(mongodb >=1.2.0)
MongoDB\Driver\ReadPreference::bsonSerialize — Returns an object for BSON serialization
Esta función no tiene parámetros.
Returns an object for serializing the ReadPreference as BSON.
Ejemplo #1 MongoDB\Driver\ReadPreference::bsonSerialize() with primary read preference
<?php
$rp = new MongoDB\Driver\ReadPreference(MongoDB\Driver\ReadPreference::RP_PRIMARY);
var_dump($rp->bsonSerialize());
echo "\n", MongoDB\BSON\toJSON(MongoDB\BSON\fromPHP($rp));
?>
El resultado del ejemplo sería algo similar a:
object(stdClass)#2 (1) {
  ["mode"]=>
  string(7) "primary"
}
{ "mode" : "primary" }
Ejemplo #2 MongoDB\Driver\ReadPreference::bsonSerialize() with secondary read preference and tag sets
<?php
$rp = new MongoDB\Driver\ReadPreference(
    MongoDB\Driver\ReadPreference::RP_SECONDARY,
    [
        ['dc' => 'ny'],
        ['dc' => 'sf', 'use' => 'reporting'],
        []
    ]
);
var_dump($rp->bsonSerialize());
echo "\n", MongoDB\BSON\toJSON(MongoDB\BSON\fromPHP($rp));
?>
El resultado del ejemplo sería algo similar a:
object(stdClass)#2 (2) {
  ["mode"]=>
  string(9) "secondary"
  ["tags"]=>
  array(3) {
    [0]=>
    object(stdClass)#1 (1) {
      ["dc"]=>
      string(2) "ny"
    }
    [1]=>
    object(stdClass)#5 (2) {
      ["dc"]=>
      string(2) "sf"
      ["use"]=>
      string(9) "reporting"
    }
    [2]=>
    object(stdClass)#4 (0) {
    }
  }
}
{ "mode" : "secondary", "tags" : [ { "dc" : "ny" }, { "dc" : "sf", "use" : "reporting" }, {  } ] }
Ejemplo #3 MongoDB\Driver\ReadPreference::bsonSerialize() with secondary read preference and max staleness
<?php
$rp = new MongoDB\Driver\ReadPreference(
    MongoDB\Driver\ReadPreference::RP_SECONDARY,
    null,
    ['maxStalenessSeconds' => 120]
);
var_dump($rp->bsonSerialize());
echo "\n", MongoDB\BSON\toJSON(MongoDB\BSON\fromPHP($rp));
?>
El resultado del ejemplo sería algo similar a:
object(stdClass)#2 (2) {
  ["mode"]=>
  string(9) "secondary"
  ["maxStalenessSeconds"]=>
  int(120)
}
{ "mode" : "secondary", "maxStalenessSeconds" : 120 }