytes (string  $bytes, [array  $metadata = array()], [array  $options = array()])

       o public mixed MongoGridFS::storeFile (string  $filename, [array  $metadata = array()], [array  $options = array()])

       o public mixed MongoGridFS::storeUpload (string	$name, [array  $metadata])

SEE ALSO

	      oMongoDB core docs on GridFS

	      oLightCube Solutions blog post on saving user uploads

	      oLightCube Solutions blog post on adding metadata to files

PHP Documentation Group 													    MONGOGRIDFS(3)