Provides an array or document to serialize as BSON

# 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|stdClass|MongoDB\BSON\Document|MongoDB\BSON\PackedArray

Called during serialization of the object to BSON. The method must return an array, stdClass, MongoDB\BSON\Document, or MongoDB\BSON\PackedArray.

Root documents (e.g. a MongoDB\BSON\Serializable passed to MongoDB\BSON\Document::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 the constructor) when returning data for a BSON root document. In the absence of an _id property, the extension or server will generate a MongoDB\BSON\ObjectId for insert or upsert operations, respectively.

### Parameters

This function has no parameters.

### Return Values

An array, stdClass, MongoDB\BSON\Document, or MongoDB\BSON\PackedArray to be serialized as a BSON array or document.

### Changelog

Version | Description
--- | ---
PECL mongodb 2.0.0 | Return types previously declared as tentative are now enforced.
PECL mongodb 1.17.0 | The return type was changed from array|object. Instead of object, the return type now specifies stdClass. Classes that implement this interface must be changed to no longer declare an object return type. As the return type is tentative, a deprecation warning is emitted on PHP 8.1 and newer. In addition to the changes above, the extension now also supports returning instances of MongoDB\BSON\Document and MongoDB\BSON\PackedArray. Please note that any MongoDB\BSON\PackedArray instances returned are silently converted to objects when stored as root documents. They are stored as arrays when used as an embedded field value.

### 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(): array
{
return ['_id' => $this->id, 'foo' => 'bar'];
}
}
echo MongoDB\BSON\Document::fromPHP(new MyDocument)->toRelaxedExtendedJSON(), "\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(): array
{
return [1, 2, 3];
}
}
echo MongoDB\BSON\Document::fromPHP(new MyArray)->toRelaxedExtendedJSON(), "\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(): array
{
return ['foo' => 'bar'];
}
}
$value = ['document' => new MyDocument];
echo MongoDB\BSON\Document::fromPHP($value)->toRelaxedExtendedJSON(), "\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(): array
{
return [1, 2, 3];
}
}
$value = ['array' => new MyArray];
echo MongoDB\BSON\Document::fromPHP($value)->toRelaxedExtendedJSON(), "\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

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