After the initial extension set-up, we will continue explaining how to get
  started with the corresponding userland library to write our first project.
 
 
  Installing the PHP Library with Composer
  
   The last thing we still need to install to get started on the application
   itself, is the PHP library.
  
  
   The library needs to be installed with
   » Composer, a package manager
   for PHP. Instructions for installing Composer on various platforms may be
   found on its website.
   
   
    Install the library by running:
    
$ composer require mongodb/mongodb
 
   
   
It will output something akin to:
    
./composer.json has been created
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Installing mongodb/mongodb (1.0.0)
    Downloading: 100%
Writing lock file
Generating autoload files
 
   
   
    Composer will create several files: composer.json,
    composer.lock, and a vendor directory that will
    contain the library and any other dependencies your project might require.
   
   
  
   Using the PHP Library
   
    In addition to managing your dependencies, Composer will also provide you
    with an autoloader (for those dependencies' classes). Ensure that it is
    included at the start of your script or in your application's bootstrap
    code:
    
<?php
// This path should point to Composer's autoloader
require 'vendor/autoload.php';
     
   
   
    With this done, you can now use any of the functionality as described in the
    » library documentation.
   
   
    If you have used MongoDB drivers in other languages, the library's API
    should look familiar. It contains a
    » Client
    class for connecting to MongoDB, a
    » Database
    class for database-level operations (e.g. commands, collection management),
    and a
    » Collection
    class for collection-level operations (e.g.
    » CRUD methods, index management).
   
   
    As an example, this is how you insert a document into the
    beers collection of the demo
    database:
    
<?php
require 'vendor/autoload.php'; // include Composer's autoloader
$client = new MongoDB\Client("mongodb://localhost:27017");
$collection = $client->demo->beers;
$result = $collection->insertOne( [ 'name' => 'Hinterland', 'brewery' => 'BrewDog' ] );
echo "Inserted with Object ID '{$result->getInsertedId()}'";
?>
     
   
   
    Since the inserted document did not contain an _id field, the
    extension will generate an MongoDB\BSON\ObjectId for
    the server to use as the _id. This value is also made available
    to the caller via the result object returned by the insertOne
    method.
   
   
    After insertion, you can query for the data that you have just inserted.
    For that, you use the find method, which returns an iterable
    cursor:
    
<?php
require 'vendor/autoload.php'; // include Composer's autoloader
$client = new MongoDB\Client("mongodb://localhost:27017");
$collection = $client->demo->beers;
$result = $collection->find( [ 'name' => 'Hinterland', 'brewery' => 'BrewDog' ] );
foreach ($result as $entry) {
    echo $entry['_id'], ': ', $entry['name'], "\n";
}
?>
     
   
   
    While it may not be apparent in the examples, BSON documents and arrays are
    unserialized as special classes in the library by default. These classes
    extend ArrayObject for usability and implement the
    extension's MongoDB\BSON\Serializable and
    MongoDB\BSON\Unserializable interfaces to
    ensure that values preserve their type when serialized back into BSON. This
    avoids a caveat in the legacy mongo extension where arrays
    might turn into documents, and vice versa. See the
    Persisting Data specification for more information on
    how values are converted between PHP and BSON.