Just to be careful with the strict comparison. Object inequalities holds.
<?php
$m1 = new MongoId('51b14c2de8e185801f000006');
$m2 = new MongoId('51b14c2de8e185801f000006');
var_dump($m1 === $m2); //gives you boolean false
var_dump($m1 == $m2); //gives you boolean true
$m3 = new MongoId('51b14c2de8e185801f000006');
$m4 = new MongoId('51b14c2de8e185801f000007');
var_dump($m3 === $m4); //gives you boolean false
var_dump($m3 == $m4); //gives you boolean false
?>
MongoId 类
(PECL mongo >=0.8.0)
简介
为数据库对象创建的唯一标识符。 如果插入数据库的对象不具有 _id 字段，将会为 _id 字段添加一个 MongoId 实例作为值。 如果数据具有自然的唯一字段（比如说，用户名或 timestamp），用来作为 _id 字段也不错，它不会被 一个 MongoId 替换。
MongoId 类实例满足了关系数据库中自增列的角色： 如果数据不具有天然的唯一键，则提供一个。 自增列在分布式数据库中不会工作得很好，因为它无法快速找到下一个数字。 这个类能够满足在分布式下快速产生唯一值的条件。
每个 MongoId 具有 12 个字节（使它的字符串形式是 24 个十六进制字符）。 前四个字节是一个时间戳（timestamp），后三个是客户端主机名的 hash 摘要，然后两个是运行脚本的进程 ID， 最后三位是一个自增值。
MongoId 是可以序列化/反序列化的。 它们序列化后的格式和它们的字符串格式比较像：
C:7:"MongoId":24:{4af9f23d8ead0e1d32000000}
类摘要
MongoId
{
public
string
id
=
NULL
;/* 方法 */
}Fields
- id
- 这个字段包含了该对象的字符串表达形式。
参见
关于 » ids 的 MongoDB 核心文档。
Table of Contents
- MongoId::__construct — 创建一个新的id
- MongoId::getHostname — 获取这台机器上 id 所使用的 hostname
- MongoId::getInc — 返回用于创建 id 所增加的值
- MongoId::getPID — 获取进程 ID
- MongoId::getTimestamp — 获取新纪元时间到 id 创建时的秒数。
- MongoId::isValid — Check if a value is a valid ObjectId
- MongoId::__set_state — 创建一个假的 MongoId
- MongoId::__toString — 返回该 id 十六进制的表示形式
add a note
User Contributed Notes 7 notes
Lionel ¶
11 years ago
rmarscher ¶
12 years ago
You can also cast the id to a string rather than access the $id property to get a string representation of the MongoId.
<?php
$stringId = (string) $mongoId;
?>
georgedot dont spam me gmail caom ¶
11 years ago
Due to Recent changes.
* [PHP-554] - MongoId should not get constructed when passing in an invalid ID.
Constructor will throw an exception when passing invalid ID.
<?php
$_id = new MongoId(); //Generates new ID
$_id = new MongoId(null); //Generates new ID
$_id = new MongoId("invalid id"); //throws MongoException
?>
<?php
//Revert to old behaviour
$_id = "invalid id";
try {
$_id = new MongoId($_id);
} catch (MongoException $ex) {
$_id = new MongoId();
}
?>
<?php
//Nifty hack
class SafeMongoId extends MongoId {
public function __construct($id=null) {
try {
parent::__construct($id);
} catch (MongoException $ex) {
parent::__construct(null);
}
}
}
?>
Ryan S ¶
11 years ago
it is important to note that
<?php
array("_id" => new MongoId("50cf7d2841d41f4f35000000"))
// ≠
array("_id" => array("$id" => "50cf7d2841d41f4f35000000"))
?>
This issue can arrise when using json_encode() and json_decode(). If not paying close enough attention one can assume due to the encoded value of the object that it is just this simple:
<?php
$item = $db->myCollection->findOne();
print json_encode($item);
// {"_id": {"$id": "50cf7d2841d41f4f35000000"}}
$item = $db->myCollection->findOne(json_encode($item));
// $item is empty aka not found
?>
Simple solution to handle these situations:
<?php
class MongoId2 extends MongoId {
public function __construct($id = null) {
if(is_array($id)) {
$id = (object) $id;
}
if(is_object($id) && isset($id->{'$id'})) {
$id = $id->{'$id'};
}
return parent::__construct($id);
}
}
?>
lensvil dot co at gmail dot com ¶
8 years ago
Get ObjectId MongoDB via PHP
var_dump($object);
object(MongoDB\Model\BSONDocument)#36 (1) {
["storage":"ArrayObject":private]=>
array(8) {
["_id"]=>
object(MongoDB\BSON\ObjectID)#33 (1) {
["oid"]=>
string(24) "573e69e78fccd968aa066611"
}
["dummy"]=>
string(5) "mongo"
}
}
Failure
var_dump($object->_id->oid);
>>> null
var_dump($object->_id->{'oid'});
>>> null
var_dump($object->_id->{'$oid'});
>>> null
Success
$bson = \MongoDB\BSON\fromPHP($object);
$json = \MongoDB\BSON\toJSON($bson);
$result = json_decode($json, true);
var_dump($result['_id']['$oid']);
>>> string(24) "573e69e78fccd968aa066611"
exit;
sararschreiber at gmail dot com ¶
14 years ago
this is useful for querying for an object by id, given the id's hex:
<?php
$userid = '4cb4ab6d7addf98506010000';
$theObjId = new MongoId($userid);
$connection = new Mongo();
$db = $connection->thedb->users;
// this will return our matching entry.
$item = $db->findOne(array("_id" => $theObjId));
$connection->close();
?>
alex dot turpin at gmail dot com ¶
13 years ago
If you need to get the actual ID string, and you try the usual way, PHP will whine because it starts with a dollar sign and it thinks it's a variable. Instead, use this notation:
<?php
$mongoid->{'$id'} //Get the $id property of a MongoId object
?>
