Creates a database reference

说明

public array MongoDB::createDBRef ( string $collection , mixed $document_or_id )

This method is a flexible interface for creating database refrences (see MongoDBRef).

参数

collection: The collection to which the database reference will point.
document_or_id: If an array or object is given, its _id field will be used as the reference ID. If a MongoId or scalar is given, it will be used as the reference ID.

返回值

Returns a database reference array.

If an array without an _id field was provided as the document_or_id parameter, NULL will be returned.

范例

Example #1 MongoDB::createDBRef() example

Example demonstrating how to programatically create a DB reference array from a document.


<?php

$articles = $db->articles;

$article = array(
 'title' => 'Test article',
 'description' => 'Test article description'
);

$articles->insert($article);
$ref = $db->createDBRef('articles', $article);

print_r($article);
print_r($ref);
?>

以上例程的输出类似于：

     Array
     (
         [title] => Test article
         [description] => Test article description
         [_id] => MongoId Object
             (
             )

     )
     Array
     (
         [$ref] => articles
         [$id] => MongoId Object
             (
             )

     )

Now the $ref can be stored on another document and retrieved later with MongoDB::getDBRef() or MongoCollection::getDBRef().

Example #2 MongoDB::createDBRef() example

Example demonstrating how to programatically create a DB reference from just an id.


<?php

$id = new MongoId('47cc67093475061e3d9536d2');
$ref = $db->createDBRef('articles', $id);
?>