# MongoDB\BSON\Serializable::bsonSerialize

(mongodb >=1.0.0)

MongoDB\BSON\Serializable::bsonSerialize — Provides an array or document to serialize as BSON

### Description

abstract public MongoDB\BSON\Serializable::bsonSerialize ( ) : array|object

Called during serialization of the object to BSON. The method must return an array or stdClass.

Root documents (e.g. a MongoDB\BSON\Serializable passed to MongoDB\BSON\fromPHP()) will always be serialized as a BSON document. For field values, associative arrays and stdClass instances will be serialized as a BSON document and sequential arrays (i.e. sequential, numeric indexes starting at `0`) will be serialized as a BSON array.

Users are encouraged to include an _id property (e.g. a MongoDB\BSON\ObjectId initialized in your constructor) when returning data for a BSON root document; otherwise, the driver or database will need to generate a MongoDB\BSON\ObjectId when inserting or upserting the document, respectively.

### Parameters

This function has no parameters.

### Return Values

An array or stdClass to be serialized as a BSON array or document.

### Examples

Example #1 MongoDB\BSON\Serializable::bsonSerialize() returning an associative array for root document

`<?php
class MyDocument implements MongoDB\BSON\Serializable
{
private $id;
function __construct()
{
$this->id = new MongoDB\BSON\ObjectId;
}
function bsonSerialize()
{
return ['_id' => $this->id, 'foo' => 'bar'];
}
}
$bson = MongoDB\BSON\fromPHP(new MyDocument);
echo MongoDB\BSON\toJSON($bson), "\n";
?>`

The above example will output something similar to:

    { "_id" : { "$oid" : "56cccdcada14d8755a58c591" }, "foo" : "bar" }

Example #2 MongoDB\BSON\Serializable::bsonSerialize() returning a sequential array for root document

`<?php
class MyArray implements MongoDB\BSON\Serializable
{
function bsonSerialize()
{
return [1, 2, 3];
}
}
$bson = MongoDB\BSON\fromPHP(new MyArray);
echo MongoDB\BSON\toJSON($bson), "\n";
?>`

The above example will output:

    { "0" : 1, "1" : 2, "2" : 3 }

Example #3 MongoDB\BSON\Serializable::bsonSerialize() returning an associative array for document field

`<?php
class MyDocument implements MongoDB\BSON\Serializable
{
function bsonSerialize()
{
return ['foo' => 'bar'];
}
}
$value = ['document' => new MyDocument];
$bson = MongoDB\BSON\fromPHP($value);
echo MongoDB\BSON\toJSON($bson), "\n";
?>`

The above example will output:

    { "document" : { "foo" : "bar" } }

Example #4 MongoDB\BSON\Serializable::bsonSerialize() returning a sequential array for document field

`<?php
class MyArray implements MongoDB\BSON\Serializable
{
function bsonSerialize()
{
return [1, 2, 3];
}
}
$value = ['array' => new MyArray];
$bson = MongoDB\BSON\fromPHP($value);
echo MongoDB\BSON\toJSON($bson), "\n";
?>`

The above example will output:

    { "array" : [ 1, 2, 3 ] }

### See Also

- MongoDB\BSON\Unserializable::bsonUnserialize() - Constructs the object from a BSON array or document
- MongoDB\BSON\Persistable
- Persisting Data