# Using the PHP Library for MongoDB (PHPLIB)

After the initial driver set-up, we will continue explaining how to get started with the MongoDB driver and 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 driver 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 type classes in the library by default. These classes ensure that values preserve their type when being serialized back into BSON, which avoids a caveat in the old driver where arrays might turn into documents, and vice versa. Additionally, these type classes extend `ArrayObject` for enhanced usability. You can find more information on how serialization and deserialization between PHP variables and BSON is handled by the driver and library by reading the mongodb.persistence specification.