(PECL mongo >=0.9.0)
MongoCollection::findOne — Querys this collection, returning a single element
$query = array()
[, array $fields = array()
]] )As opposed to MongoCollection::find(), this method will return only the first result from the result set, and not a MongoCursor that can be iterated over.
query
The fields for which to search. MongoDB's query language is quite extensive. The PHP driver will in almost all cases pass the query straight through to the server, so reading the MongoDB core docs on » find is a good idea.
Please make sure that for all special query operaters (starting with $) you use single quotes so that PHP doesn't try to replace "$exists" with the value of the variable $exists.
fields
Fields of the results to return. The array is in the format array('fieldname' => true, 'fieldname2' => true). The _id field is always returned.
Returns record matching the search or NULL.
Throws MongoConnectionException if it cannot reach the database.
Example #1 MongoCollection::findOne() document by its id.
This example demonstrates how to find a single document in a collection by its id.
<?php
$articles = $mongo->my_db->articles;
$article = $articles->findOne(array('_id' => new MongoId('47cc67093475061e3d9536d2')));
?>
Example #2 MongoCollection::findOne() document by some condition.
This example demonstrates how to find a single document in a collection by some condition and limiting the returned fields.
<?php
$users = $mongo->my_db->users;
$user = $users->findOne(array('username' => 'jwage'), array('password'));
print_r($user);
?>
以上例程的输出类似于：
Array
(
[_id] => MongoId Object
(
)
[password] => test
)
Notice how even though the document does have a username field, we limited the results to only contain the password field.
dominik at dokdok dot com (2010-09-30 11:44:04)
There is also a notation to retrieve all fields, but the specified ones
<?php
$users = $mongo->my_db->users;
$user = $users->findOne(array('username' => 'jwage'), array('password' => 0));
print_r($user);
?>
Will return all fields of the user, but the password field.